Science.gov

Sample records for active hydrothermal processes

  1. Hydrothermal Processes

    NASA Astrophysics Data System (ADS)

    German, C. R.; von Damm, K. L.

    2003-12-01

    species escape from the seafloor in high abundance. When they do, the buoyancy of the high-temperature fluids carries them hundreds of meters up into the overlying water column as they mix and eventually form nonbuoyant plumes containing a wide variety of both dissolved chemicals and freshly precipitated mineral phases. The processes active within these dispersing hydrothermal plumes play a major role in determining the net impact of hydrothermal circulation upon the oceans and marine geochemistry.

  2. Hydrothermal Processing

    SciTech Connect

    Elliott, Douglas C.

    2011-03-11

    This chapter is a contribution to a book on Thermochemical Conversion of Biomass being edited by Prof. Robert Brown of Iowa State University. It describes both hydrothermal liquefaction and hydrothermal gasification of biomass to fuels.

  3. Enceladus: Starting Hydrothermal Activity

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    We describe a process for starting the hydrothermal activity in Enceladus' South Polar Region. The process takes advantage of fissures that reach the water table, about 1 kilometer below the surface. Filling these fissures with fresh ocean water initiates a flow of water up from an ocean that can be self-sustaining. In this hypothesis the heat to sustain the thermal anomalies and the plumes comes from a slightly warm ocean at depth. The heat is brought to the surface by water that circulates up, through the crust and then returns to the ocean.

  4. Hydrothermal activity in Tertiary Icelandic crust: Implication for cooling processes along slow-spreading mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pałgan, D.; Devey, C. W.; Yeo, I. A.

    2015-12-01

    Known hydrothermal activity along the Mid-Atlantic Ridge is mostly high-temperature venting, controlled by volcano-tectonic processes confined to ridge axes and neotectonic zones ~15km wide on each side of the axis (e.g. TAG or Snake Pit). However, extensive exploration and discoveries of new hydrothermal fields in off-axis regions (e.g. Lost City, MAR) show that hydrothermalism may, in some areas, be dominated by off-axis venting. Little is known about nature of such systems, including whether low-temperature "diffuse" venting dominates rather than high-temperature black-smokers. This is particularly interesting since such systems may transport up to 90% of the hydrothermal heat to the oceans. In this study we use Icelandic hot springs as onshore analogues for off-shore hydrothermal activity along the MAR to better understand volcano-tectonic controls on their occurrence, along with processes supporting fluid circulation. Iceland is a unique laboratory to study how new oceanic crust cools and suggests that old crust may not be as inactive as previously thought. Our results show that Tertiary (>3.3 Myr) crust of Iceland (Westfjords) has widespread low-temperature hydrothermal activity. Lack of tectonism (indicated by lack of seismicity), along with field research suggest that faults in Westfjords are no longer active and that once sealed, can no longer support hydrothermal circulation, i.e. none of the hot springs in the area occur along faults. Instead, dyke margins provide open and permeable fluid migration pathways. Furthermore, we suggest that the Reykjanes Ridge (south of Iceland) may be similar to Westfjords with hydrothermalism dominated by off-axis venting. Using bathymetric data we infer dyke positions and suggest potential sites for future exploration located away from neotectonic zone. We also emphasise the importance of biological observations in seeking for low-temperature hydrothermal activity, since chemical or optical methods are not sufficient.

  5. Hydrothermal processes at seafloor spreading centers,

    SciTech Connect

    Rona, P.A.; Bostrom, K.; Laubier, L.; Smith, K.L.

    1983-01-01

    This book examines research on the description and interpretation of hydrothermal and associated phenomena at seafloor spreading centers. An interdisciplinary overview of the subject is presented, including geological, geophysical, geochemical, and biological discoveries. The implications of the discoveries for understanding the earth's heat transfer, geochemical mass balances and cycles, mineralization, and biological adaptation are discussed. Topics considered include geologic setting (e.g., the four dimensions of the spreading axis, geological processes of the mid-ocean ridge), hydrothermal convection (e.g., oxygen and hydrogen isotope studies, the basic physics of water penetration into hot rock), Iceland and oceanic ridges (e.g., chemical evidence from Icelandic geothermal systems, the physical environment of hydrothermal systems), mass balances and cycles (e.g., reduced gases and bacteria in hydrothermal fluids, the effects of hydrothermal activity on sedimentary organic matter), ferromanganese deposits, hydrothermal mineralization, and the biology of hydrothermal vents.

  6. Hydrothermal processes above the Yellowstone magma chamber: Large hydrothermal systems and large hydrothermal explosions

    USGS Publications Warehouse

    Morgan, L.A.; Shanks, W.C. Pat; Pierce, K.L.

    2009-01-01

    Hydrothermal explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments from source craters that range from a few meters up to more than 2 km in diameter; associated breccia can be emplaced as much as 3 to 4 km from the largest craters. Hydrothermal explosions occur where shallow interconnected reservoirs of steam- and liquid-saturated fluids with temperatures at or near the boiling curve underlie thermal fields. Sudden reduction in confi ning pressure causes fluids to fl ash to steam, resulting in signifi cant expansion, rock fragmentation, and debris ejection. In Yellowstone, hydrothermal explosions are a potentially signifi cant hazard for visitors and facilities and can damage or even destroy thermal features. The breccia deposits and associated craters formed from hydrothermal explosions are mapped as mostly Holocene (the Mary Bay deposit is older) units throughout Yellowstone National Park (YNP) and are spatially related to within the 0.64-Ma Yellowstone caldera and along the active Norris-Mammoth tectonic corridor. In Yellowstone, at least 20 large (>100 m in diameter) hydrothermal explosion craters have been identifi ed; the scale of the individual associated events dwarfs similar features in geothermal areas elsewhere in the world. Large hydrothermal explosions in Yellowstone have occurred over the past 16 ka averaging ??1 every 700 yr; similar events are likely in the future. Our studies of large hydrothermal explosion events indicate: (1) none are directly associated with eruptive volcanic or shallow intrusive events; (2) several historical explosions have been triggered by seismic events; (3) lithic clasts and comingled matrix material that form hydrothermal explosion deposits are extensively altered, indicating that explosions occur in areas subjected to intense hydrothermal processes; (4) many lithic clasts contained in explosion breccia deposits preserve evidence of repeated fracturing

  7. Hydrothermal activity and subsurface soil complexity: implication for outgassing processes at Solfatara crater, Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Montanaro, Cristian; Mayer, Klaus; Scheu, Bettina; Isaia, Roberto; Mangiacapra, Annarita; Gresse, Marceau; Vandemeulebrouck, Jean; Moretti, Roberto; Dingwell, Donald B.

    2016-04-01

    The Solfatara area and its fumaroles are the main surface phenomena of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing which in turn leads to a strong alteration of the volcanic products. Moreover the maar-nature of the crater, and its filling by more recent volcanic deposits, resulted in a complex fractured and multilayered cap to the rising gases. As a consequence the hydrothermal alteration differently affects the rocks within the crater, including pyroclastic fallout ash beds, pyroclastic density current deposits, breccias and lavas. The induced changes in both original microstructure and physical and mechanical properties of the rocks control the outgassing behavior. Here, we report results from a measurement survey conducted in July 2015, and aimed to characterize the in-situ physical (temperature, humidity) and mechanical (permeability, strength, stiffness) properties. The survey also included a mapping of the surficial hydrothermal features and their distributions. Chemical analyses and laboratory measurements (porosity, granulometry) of selected samples were additionally performed. Results show that the crater floor area comprises very different kinds of soils, from fine grained, thin laminated deposits around the two bubbling Fangaia mud pools, to crusted hummock formations along the SE and NE border of the crater. Dry and solid alunite-rich deposits are present in the western and southern part. Furthermore we observed evidences of a beginning of crust formation within the central part of the crater. A large range of surface temperatures, from boiling point to ambient temperature, were measured throughout the surveyed area. Outgassing occurs mainly along the crack system, which has also generated the crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and highly porous sulfur-hardened levels, whereas

  8. Stable isotopes in seafloor hydrothermal systems: Vent fluids, hydrothermal deposits, hydrothermal alteration, and microbial processes

    USGS Publications Warehouse

    Shanks, Wayne C.

    2001-01-01

    The recognition of abundant and widespread hydrothermal activity and associated unique life-forms on the ocean floor is one of the great scientific discoveries of the latter half of the twentieth century. Studies of seafloor hydrothermal processes have led to revolutions in understanding fluid convection and the cooling of the ocean crust, the chemical and isotopic mass balance of the oceans, the origin of stratiform and statabound massive-sulfide ore-deposits, the origin of greenstones and serpentinites, and the potential importance of the subseafloor biosphere. Stable isotope geochemistry has been a critical and definitive tool from the very beginning of the modern era of seafloor exploration.

  9. Arctic Ocean: hydrothermal activity on Gakkel Ridge.

    PubMed

    Jean-Baptiste, Philippe; Fourré, Elise

    2004-03-04

    In the hydrothermal circulation at mid-ocean ridges, sea water penetrates the fractured crust, becomes heated by its proximity to the hot magma, and returns to the sea floor as hot fluids enriched in various chemical elements. In contradiction to earlier results that predict diminishing hydrothermal activity with decreasing spreading rate, a survey of the ultra-slowly spreading Gakkel Ridge (Arctic Ocean) by Edmonds et al. and Michael et al. suggests that, instead of being rare, the hydrothermal activity is abundant--exceeding by at least a factor of two to three what would be expected by extrapolation from observation on faster spreading ridges. Here we use helium-3 (3He), a hydrothermal tracer, to show that this abundance of venting sites does not translate, as would be expected, into an anomalous hydrothermal 3He output from the ridge. Because of the wide implications of the submarine hydrothermal processes for mantle heat and mass fluxes to the ocean, these conflicting results call for clarification of the link between hydrothermal activity and crustal production at mid-ocean ridges.

  10. Microbial bio-mineralization processes in hydrothermal travertine: the case study of two active travertine systems (Tuscany, Italy).

    NASA Astrophysics Data System (ADS)

    Barilaro, Federica; Bontognali, Tomaso R. R.; Mc Kenzie, Judith A.; Vasconcelos, Crisogono

    2015-04-01

    Modern hydrothermal travertine deposits, occurring today at Bagni San Filippo (Radicofani Basin) and at Bagni di Saturnia (Albegna Valley) in Tuscany, Central Italy, have been investigated with the main purpose to improve the understanding of the processes that control calcium carbonate precipitation in hydrothermal-spring settings. Present-day thermal activity at Bagni di Saturnia is characterized by a 37.5°C thermal spring with a rate of about 800 l/s, with a pH of ca. 6.4. Thermal water discharges at Bagni San Filippo reach a rate of 20 litres per second at a maximum temperature of 50°C and a pH of ca. 7. The springs expel water enriched in H2S-CO2-SO42- and HCO3- and divalent cations (Ca and Mg). In the studied areas, travertine precipitation occurs in association with living microbial mats and biofilms, composed of a heterogeneous community of green algae, filamentous cyanobacteria and other types of prokaryotes, anoxygenic photosynthetic bacteria and heterotrophic heat-tolerant bacteria, with a variable amount of extracellular polymeric substances (EPS). Nine categories of fabric types, dominantly calcite and aragonite in composition, showing a wide range of macro- and micro-porosity, have been identified. High magnification analysis of dendritic and laminated boundstone, crystalline crust cementstone, raft boundstone, coated bubble boundstone, micrite mudstone and coated reed boundstone fabric types, suggests that precipitation occurs in association with organic matter. Diatoms, cyanobacteria filaments and other bacteria are then associated with the EPS and often appear totally or partially entombed (passively or actively) in it. Organic extracellular polymeric substances (EPS) and often the external surface of cyanobacterial sheaths are the location where the calcite minerals nucleate and grow. Precipitation begins with organomineral nano-globules consisting of nanometre-size, from sub-spherical to globular-like, raised structures (5 to 80 nm diameter

  11. Ongoing hydrothermal activities within Enceladus.

    PubMed

    Hsu, Hsiang-Wen; Postberg, Frank; Sekine, Yasuhito; Shibuya, Takazo; Kempf, Sascha; Horányi, Mihály; Juhász, Antal; Altobelli, Nicolas; Suzuki, Katsuhiko; Masaki, Yuka; Kuwatani, Tatsu; Tachibana, Shogo; Sirono, Sin-iti; Moragas-Klostermeyer, Georg; Srama, Ralf

    2015-03-12

    Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneath an ice crust 30 to 40 kilometres thick. These findings imply rock-water interactions in regions surrounding the core of Enceladus. The resulting chemical 'footprints' are expected to be preserved in the liquid and subsequently transported upwards to the near-surface plume sources, where they eventually would be ejected and could be measured by a spacecraft. Here we report an analysis of silicon-rich, nanometre-sized dust particles (so-called stream particles) that stand out from the water-ice-dominated objects characteristic of Saturn. We interpret these grains as nanometre-sized SiO2 (silica) particles, initially embedded in icy grains emitted from Enceladus' subsurface waters and released by sputter erosion in Saturn's E ring. The composition and the limited size range (2 to 8 nanometres in radius) of stream particles indicate ongoing high-temperature (>90 °C) hydrothermal reactions associated with global-scale geothermal activity that quickly transports hydrothermal products from the ocean floor at a depth of at least 40 kilometres up to the plume of Enceladus.

  12. Investigation of hydrothermal activity at Campi Flegrei caldera using 3D numerical simulations: Extension to high temperature processes

    NASA Astrophysics Data System (ADS)

    Afanasyev, Andrey; Costa, Antonio; Chiodini, Giovanni

    2015-06-01

    Hydrothermal activity at Campi Flegrei caldera is simulated by using the multiphase code MUFITS. We first provide a brief description of the simulator covering the mathematical formulation and its applicability at elevated supercritical temperatures. Then we apply, for the first time, the code to hydrothermal systems investigating the Campi Flegrei caldera case. We consider both shallow subcritical regions and deep supercritical regions of the hydrothermal system. We impose sophisticated boundary conditions at the surface to provide a better description of the reservoir interactions with the atmosphere and the sea. Finally we carry out a parametric study and compare the simulation results with gas temperature and composition, gas and heat fluxes, and temperature measurements in the wells of that area. Results of the parametric study show that flow rate, composition, and temperature of the hot gas mixture injected at depth, and the initial geothermal gradient strongly control parameters monitored at Solfatara. The results suggest that the best guesses conditions for the gas mixture injected at 5 km depth correspond to a temperature of ~ 700 °C, a fluid mass flow rate of about 50-100 kg/s, and an initial geothermal gradient of ~ 120 °C/km.

  13. Synthesis of large surface area nano-sized BiVO{sub 4} by an EDTA-modified hydrothermal process and its enhanced visible photocatalytic activity

    SciTech Connect

    Sun Wanting; Xie Mingzheng; Jing Liqiang; Luan Yunbo; Fu Honggang

    2011-11-15

    In this work, monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been successfully synthesized, using Bi(NO{sub 3}){sub 3} and NH{sub 4}VO{sub 3} as raw materials, through a hydrothermal process in the presence of ethylene diamine tetraacetic acid (EDTA). It is demonstrated that the nanoparticle size of as-prepared BiVO{sub 4} becomes small by decreasing hydrothermal temperature, shortening hydrothermal reaction time and increasing EDTA amount used. The resulting BiVO{sub 4} nanoparticle with large surface area exhibits a good photocatalytic performance for degrading phenol solution as a model organic pollutant under visible illumination. The key of this method is the chelating role of EDTA group in the synthetic process that it can greatly control the concentration of Bi{sup 3+}, leading to the growth inhibition of BiVO{sub 4} crystallite. The work provides a route for the synthesis of Bi-containing nano-sized composite oxides with large surface area. - Graphical abstract: High visible active nano-sized BiVO{sub 4} photocatalyst with large surface area is successfully synthesized, which is attributed to the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. Highlights: > Monoclinic scheelite-type BiVO{sub 4} nanoparticle with large surface area has been synthesized by a hydrothermal process. > Key of this method is the chelating role of EDTA group inhibiting the growth of BiVO{sub 4} crystallites. > Resulting nano-sized BiVO{sub 4} exhibits a good photocatalytic activity for degrading phenol under visible illumination.

  14. Effects of process parameters on hydrothermal carbonization

    NASA Astrophysics Data System (ADS)

    Uddin, Md. Helal

    In recent years there has been increased research activity in renewable energy, especially upgrading widely available lignicellulosic biomass, in a bid to counter the increasing environmental concerns related with the use of fossil fuels. Hydrothermal carbonization (HTC), also known as wet torrefaction or hot water pretreatment, is a process for pretreatment of diverse lignocellulosic biomass feedstocks, where biomass is treated under subcritical water conditions in short contact time to produce high-value products. The products of this process are: a solid mass characterized as biochar/biocoal/biocarbon, which is homogeneous, energy dense, and hydrophobic; a liquid stream composed of five and six carbon sugars, various organic acids, and 5-HMF; and a gaseous stream, mainly CO2. A number of process parameters are considered important for the extensive application of the HTC process. Primarily, reaction temperature determines the characteristics of the products. In the solid product, the oxygen carbon ratio decreases with increasing reaction temperature and as a result, HTC biochar has the similar characteristics to low rank coal. However, liquid and gaseous stream compositions are largely correlated with the residence time. Biomass particle size can also limit the reaction kinetics due to the mass transfer effect. Recycling of process water can help to minimize the utility consumption and reduce the waste treatment cost as a result of less environmental impact. Loblolly pine was treated in hot compressed water at 200 °C, 230 °C, and 260 °C with 5:1 water:biomass mass ratio to investigate the effects of process parameters on HTC. The solid product were characterized by their mass yields, higher heating values (HHV), and equilibrium moisture content (EMC), while the liquid were characterized by their total organic carbon content and pH value.

  15. Hydrothermal alkali metal recovery process

    DOEpatents

    Wolfs, Denise Y.; Clavenna, Le Roy R.; Eakman, James M.; Kalina, Theodore

    1980-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles by treating them with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of an added base to establish a pH during the treatment step that is higher than would otherwise be possible without the addition of the base. During the treating process the relatively high pH facilitates the conversion of water-insoluble alkali metal compounds in the alkali metal residues into water-soluble alkali metal constituents. The resultant aqueous solution containing water-soluble alkali metal constituents is then separated from the residue solids, which consist of the treated particles and any insoluble materials formed during the treatment step, and recycled to the gasification process where the alkali metal constituents serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. Preferably, the base that is added during the treatment step is an alkali metal hydroxide obtained by water washing the residue solids produced during the treatment step.

  16. Hydrothermal processes at seafloor spreading centers,

    SciTech Connect

    Sleep, N.H.

    1983-01-01

    This chapter discusses the initial entry of hydrothermal seawater into deep levels of the oceanic crust, the effectiveness of hydrothermal circulation in cooling the crust, the geometry of hydrothermal circulation, the relationship between the hydrothermal circulation and the magma chamber, the reaction of the oceanic crust with the seawater, and the identification of the hydrothermal fluid which alters a rock sample. Topics considered include the crack front, observation relevant to the crack front, the limitations of the crack front hypothesis, the observed pattern of hydrothermal alteration, the nature of the hydrothermal fluid, the physics of large scale convection, and convection through crack zones. Knowledge of hydrothermal circulation at the ridge axis is based on sampling of the hydrothermal fluid, indirect geophysical measurements of the oceanic crust, and studies of rocks which are believed to have undergone hydrothermal alteration at the ridge axis. Includes 2 drawings.

  17. Genifuel Hydrothermal Processing Bench Scale Technology ...

    EPA Pesticide Factsheets

    Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of the Genifuel hydrothermal process technology for handling municipal wastewater sludge. HTL tests were conducted at 300-350◦C and 2900 psig on three different feeds: primary sludge (11.9 wt% solids), secondary sludge (9.7 wt% solids), and post-digester sludge (also referred to as digested solids) (16.0 wt% solids). Corresponding CHG tests were conducted at 350◦C and 2900 psig on the HTL aqueous phase product using a ruthenium based catalyst. A comprehensive analysis of all feed and effluent phases was also performed. Total mass and carbon balances closed to within ± 15% in all but one case. Biocrude yields from HTL tests were 37%, 25%, and 34% for primary sludge, secondary sludge, and digested solids feeds, respectively. The biocrude yields accounted for 59%, 39%, and 49% of the carbon in the feed for primary sludge, secondary sludge, and digested solids feeds, respectively. It should be noted that HTL test results for secondary sludge may have been affected by equipment problems. Biocrude composition and quality were comparable to that seen with biocrudes generated from algae feeds. CHG product gas consisted primarily of methane, with methane yields (relative to CHG input) on a carbon basis of 47%, 61%, and 64% for aqueous feeds that were the product of HTL tests with primary sludge, secondary sludge, and

  18. Hydrothermal processes at Mount Rainier, Washington

    SciTech Connect

    Frank, D.G.

    1985-01-01

    Field studies and thermal-infrared mapping at Mount Rainier indicate areas of active hydrothermal alteration where excess surface heat flux is about 9 megawatts. Three representative settings include: (1) An extensive area (greater than 12,000 m/sup 2/) of heated ground and slightly acidic boiling-point fumaroles at 76-82/sup 0/C at East and West Craters on the volcano's summit; (2) A small area (less than 500 m/sup 2/) of heated ground and sub-boiling-point fumaroles at 55-60/sup 0/C on the upper flank at Disappointment Cleaver, and other probably similar areas at Willis Wall, Sunset Amphitheater, and the South Tahoma and Kautz headwalls; (3) Sulfate and carbon dioxide enriched thermal springs at 9-24/sup 0/C on the lower flank of the volcano in valley walls beside the Winthrop and Paradise Glaciers. In addition, chloride- and carbon dioxide-enriched thermal springs issue from thin sediments that overlie Tertiary rocks at, or somewhat beyond, the base of the volcanic edifice in valley bottoms of the Nisqually and Ohanapecosh Rivers where maximum spring temperatures are 19-25/sup 0/C, respectively, and where extensive travertine deposits have developed. The heat flow, distribution of thermal activity, and nature of alteration products indicate that a narrow, central hydrothermal system exists within Mount Rainier forming steam-heated snowmelt at the summit craters and localized leakage of steam-heated fluids within 2 kilometers of the summit. The lateral extent of the hydrothermal system is limited in that only sparse, neutral sulfate-enriched thermal water issues from the lower flank of the cone. Simulations of geochemical mass transfer suggest that the thermal springs may be derived from an acid sulfate-chloride parent fluid which has been neutralized by reaction with andesite and highly diluted with shallow ground water.

  19. Anaerobic digestion of post-hydrothermal liquefaction wastewater for improved energy efficiency of hydrothermal bioenergy processes.

    PubMed

    Zhou, Yan; Schideman, Lance; Zheng, Mingxia; Martin-Ryals, Ana; Li, Peng; Tommaso, Giovana; Zhang, Yuanhui

    2015-01-01

    Hydrothermal liquefaction (HTL) is a promising process for converting wet biomass and organic wastes into bio-crude oil. It also produces an aqueous product referred to as post-hydrothermal liquefaction wastewater (PHWW) containing up to 40% of the original feedstock carbon, which reduces the overall energy efficiency of the HTL process. This study investigated the feasibility of using anaerobic digestion (AD) to treat PHWW, with the aid of activated carbon. Results showed that successful AD occurred at relatively low concentrations of PHWW (≤ 6.7%), producing a biogas yield of 0.5 ml/mg CODremoved, and ∼53% energy recovery efficiency. Higher concentrations of PHWW (≥13.3%) had an inhibitory effect on the AD process, as indicated by delayed, slower, or no biogas production. Activated carbon was shown to effectively mitigate this inhibitory effect by enhancing biogas production and allowing digestion to proceed at higher PHWW concentrations (up to 33.3%), likely due to sequestering toxic organic compounds. The addition of activated carbon also increased the net energy recovery efficiency of AD with a relatively high concentration of PHWW (33.3%), taking into account the energy for producing activated carbon. These results suggest that AD is a feasible approach to treat PHWW, and to improve the energy efficiency of the HTL processes.

  20. Hydrothermal Activity in the Northern Guaymas Basin

    NASA Astrophysics Data System (ADS)

    Berndt, C.; Hensen, C.; Mortera-Gutierrez, C. A.; Sarkar, S.; Geilert, S.; Schmidt, M.; Liebetrau, V.; Kipfer, R.; Scholz, F.; Doll, M.; Muff, S.; Karstens, J.; Böttner, C.; Chi, W. C.; Moser, M.; Behrendt, R.; Fiskal, A.; Evans, T.; Planke, S.; Lizarralde, D.; Lever, M. A.

    2015-12-01

    Rift-related magmatism in the Guaymas Basin, Gulf of California induces hydrothermal activity within the basin sediments. Mobilized fluids migrate to the seafloor where they are emitted into the water column changing ocean chemistry and fuelling chemosynthetic ecosystems. New seismic and geochemical data from the northern rift arm of the Guaymas Basin document the variety of fluid expulsion phenomena from large-scale subsurface sediment mobilization related to contact metamorphosis to focused small-scale structures. The geochemical composition of emitted fluids depends largely on the age of the fluid escape structures with respect to the underlying intrusions. Whereas, old structures are dominated by methane emission, young vent sites are characterized by hot fluids that carry a wide range of minerals in solution. The overall high geothermal gradient within the basin (mainly between 160 and 260 °C/km) leads to a thin gas hydrate stability zone. Thus, deep hydrothermal fluid advection affects the gas hydrate system and makes it more dynamic than in colder sedimentary basins.

  1. Base hydrolysis and hydrothermal processing of PBX-9404 explosive

    SciTech Connect

    Sanchez, J.A.; Flesner, R.L.; Spontarelli, T.; Dell`Orco, P.C.; Kramer, J.F.

    1995-04-01

    Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, the authors examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. The authors also examine products from the subsequent hydrothermal treatment of the base hydrolysate. The gases produced from hydrolysis of PBX-9404 are ammonia, nitrous oxide, and nitrogen. Major aqueous products are sodium formate, acetate, nitrate, and nitrite, but not all carbon products have been identified. Hydrothermal processing of base hydrolysate destroyed up to 98% of the organic carbon in solution, and higher destruction efficiencies are possible. Major gas products detected from hydrothermal processing were nitrogen and nitrous oxide.

  2. Hydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming

    USGS Publications Warehouse

    Johnson, S.Y.; Stephenson, W.J.; Morgan, L.A.; Shanks, Wayne C.; Pierce, K.L.

    2003-01-01

    Yellowstone National Park is the site of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (???450 km) to document hydrothermal and tectonic features and deposits in northern Yellowstone Lake. Sublacustrine geothermal features in northern Yellowstone Lake include two of the largest known hydrothermal explosion craters, Mary Bay and Elliott's. Mary Bay explosion breccia is distributed uniformly around the crater, whereas Elliott's crater breccia has an asymmetric distribution and forms a distinctive, ???2-km-long, hummocky lobe on the lake floor. Hydrothermal vents and low-relief domes are abundant on the lake floor; their greatest abundance is in and near explosion craters and along linear fissures. Domed areas on the lake floor that are relatively unbreached (by vents) are considered the most likely sites of future large hydrothermal explosions. Four submerged shoreline terraces along the margins of northern Yellowstone Lake add to the Holocene record or postglacial lake-level fluctuations attributed to "heavy breathing" of the Yellowstone magma reservoir and associated geothermal system. The Lake Hotel fault cuts through northwestern Yellowstone Lake and represents part of a 25-km-long distributed extensional deformation zone. Three postglacial ruptures indicate a slip rate of ???0.27 to 0.34 mm/yr. The largest (3.0 m slip) and most recent event occurred in the past ???2100 yr. Although high heat flow in the crust limits the rupture area of this fault zone, future earthquakes of magnitude ???5.3 to 6.5 are possible. Earthquakes and hydrothermal explosions have probably triggered landslides, common features around the lake margins. Few high-resolution seismic reflection surveys have

  3. Catalytic hydrothermal processing of microalgae: decomposition and upgrading of lipids.

    PubMed

    Biller, P; Riley, R; Ross, A B

    2011-04-01

    Hydrothermal processing of high lipid feedstock such as microalgae is an alternative method of oil extraction which has obvious benefits for high moisture containing biomass. A range of microalgae and lipids extracted from terrestrial oil seed have been processed at 350 °C, at pressures of 150-200 bar in water. Hydrothermal liquefaction is shown to convert the triglycerides to fatty acids and alkanes in the presence of certain heterogeneous catalysts. This investigation has compared the composition of lipids and free fatty acids from solvent extraction to those from hydrothermal processing. The initial decomposition products include free fatty acids and glycerol, and the potential for de-oxygenation using heterogeneous catalysts has been investigated. The results indicate that the bio-crude yields from the liquefaction of microalgae were increased slightly with the use of heterogeneous catalysts but the higher heating value (HHV) and the level of de-oxygenation increased, by up to 10%.

  4. Hydrothermal activity on the Gorda Ridge

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.

    Near-bottom plumes of materials indicative of discharge of metal-rich hot springs were discovered at sites on the Gorda Ridge by a research team of government and university scientists on a cruise of the National Oceanic and Atmospheric Administration (NOAA) ship Surveyor during May 1985 as part of the NOAA Vents Program. The Gorda Ridge, off northern California and Oregon, is the only seafloor spreading center within the proclaimed 200-mile U.S. Exclusive Economic Zone (370 km wide) of the conterminous United States and is one of the last oceanic ridges to be explored for metal-rich hot springs. One reason for this neglect is that the Gorda Ridge is slow spreading, with half-rates ranging from 1.1 cm/yr in the southern portion to 2.2 cm/yr in the northern portion. Slow spreading centers have not been fully evaluated with regard to hydrothermal activity by many members of the research community, who have concentrated their attention on the faster spreading East Pacific Rise to the south and the Juan de Fuca Ridge to the north of the Gorda Ridge.

  5. Vein networks in hydrothermal systems provide constraints for the monitoring of active volcanoes.

    PubMed

    Cucci, Luigi; Di Luccio, Francesca; Esposito, Alessandra; Ventura, Guido

    2017-12-01

    Vein networks affect the hydrothermal systems of many volcanoes, and variations in their arrangement may precede hydrothermal and volcanic eruptions. However, the long-term evolution of vein networks is often unknown because data are lacking. We analyze two gypsum-filled vein networks affecting the hydrothermal field of the active Lipari volcanic Island (Italy) to reconstruct the dynamics of the hydrothermal processes. The older network (E1) consists of sub-vertical, N-S striking veins; the younger network (E2) consists of veins without a preferred strike and dip. E2 veins have larger aperture/length, fracture density, dilatancy, and finite extension than E1. The fluid overpressure of E2 is larger than that of E1 veins, whereas the hydraulic conductance is lower. The larger number of fracture intersections in E2 slows down the fluid movement, and favors fluid interference effects and pressurization. Depths of the E1 and E2 hydrothermal sources are 0.8 km and 4.6 km, respectively. The decrease in the fluid flux, depth of the hydrothermal source, and the pressurization increase in E2 are likely associated to a magma reservoir. The decrease of fluid discharge in hydrothermal fields may reflect pressurization at depth potentially preceding hydrothermal explosions. This has significant implications for the long-term monitoring strategy of volcanoes.

  6. Mineralogical, geochemical and isotopic characteristics of hydrothermal alteration processes in the active, submarine, felsic-hosted PACMANUS field, Manus Basin, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Lackschewitz, K. S.; Devey, C. W.; Stoffers, P.; Botz, R.; Eisenhauer, A.; Kummetz, M.; Schmidt, M.; Singer, A.

    2004-11-01

    During ODP Leg 193, 4 sites were drilled in the active PACMANUS hydrothermal field on the crest of the felsic Pual Ridge to examine the vertical and lateral variations in mineralization and alteration patterns. We present new data on clay mineral assemblages, clay and whole rock chemistry and clay mineral strontium and oxygen isotopic compositions of altered rocks from a site of diffuse low-temperature venting (Snowcap, Site 1188) and a site of high-temperature venting (Roman Ruins, Site 1189) in order to investigate the water-rock reactions and associated elemental exchanges. The volcanic succession at Snowcap has been hydrothermally altered, producing five alteration zones: (1) chlorite ± illite-cristobalite-plagioclase alteration apparently overprinted locally by pyrophyllite bleaching at temperatures of 260-310°C; (2) chlorite ± mixed-layer clay alteration at temperatures of 230°C; (3) chlorite and illite alteration; (4) illite and chlorite ± illite mixed-layer alteration at temperatures of 250-260°C; and (5) illite ± chlorite alteration at 290-300°C. Felsic rocks recovered from two holes (1189A and 1189B) at Roman Ruins, although very close together, show differing alteration features. Hole 1189A is characterized by a uniform chlorite-illite alteration formed at ˜250°C, overprinted by quartz veining at 350°C. In contrast, four alteration zones occur in Hole 1189B: (1) illite ± chlorite alteration formed at ˜300°C; (2) chlorite ± illite alteration at 235°C; (3) chlorite ± illite and mixed layer clay alteration; and (4) chlorite ± illite alteration at 220°C. Mass balance calculations indicate that the chloritization, illitization and bleaching (silica-pyrophyllite assemblages) alteration stages are accompanied by different chemical changes relative to a calculated pristine precursor lava. The element Cr appears to have a general enrichment in the altered samples from PACMANUS. The clay concentrate data show that Cr and Cu are predominantly

  7. Using Hydrothermal Plumes and Their Chemical Composition to Identify and Understand Hydrothermal Activity at Explorer Ridge

    NASA Astrophysics Data System (ADS)

    Resing, J.; Lebon, G.; Baker, E.; Walker, S.; Nakamura, K.; Silvers, B.

    2002-12-01

    During June and July, 2002, an extensive survey of the hydrothermal systems of the Explorer Ridge was made aboard the R/V Thomas Thompson. This survey employed hydrocasts and the Autonomous Benthic Explorer (ABE) to locate and map hydrothermal vent fields. A total of 28 hydrocasts (17 verticals and 11 tow-yos) were used to search for hydrothermal activity from 49.5°N to 50.3°N on the Explorer Ridge. During the hydrocasts continuous measurements were made of conductivity, temperature, pressure, light backscatter, eH, Fe, Mn, and pH. Discrete samples were collected for total dissolved Fe and Mn, methane, pH, total CO2, and particulate matter. Most of the strong hydrothermal venting was near the Magic Mountain area of the Explorer Ridge at ~49.76° N, 130.26° W, where strong particulate backscatter signals (~0.130 NTUs) and moderate temperature anomalies (~ 0.05 °C) were detected. The particulate matter causing the backscatter was made up primarily of volatile particulate sulfur (PS) with little to no hydrothermal PFe. PS:PFe ratios exceeded 25 in the areas of most intense venting, . These PFe and PS data suggest that the hydrothermal Fe, if any, is deposited as sulfide minerals beneath the sea floor and that S is far in excess of Fe in the hydrothermal fluids. In the most intense plumes,total dissolvable Fe and Mn were between 20 and 30 nM, pH anomalies exceeded 0.025 pH units (indicating an increase of ~10uM CO2), and methane reached 16nM. These results suggest that the fluids exiting the sea floor are metal-poor and moderately gas-rich.

  8. Interactions Between Serpentinization, Hydrothermal Activity and Microbial Community at the Lost City Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Delacour, A.; Frueh-Green, G. L.; Bernasconi, S. M.; Schaeffer, P.; Frank, M.; Gutjahr, M.; Kelley, D. S.

    2008-12-01

    Seafloor investigations of slow- and ultraslow-spreading ridges have reported many occurrences of exposed mantle peridotites and gabbroic rocks on the ocean floor. Along the Mid-Atlantic Ridge, these uplifted portions of oceanic crust host high-temperature black smoker-type hydrothermal systems (e.g., Rainbow, Logatchev, Saldanha), and the more distinct low-temperature Lost City Hydrothermal Field (LCHF). Built on a southern terrace of the Atlantis Massif, the LCHF is composed of carbonate-brucite chimneys that vent alkaline and low-temperature (40-90°C) hydrothermal fluids. These fluids are related to serpentinization of mantle peridotites, which together with minor gabbroic intrusions form the basement of the LCHF. Long-lived hydrothermal activity at Lost City led to extensive seawater-rock interaction in the basement rocks, as indicated by seawater-like Sr- and mantle to unradiogenic Nd-isotope compositions of the serpentinites. These high fluid fluxes in the southern part of the massif influenced the conditions of serpentinization and have obliterated the early chemical signatures in the serpentinites, especially those of carbon and sulfur. Compared to reducing conditions commonly formed during the first stages of serpentinization, serpentinization at Lost City is characterized by relatively oxidizing conditions resulting in a predominance of magnetite, the mobilization/dissolution and oxidation of igneous sulfides to secondary pyrite, and the incorporation of seawater sulfate, all leading to high bulk-rock S-isotope compositions. The Lost City hydrothermal fluids contain high concentrations in methane, hydrogen, and low-molecular weight hydrocarbons considered as being produced abiotically. In contrast, organic compounds in the serpentinites are dominated by the occurrences of isoprenoids (pristane, phytane, and squalane), polycyclic compounds (hopanes and steranes), and higher abundances of C16 to C20 n-alkanes indicative of a marine organic input. We

  9. Hydrothermal carbonization of animal manures: Processes and energetics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hydrothermal carbonization (HTC) is an emerging technology for thermochemically converting biomass and waste materials into value-added carbonaceous char called hydrochar. HTC is well suited to manage wet feedstocks streams because pre-drying prior to processing is not required as with gasification...

  10. Fast preparation of Bi{sub 2}GeO{sub 5} nanoflakes via a microwave-hydrothermal process and enhanced photocatalytic activity after loading with Ag nanoparticles

    SciTech Connect

    Li, Zhao-Qian; Lin, Xin-Shan; Zhang, Lei; Chen, Xue-Tai; Xue, Zi-Ling

    2012-09-15

    Highlights: ► Bi{sub 2}GeO{sub 5} nanoflakes were successfully synthesized via a microwave-assisted solution-phase approach. ► Ag nanoparticles were deposited on the Bi{sub 2}GeO{sub 5} nanoflakes by a photoreduction procedure. ► Catalytic activity of the Ag/Bi{sub 2}GeO{sub 5} nanocomposite in the photo-degradation of rhodamine B (RhB) was much higher than that of pure Bi{sub 2}GeO{sub 5}. -- Abstract: In this work, a facile and rapid microwave-assisted hydrothermal route has been developed to prepare Bi{sub 2}GeO{sub 5} nanoflakes. Ag nanoparticles were subsequently deposited on the Bi{sub 2}GeO{sub 5} nanoflakes by a photoreduction procedure. The phases and morphologies of the products were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy. Photocatalytic experiments indicate that such Ag/Bi{sub 2}GeO{sub 5} nanocomposite possesses higher photocatalytic activity for RhB degradation under UV light irradiation in comparison to pure Bi{sub 2}GeO{sub 5}. The amount of Ag in the nanocomposite affects the catalytic activity, and 3 wt% Ag showed the highest photodegradation efficiency. Moreover, the catalyst remains active after four consecutive tests. The present study provides a new strategy to design composite materials with enhanced photocatalytic activity.

  11. Hydrothermal alkali metal catalyst recovery process

    DOEpatents

    Eakman, James M.; Clavenna, LeRoy R.

    1979-01-01

    In a coal gasification operation or similar conversion process carried out in the presence of an alkali metal-containing catalyst wherein solid particles containing alkali metal residues are produced, alkali metal constituents are recovered from the particles primarily in the form of water soluble alkali metal formates by treating the particles with a calcium or magnesium-containing compound in the presence of water at a temperature between about 250.degree. F. and about 700.degree. F. and in the presence of added carbon monoxide. During the treating process the water insoluble alkali metal compounds comprising the insoluble alkali metal residues are converted into water soluble alkali metal formates. The resultant aqueous solution containing water soluble alkali metal formates is then separated from the treated particles and any insoluble materials formed during the treatment process, and recycled to the gasification process where the alkali metal formates serve as at least a portion of the alkali metal constituents which comprise the alkali metal-containing catalyst. This process permits increased recovery of alkali metal constituents, thereby decreasing the overall cost of the gasification process by reducing the amount of makeup alkali metal compounds necessary.

  12. Hydrothermal carbonization: process water characterization and effects of water recirculation.

    PubMed

    Stemann, Jan; Putschew, Anke; Ziegler, Felix

    2013-09-01

    Poplar wood chips were treated hydrothermally and the increase of process efficiency by water recirculation was examined. About 15% of the carbon in the biomass was dissolved in the liquid phase when biomass was treated in de-ionized water at 220 °C for 4 h. The dissolved organic matter contained oxygen and was partly aerobically biodegradable. About 30-50% of the total organic carbon originated from organic acids. A polar and aromatic fraction was extracted and a major portion of the organic load was of higher molecular weight. By process water recirculation organic acids in the liquid phase concentrated and catalyzed dehydration reactions. As a consequence, functional groups in hydrothermally synthesized coal declined and dewaterability was enhanced. Recirculated reactive substances polymerized and formed additional solid substance. As a result, carbon and energetic yields of the produced coal rose to 84% and 82%, respectively.

  13. The Sasquatch Hydrothermal Field: Linkages Between Seismic Activity, Hydrothermal Flow, and Geology

    NASA Astrophysics Data System (ADS)

    Glickson, D. A.; Kelley, D. S.; Delaney, J. R.

    2006-12-01

    The Sasquatch Hydrothermal Field is the most northern known vent field along the central Endeavour Segment of the Juan de Fuca Ridge, located 6 km north of the Main Endeavour Field (MEF) near 47° 59.8'N, 129° 4.0'W. It was discovered in 2000, after two large earthquake swarms in June 1999 and January 2000 caused increased venting temperatures in the MEF and significant changes in volatile composition along the entire axis [Johnson et al., 2000; Lilley et al., 2003; Proskurowski et al., 2004]. From 2004-2006, Sasquatch and the surrounding axial valley were comprehensively mapped with SM2000 multibeam sonar system and Imagenex scanning sonar at a resolution of 1-5 m. These data were combined with visual imagery from Alvin and ROV dives to define the eruptive, hydrothermal, and tectonic characteristics of the field and distal areas. Based on multibeam sonar results, bathymetric relief of the segment near Sasquatch is subdued. The broad axial valley is split by a central high that rises 30-40 m above the surrounding seafloor. Simple pattern analysis of the valley shows two fundamentally different regions, distinguished by low and high local variance. Areas of low variance correspond to a collapse/drainback landscape characterized by ropy sheet flow, basalt pillars, and bathtub rings capped by intact and drained lobate flows. Areas of high variance generally correspond to three types of ridge structures: 1) faulted basalt ridges composed of truncated pillow basalt, rare massive flows, and widespread pillow talus; 2) constructional basalt ridges composed of intact pillow flow fronts; and 3) extinct sulfide ridges covered by varying amounts of sulfide talus and oxidized hydrothermal sediment. Sasquatch is located in a depression among truncated pillow ridges, and is comprised of ~10, 1-6 m high, fragile sulfide chimneys that vent fluids up to 289°C. The active field extends only ~25 x 25 m, although a linear, N-S trending ridge of nearly continuous extinct sulfide

  14. Chemical reaction path modeling of hydrothermal processes on Mars: Preliminary results

    NASA Technical Reports Server (NTRS)

    Plumlee, Geoffrey S.; Ridley, W. Ian

    1992-01-01

    Hydrothermal processes are thought to have had significant roles in the development of surficial mineralogies and morphological features on Mars. For example, a significant proportion of the Martian soil could consist of the erosional products of hydrothermally altered impact melt sheets. In this model, impact-driven, vapor-dominated hydrothermal systems hydrothermally altered the surrounding rocks and transported volatiles such as S and Cl to the surface. Further support for impact-driven hydrothermal alteration on Mars was provided by studies of the Ries crater, Germany, where suevite deposits were extensively altered to montmorillonite clays by inferred low-temperature (100-130 C) hydrothermal fluids. It was also suggested that surface outflow from both impact-driven and volcano-driven hydrothermal systems could generate the valley networks, thereby eliminating the need for an early warm wet climate. We use computer-driven chemical reaction path calculation to model chemical processes which were likely associated with postulated Martian hydrothermal systems.

  15. Hydrothermal Activity and Volcanism on the Southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Haase, K. M.; Scientific Party, M.

    2005-12-01

    In April 2005 four recently discovered different hydrothermal fields on the slow-spreading Mid-Atlantic Ridge (MAR) south of the Equator were studied and sampled using a remotely operated vehicle (ROV) during cruise METEOR 64/1. Three of these hydrothermally active fields (called Turtle Pits, Red Lion, and Wideawake) occur at about 3000 m water depth in the centre of a MAR segment at 4° 48'S which appears to be volcanically very active. The youngest lava flow partly covers the low-temperature, diffuse flow Wideawake mussel field and is thus probably only a few years old. The high-temperature Turtle Pits hydrothermal field with four active vent structures lies some 300 m west of the diffuse vent field and is characterized by boiling fluids with temperatures close to 400° C. The mineral assemblage recovered from inactive hydrothermal mounds includes massive magnetite+hematite+sulfate and differs from that of the presently active vents and indicates more oxidizing conditions during the earlier activity. The vent fluids at Turtle Pits contain relatively high contents of hydrogen which may have formed during iron oxidation processes when basaltic magmas crystallized. The high fluid temperatures, the change to more reducing conditions, and the relatively high hydrogen contents in the fluids are most likely due to the ascent of magmas from the mantle that fed the very recent eruption. The high-temperature Red Lion hydrothermal field lies some 2 km north of the Turtle Pits field and consists of at least four active black smokers surrounded by several inactive sulfide mounds. The composition of the Red Lion fluids differs significantly from the Turtle Pits fluids, possibly owing largely to a difference in the temperature of the two systems. The fourth hydrothermally active field on the southern MAR, the Liliput field, was discovered near 9° 33'S in a water depth of 1500 m and consists of several low-temperature vents. A shallow hydrothermal plume in the water column

  16. Genifuel Hydrothermal Processing Bench Scale Technology Evaluation Project (WE&RF Report LIFT6T14)

    EPA Science Inventory

    Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of the Genifuel hydrothermal process technology for handling municipal wastewater sludge. HTL tests were conducted at 300-350◦C ...

  17. Hydrothermal activity at the Arctic mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Pedersen, Rolf B.; Thorseth, Ingunn H.; Nygård, Tor Eivind; Lilley, Marvin D.; Kelley, Deborah S.

    Over the last 10 years, hydrothermal activity has been shown to be abundant at the ultraslow spreading Arctic Mid-Ocean Ridges (AMOR). Approximately 20 active and extinct vent sites have been located either at the seafloor, as seawater anomalies, or by dredge sampling hydrothermal deposits. Decreasing spreading rates and decreasing influence of the Icelandic hot spot toward the north along the AMOR result in a north-south change from a shallow and magmatically robust to a deep and magmatically starved ridge system. This contrast gives rise to large variability in the ridge geology and in the nature of the associated hydrothermal systems. The known vent sites at the southern part of the ridge system are either low-temperature or white smoker fields. At the deep, northern parts of the ridge system, a large black smoker field has been located, and seawater anomalies and sulfide deposits suggest that black smoker-type venting is common. Several of these fields may be peridotite-hosted. The hydrothermal activity at parts of the AMOR exceeds by a factor of 2 to 3 what would be expected by extrapolating from observations on faster spreading ridges. Higher fracture/fault area relative to the magma volume extracted seems a likely explanation for this. Many of the vent fields at the AMOR are associated with axial volcanic ridges. Strong focusing of magma toward these ridges, deep rifting of the ridges, and subsequent formation of long-lived detachment faults that are rooted below the ridges may be the major geodynamic mechanisms causing the unexpectedly high hydrothermal activity.

  18. Hydrothermal Processing of Macroalgal Feedstocks in Continuous-Flow Reactors

    SciTech Connect

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Rotness, Leslie J.; Roesijadi, Guri; Zacher, Alan H.; Magnuson, Jon K.

    2014-02-03

    Wet macroalgal slurries have been converted into a biocrude by hydrothermal liquefaction (HTL) in a bench-scale continuous-flow reactor system. Carbon conversion to a gravity-separable oil product of 58.8% was accomplished at relatively low temperature (350 °C) in a pressurized (subcritical liquid water) environment (20 MPa) when using feedstock slurries with a 21.7% concentration of dry solids. As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent, and biomass trace mineral components were removed by processing steps so that they did not cause processing difficulties. In addition, catalytic hydrothermal gasification (CHG) was effectively applied for HTL byproduct water cleanup and fuel gas production from water-soluble organics. Conversion of 99.2% of the carbon left in the aqueous phase was demonstrated. Finally, as a result, high conversion of macroalgae to liquid and gas fuel products was found with low levels of residual organic contamination in byproduct water. Both process steps were accomplished in continuous-flow reactor systems such that design data for process scale-up was generated.

  19. Hydrothermal liquefaction of biomass: Developments from batch to continuous process

    SciTech Connect

    Elliott, Douglas C.; Biller, Patrick; Ross, Andrew; Schmidt, Andrew J.; Jones, Susanne B.

    2015-02-01

    This review describes the recent results in hydrothermal liquefaction (HTL) of biomass in continuous-flow processing systems. Although much has been published about batch reactor tests of biomass HTL, there is only limited information yet available on continuous-flow tests, which can provide a more reasonable basis for process design and scale-up for commercialization. High-moisture biomass feedstocks are the most likely to be used in HTL. These materials are described and results of their processing are discussed. Engineered systems for HTL are described however they are of limited size and do not yet approach a demonstration scale of operation. With the results available process models have been developed and mass and energy balances determined. From these models process costs have been calculated and provide some optimism as to the commercial likelihood of the technology.

  20. Hydrothermal liquefaction of biomass: developments from batch to continuous process.

    PubMed

    Elliott, Douglas C; Biller, Patrick; Ross, Andrew B; Schmidt, Andrew J; Jones, Susanne B

    2015-02-01

    This review describes the recent results in hydrothermal liquefaction (HTL) of biomass in continuous-flow processing systems. Although much has been published about batch reactor tests of biomass HTL, there is only limited information yet available on continuous-flow tests, which can provide a more reasonable basis for process design and scale-up for commercialization. High-moisture biomass feedstocks are the most likely to be used in HTL. These materials are described and results of their processing are discussed. Engineered systems for HTL are described; however, they are of limited size and do not yet approach a demonstration scale of operation. With the results available, process models have been developed, and mass and energy balances determined. From these models, process costs have been calculated and provide some optimism as to the commercial likelihood of the technology.

  1. Hydrothermal activity at the Trans-Atlantic Geotraverse Hydrothermal Field, Mid-Atlantic Ridge crest at 26°N

    NASA Astrophysics Data System (ADS)

    Rona, P. A.; Thompson, G.; Mottl, M. J.; Karson, J. A.; Jenkins, W. J.; Graham, D.; Mallette, M.; von Damm, K.; Edmond, J. M.

    1984-12-01

    The first submersible observations of the only known active submarine hydrothermal field on a slow-spreading oceanic ridge are incorporated with results of 10 prior years of investigation to derive an understanding of periodicity, duration, and varying intensity of hydrothermal activity at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge crest near latitude 26°N. Hydrothermal activity has persisted at this location for at least 1×106 years based on the distribution of hydrothermal and hydrogenous mineralization with respect to crustal age. The hydrothermal activity has been cyclic, multistage, and episodic. Prior high-temperature hydrothermal venting stages with a periodicity of the order of 1×104 years and duration of the order of 101 years are deduced from the estimated ages of discrete sedimentary layers anomalously enriched in Cu, Fe, and Zn and correspond with the independently determined periodicity of volcanic eruptive cycles on the Mid-Atlantic Ridge. The most recent episode of high-temperature venting is inferred to have ceased in the recent past based on metal enrichment (Cu, Fe, Zn) in the surficial sediment layer. Low-temperature hydrothermal venting stages with a duration of the order of 1×104 years intervene between the short high-temperature stages and produce stratiform deposits of layered and earthy manganese oxide, iron oxide, hydroxide, and silicate. Bivalve-like forms with the characteristics of vent clams in various stages of dissolution are identified on bottom photographs. The fresh appearance of intact tubules composed of iron hydroxide that acted as vents on relict deposits, conductive heat flow anomalies in the sediment column, and the record of temperature anomalies and excess 3He in the near-bottom water column, suggest that the low-temperature hydrothermal discharge is intermittent at individual vents on a time scale of years.

  2. Influence of process water quality on hydrothermal carbonization of cellulose.

    PubMed

    Lu, Xiaowei; Flora, Joseph R V; Berge, Nicole D

    2014-02-01

    Hydrothermal carbonization (HTC) is a thermal conversion process that has been shown to be environmentally and energetically advantageous for the conversion of wet feedstocks. Supplemental moisture, usually in the form of pure water, is added during carbonization to achieve feedstock submersion. To improve process sustainability, it is important to consider alternative supplemental moisture sources. Liquid waste streams may be ideal alternative liquid source candidates. Experiments were conducted to systematically evaluate how changes in pH, ionic strength, and organic carbon content of the initial process water influences cellulose carbonization. Results from the experiments conducted evaluating the influence of process water quality on carbonization indicate that changes in initial water quality do influence time-dependent carbonization product composition and yields. These results also suggest that using municipal and industrial wastewaters, with the exception of streams with high CaCl2 concentrations, may impart little influence on final carbonization products/yields.

  3. Hydrothermal regimes of the dry active layer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Mamoru; Zhang, Yinsheng; Kadota, Tsutomu; Ohata, Tetsuo

    2006-04-01

    Evaporation and condensation in the soil column clearly influence year-round nonconductive heat transfer dynamics in the dry active layer underlying semiarid permafrost regions. We deduced this from heat flux components quantified using state-of-the-art micrometeorological data sets obtained in dry and moist summers and in winters with various snow cover depths. Vapor moves easily through large pores, some of which connect to the atmosphere, allowing (1) considerable active layer warming driven by pipe-like snowmelt infiltration, and (2) direct vapor linkage between atmosphere and deeper soils. Because of strong adhesive forces, water in the dry active layer evaporates with great difficulty. The fraction of latent heat to total soil heat storage ranged from 26 to 45% in dry and moist summers, respectively. These values are not negligible, despite being smaller than those of arctic wet active layer, in which only freezing and thawing were considered.

  4. High-Pressure Hydrothermal Processing in Large Icy Satellites

    NASA Astrophysics Data System (ADS)

    Scott, H. P.; Hemley, R. J.; Ryerson, F. J.; Williams, Q.

    2002-12-01

    We have conducted a series of experiments designed to simulate chemical processes within large icy satellites. Few phase equilibria data exist which are relevant to the chemical evolution of moons such as Jupiter's Europa and Ganymede, Saturn's Titan and Neptune's Triton; however, models of their interiors are critically dependent on their internal chemistry and density. An internally generated magnetic field has been observed for Ganymede which implies the existence of a liquid metallic core, and accordingly an interior temperature exceeding 1000ṡC. This observation, coupled with the known abundance of water ice on Ganymede, suggests that rock - water interactions at high temperatures and pressures (prospectively in the past) would control the interior mineralogy of these satellites. Additionally, organic material has been observed on the surface of Ganymede, and in conjunction with the large complement of water ice, it has been suggested that icy satellites possess the prerequisites for life to originate; however, the stability of organic material under high-pressure hydrothermal processing is unclear. We used a piston-cylinder press to react material of carbonaceous chondrite chemistry with H2O at a range of temperatures and oxidation states at a pressure of 1.5 GPa, and make the following observations: 1) At temperatures below ~850ṡC the density of the rock interior will be largely that of hydrated ferromagnesian silicates (serpentine - chlorite - talc depending on temperature and oxidation state), 2) Iron and sulfur alloy readily under these conditions, forming the mineral pyrrhotite -- a metallic core of this chemistry is therefore likely, and 3) Hydrothermal processing of organic species of carbon at temperatures above 450ṡC produces carbonate minerals -- the prerequisite materials for life are not preserved deep within icy satellites. To further investigate the high-pressure hydrothermal processing of organic material we are conducting experiments

  5. Refractory Organic Compounds in Enceladus' Ice Grains and Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    Postberg, F.; Khawaja, N.; Hsu, H. W.; Sekine, Y.; Shibuya, T.

    2015-12-01

    Cassini's Cosmic Dust Analyzer (CDA) generates time-of-flight mass spectra of individual grains impinging on the instruments target-plate. Following the analysis of salt rich ice grains emitted by Enceladus that indicated a salt-water ocean in contact with the moon's rocky core [1,2] a recent CDA analysis of nano-phase silica particles pointed at hydrothermal activity at the moon's rock/water interface [3]. The results imply temperatures above 80 - 90°C and alkaline pH values around 10 reminiscent of alkaline hydrothermal vents on Earth like the Lost City Hydrothermal Field. In this context the compositional analysis of organic components in CDA mass spectra of the ejected ice grains is of particular relevance. A multitude of volatile organic species has already been identified in the gas component of the plume [4]. As expected, we find more complex organic molecules in ice grains than in the gas indicating aromatic species, amines, and carbonyl group species. The composition of organic-bearing ice grains displays a great diversity indicating a variety of different organic species in varying concentrations. Recent spatially resolved CDA in situ measurements inside Enceladus' plume indicate that these organic compounds are especially frequent in 'young' ice grains that have just been ejected by high velocity jets. We investigate the implications of our findings with respect to ice grain formation at the water surface and inside the icy vents. We constrain the generation of organic compounds at the rock/water interface in the light of hydrothermal activity and the potential for the formation of life precursor molecules in Enceladus' ocean. Ref:[1] Postberg et al., Nature 459, 1098-1101 (2009). [2] Postberg et al., Nature 474, 620-622 (2011). [3]. Hsu, Postberg, Sekine et al., Nature, 519, 207-210 (2015). [4] Waite et al., Nature 460, 487-490 (2009).

  6. Transport Processes in Reacting Hydrothermal Flames with Applications to Military Waste Destruction in Supercritical Water and Geotechnical Rock Excavation

    DTIC Science & Technology

    2009-01-01

    Transport Processes in Reacting Hydrothermal Flames with Applications to Military Waste Destruction in Supercritical Water and... Hydrothermal Burner Reactor System ...................................................... 2  3. Hydrothermal flame experiments... Hydrothermal Flames with Applications to Military Waste Destruction in Supercritical Water and Geotechnical Rock Excavation 5a. CONTRACT NUMBER W911NF-05

  7. Processing of Microalgae: Acoustic Cavitation and Hydrothermal Conversion

    NASA Astrophysics Data System (ADS)

    Greenly, Justin Michael

    The production of energy dense fuels from renewable algal biomass feedstocks -- if sustainably developed at a sufficiently large scale -- may reduce the consumption of petroleum from fossil fuels and provide many environmental benefits. Achieving economic feasibility has several technical engineering challenges that arise from dilute concentration of growing algae in aqueous media, small cell sizes, and durable cell walls. For microalgae to be a sustainable source of biofuels and co-products, efficient fractionation and conversion of the cellular contents is necessary. Research was carried out to address two processing options for efficient microalgae biofuel production: 1. Ultrasonic cavitation for cell disruption and 2. Hydrothermal conversion of a model algal triglyceride. 1. Ultrasonic cell disruption, which relies on cavitating bubbles in the suspension to produce damaging shock waves, was investigated experimentally over a range of concentrations and species types. A few seconds of high intensity sonication at fixed frequency yielded significant cell disruption, even for the more durable cells. At longer exposure times, effectiveness was seen to decline and was attributed, using acoustic measurements, to ultrasonic power attenuation in the ensuing cloud of cavitating bubbles. Processing at higher cell concentrations slowed cell disintegration marginally, but increased the effectiveness of dissipating ultrasonic energy. A theoretical study effectively predicted optimal conditions for a variety of parameters that were inaccessible in this experimental investigation. In that study, single bubble collapse was modeled to identify operating conditions that would increase cavitation, and thus cell disruption. Simulations were conducted by varying frequency and pressure amplitude of the ultrasound wave, and initial bubble size. The simulation results indicated that low frequency, high sound wave amplitudes, and small initial bubble size generate the highest shock

  8. Numerical Simulation of Hydrothermal Salt Separation Process and Analysis and Cost Estimating of Shipboard Liquid Waste Disposal

    DTIC Science & Technology

    2007-06-01

    which are investigating methods to produce energy from waste . One particular process being investigated is a hydrothermal process which converts...Bio-fuels motivation Another application for hydrothermal treatment is a catalytic reaction process where a variety of biomass feedstocks...the hydrothermal biomass gasification process are twofold. First, salts which can interfere with the catalytic conversion process of the organic

  9. Physical inter-relationships between hydrothermal activity, faulting and magmatic processes at the center of a slow-spreading, magma-rich mid-ocean ridge segment: A case study of the Lucky Strike segment (MAR, 37°03'-37‧N)

    NASA Astrophysics Data System (ADS)

    Fontaine, F. J.; Cannat, M.; Escartin, J.; Crawford, W. C.; Singh, S. C.

    2012-12-01

    The modalities and efficiency of hydrothermal heat evacuation at mid-ocean ridges (25% of the global heat loss) are controlled by the lithosphere thermal and permeability structures for which we had robust constraints only for fast/intermediate spreading axis until the last past few years during which integrated geophysical, geological and geochemical studies focused on some hydrothermal sites at slow-spreading ridges. At the Lucky Strike vent field of the mid-atlantic ridge - a hydrothermal complex composed of high-temperature (maximum T=340°C), smoker-like vents and associated diffuse flow and extracting a few hundreds MW from the oceanic lithosphere - a seafloor observatory which installation started in 2005 highlights local interactions between hydrothermal, tectonic and magmatic processes. Detailed geophysical and geological investigations stress the role of the local axial fault system on localizing high- and low-temperature ventings around the faulted rim of a paleo lava lake. Microseismic studies bring constraints on the subseafloor hydrology and suggest an along-axis flow pattern, with a privileged recharge area located about a kilometer north off the active discharges. Seismic reflection studies image a central magma chamber fueling the hydrothermal sites and also reveal its along-axis depth variations likely influencing hydrothermal cell organization and flow focusing. Such linkages among hydrothermal dynamics, heat source and crustal permeability geometries usually lack quantitative constraints at mid-ocean ridges in general, and the Lucky Strike segment settings offers a unique opportunity to couple high-resolution geophysical data to hydrodynamic model. Here we develop a series of original two- and three-dimensional numerical and physical models of hydrothermal activity, tailored to this slow-spreading environment. Our results highlight physical linkages among magmatism, tectonics and crustal hydrology stressing the key role of faulting and magma

  10. An authoritative global database for active submarine hydrothermal vent fields

    NASA Astrophysics Data System (ADS)

    Beaulieu, Stace E.; Baker, Edward T.; German, Christopher R.; Maffei, Andrew

    2013-11-01

    The InterRidge Vents Database is available online as the authoritative reference for locations of active submarine hydrothermal vent fields. Here we describe the revision of the database to an open source content management system and conduct a meta-analysis of the global distribution of known active vent fields. The number of known active vent fields has almost doubled in the past decade (521 as of year 2009), with about half visually confirmed and others inferred active from physical and chemical clues. Although previously known mainly from mid-ocean ridges (MORs), active vent fields at MORs now comprise only half of the total known, with about a quarter each now known at volcanic arcs and back-arc spreading centers. Discoveries in arc and back-arc settings resulted in an increase in known vent fields within exclusive economic zones, consequently reducing the proportion known in high seas to one third. The increase in known vent fields reflects a number of factors, including increased national and commercial interests in seafloor hydrothermal deposits as mineral resources. The purpose of the database now extends beyond academic research and education and into marine policy and management, with at least 18% of known vent fields in areas granted or pending applications for mineral prospecting and 8% in marine protected areas.

  11. Engineering carbon materials from the hydrothermal carbonization process of biomass.

    PubMed

    Hu, Bo; Wang, Kan; Wu, Liheng; Yu, Shu-Hong; Antonietti, Markus; Titirici, Maria-Magdalena

    2010-02-16

    Energy shortage, environmental crisis, and developing customer demands have driven people to find facile, low-cost, environmentally friendly, and nontoxic routes to produce novel functional materials that can be commercialized in the near future. Amongst various techniques, the hydrothermal carbonization (HTC) process of biomass (either of isolated carbohydrates or crude plants) is a promising candidate for the synthesis of novel carbon-based materials with a wide variety of potential applications. In this Review, we will discuss various synthetic routes towards such novel carbon-based materials or composites via the HTC process of biomass. Furthermore, factors that influence the carbonization process will be analyzed and the special chemical/physical properties of the final products will be discussed. Despite the lack of a clear mechanism, these novel carbonaceous materials have already shown promising applications in many fields such as carbon fixation, water purification, fuel cell catalysis, energy storage, CO(2) sequestration, bioimaging, drug delivery, and gas sensors. Some of the most promising examples will also be discussed here, demonstrating that the HTC process can rationally design a rich family of carbonaceous and hybrid functional carbon materials with important applications in a sustainable fashion.

  12. Post-drilling hydrothermal vent and associated biological activities seen through artificial hydrothermal vents in the Iheya North field, Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Takai, K.; Kawagucci, S.; Miyazaki, J.; Watsuji, T.; Ishibashi, J.; Yamamoto, H.; Nozaki, T.; Kashiwabara, T.; Shibuya, T.

    2012-12-01

    In 2010, IODP Expedition 331 was conducted in the Iheya North Field, the Okinawa Trough and drilled several sites in hydrothermally active subseafloor. In addition, during the IODP Expedition 331, four new hydrothermal vents were created. These post-drilling artificial hydrothermal vents provide excellent opportunities to investigate the physical, chemical and microbiological characteristics of the previously unexplored subseafloor hydrothermal fluid reservoirs, and to monitor and estimate how the anthropogenic drilling behaviors affect the deep-sea hydrothermal vent ecosystem. We were very much interested in the difference of hydrothermal fluid chemistry between the natural hydrothermal vents and the artificial hydrothermal vents. The IODP porewater chemistry of the cores pointed to the density-driven stratification of the phase-separated hydrothermal fluids and the natural vent fluids were likely derived only from the shallower vapor-enriched phases. However, the artificial hydrothermal vents had deeper fluid sources in the subseafloor hydrothermal fluid reservoirs composed of vapor-lost (Cl-enriched) phases. The fluids from the artificial hydrothermal vents were sampled by ROV at 5, 12 and 18 months after the IODP expedition. The artificial hydrothermal vent fluids were slightly enriched with Cl as compared to the natural hydrothermal vent fluids. Thus, the artificial hydrothermal vents successfully entrained the previously unexplored subseafloor hydrothermal fluids. The newly created hydrothermal vents also hosted the very quickly grown, enormous chimney structures, of which mineral compositions were highly variable among the vents. However, the quickly grown C0016B and C0016D vent chimneys were found to be typical Kuroko ore even though the chimney growth rates in the artificial vents were extremely faster than those in the natural vents. In addition, the IODP drilling operation not only created new hydrothermal vents by deep drilling but also induced the

  13. The study of active submarine volcanoes and hydrothermal vents in the Southernmost Part of Okinawa Trough

    NASA Astrophysics Data System (ADS)

    Lee, Y.; Tsai, C.; Lee, C.

    2004-12-01

    The study area is located in the Southernmost Part of Okinawa Trough (SPOT), which is a back-arc basin formed by extension of Eurasian plate. Previous research indicated two extensional stages in SPOT area. Many normal-fault structures were come into existence during both extensional processes. The SPOT is presently in an activity tectonic episode. Therefore, the area becomes a frequent earthquake and abundant magmatism. The purpose of this study is to discuss which relationship between tectonics, submarine volcanoes and hydrothermal vents in SPOT area. The investigations are continued from 1998 to 2004, we have found at least twelve active hydrothermal vents in study area. Compare the locations hydrothermal vents with fault systems, we find both of them have highly correlated. We can distinguish them into two shapes, pyramidal shape and non-pyramidal shape. According to plumes height, we are able to divide these vents into two groups near east longitude 122.5° . East of this longitude, the hydrothermal plumes are more powerful and west of it are the weaker. This is closely related to the present extensional axis (N80° E) of the southern part of the Okinawa Trough. This can be explained the reason of why the more powerful vents coming out of the east group. The east group is associated with the present back-arc spreading system. West of 122.5° , the spreading system are in a primary stage. The andesitic volcanic island, the Turtle Island, is a result of N60° E extensional tectonism with a lot of faults. Besides the pyramidal shape, this can be proved indirectly. The vents located in the west side were occurred from previous extensional faults and are weaker than the eastern. Therefore, we suggest that if last the extension keeps going on, the hydrothermal vents located at the west side of the longitude 122.5° will be intensified.

  14. Tidal Evolution and Hydrothermal Activity in IcyWorlds

    NASA Astrophysics Data System (ADS)

    Vance, S.; Hussmann, H.

    2008-09-01

    The tidal heating that sustains a subsurface ocean in Europa likely varied in intensity through the moons history due to the exchange of orbital angular momentum with the innermost Galilean satellite, Io [1]. Tidal interactions elsewhere in the solar system — e.g. in Neptunes moon Triton, and in Kuiper belt systems such as Pluto-Charon and the 2003 EL61 system (Santa-Rudolph-Blitzen) — highlight the potential for vigorously heated subsurface oceans and thus the existence of hydrothermal systems in icy worlds. Understanding the extent and nature of hydrothermal activity in such systems is important for assessing the availability of essential elements and organic compounds necessary sustain and, possibly, originate life [2, 3, 4, 5, 6, 7]. During periods of low tidal heating in such systems, hydrothermalism driven by serpentinization (reaction of water with ultramafic rock) may be extensive, with implications for seafloor production of hydrogen, methane and other potential nutrients, and elements necessary to originate and support life in icy world oceans. For Enceladus, an anomalously dense satellite for its size, radiogenic heating and overburden pressure in the mantle are sufficiently low to permit fracturing of the entirety of the moons rocky interior on long time scales [8]. Estimates of methane production from serpentinization of Enceladus interior, based on measured fluxes from the Lost City Hydrothermal Field [9], are an order of magnitude greater than fluxes observed at Enceladuss south polar plume by the Cassini Ion Neutral Mass Spectrometer [10]. For the largest icy worlds in the Solar System — Titan, Ganymede and Callisto—pressures at and below the H2Orock interface are likely too high to permit the formation of microfractures, so an alternative explanation is required if methane is endogenous. Aqueous alteration may be augmented from the above estimates if altered crust is rejuvenated during periods of increased tidal dissipation. Crustal

  15. Hydrothermal Activity on the Southern Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    German, C. R.; Connelly, D. P.; Evans, A. J.; Parson, L. M.

    2002-12-01

    close to a vent-site because this plume is particle laden as well as containing significant TDMn anomalies. Equivalent signals from the Broken Spur or SnakePit hydrothermal plumes (29N and 23N, MAR respectively) are only observed within 2-5km of those active vent-sites (German et al., Deep Sea Res. 1999).

  16. Active hydrothermal and non-active massive sulfide mound investigation using a new multiparameter chemical sensor

    NASA Astrophysics Data System (ADS)

    Han, C.; Wu, G.; Qin, H.; Wang, Z.

    2012-12-01

    Investigation of active hydrothermal mound as well as non-active massive sulfide mound are studied recently. However, there is still lack of in-situ detection method for the non-active massive sulfide mound. Even though Transient ElectroMagnetic (TEM) and Electric Self-potential (SP) methods are good, they both are labour, time and money cost work. We proposed a new multiparameter chemical sensor method to study the seafloor active hydrothermal mound as well as non-active massive sulfide mound. This sensor integrates Eh, S2- ions concentration and pH electrochemical electrodes together, and could found chemical change caused by the active hydrothermal vent, even weak chemical abnormalities by non-active massive sulfide hydrothermal mound which MARP and CTD sometimes cannot detect. In 2012, the 1st Leg of the Chinese 26th cruise, the multiparameter chemical sensor was carried out with the deepsea camera system over the Carlsberg Ridge in Indian Ocean by R/V DAYANGYIHAO. It was shown small Eh and S2- ions concentration abnormal around a site at Northwest Indian ridge. This site was also evidenced by the TV grab. In the 2nd Leg of the same cruise in June, this chemical sensor was carried out with TEM and SP survey system. The chemical abnormalities are matched very well with both TEM and SP survey results. The results show that the multiparameter chemical sensor method not only can detect active hydrothermal mound, but also can find the non-active massive sulfide hydrothermal mound.

  17. Seafloor Hydrothermal Activity in the Southern Gulf of California

    NASA Astrophysics Data System (ADS)

    Paduan, J. B.; Clague, D. A.; Caress, D. W.; Lundsten, L.; Zierenberg, R. A.; Troni, G.; Wheat, C. G.; Spelz, R. M.

    2015-12-01

    Active hydrothermal venting was previously unknown between Guaymas Basin and 21°N on the East Pacific Rise. MBARI AUV surveys and ROV dives in 2012 and 2015 discovered 7 hydrothermal vent sites with diverse and varied vent communities within that gap. One field in the Pescadero Basin vents clear shimmering fluids at 3685 m depth and four vigorous black smoker fields and several extinct chimney fields are between 2225 and 2400 m depth on the Alarcón Rise. Low-temperature vent sites are present on both of the Pescadero and Tamayo Transforms. The chimneys were discovered in 1-m resolution AUV bathymetric data, with some indicated to be active based on temperature anomalies in the AUV CTD data and confirmed during later ROV dives. The low-temperature vent sites on the transform faults were found on ROV dives while exploring young lava flows and sediment hills uplifted by sill intrusions. Pescadero Basin is a deep extensional basin in the southern Gulf. The smooth, subtly faulted floor is filled with at least 150 m of sediment, as determined from sub-bottom profiles collected by the AUV. Three large chimneys (named Auka by our Mexican collaborators) and several broad mounds are located on the SW margin of the basin. Temperatures to 290°C were measured, the fluids are clear, neutral pH, and contain elevated Na. The chimneys are delicate, white, predominantly Ca-carbonate; barite, sparse sulfides, and some aromatic hydrocarbons are also present. Three active vent fields (Ja Sít, Pericú, and Meyibó) at Alarcón Rise are located near the eruptive fissure of an extensive young sheet flow. The fourth field (Tzab-ek) is 1.1 km NW of the axis on older pillow lavas. The largest chimneys are in the Tzab-ek field: 31 and 33 m tall, with flanges and upside-down waterfalls. They rise from a sulfide mound, suggesting a long-lived hydrothermal system, in contrast to the near-axis fields where the chimneys grow directly on basalt. The Alarcón chimneys are Zn and Cu-rich sulfides

  18. Searching for evidence of hydrothermal activity at Apollinaris Mons, Mars

    USGS Publications Warehouse

    El Maarry, M.R.; Dohm, J.M.; Marzo, G.A.; Fergason, R.; Goetz, W.; Heggy, E.; Pack, A.; Markiewicz, W.J.

    2012-01-01

    A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly hydrothermal activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5-2. km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. [1993]. Icarus 104, 301-323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma-water interaction or, alternatively, volatile-rich magmas early in the volcano's history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation.The findings point to a site of extensive volcanic and hydrologic activity with possibly a period of magma-water interaction and hydrothermal activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures. ?? 2011 Elsevier Inc..

  19. Searching for evidence of hydrothermal activity at Apollinaris Mons, Mars

    USGS Publications Warehouse

    El Maarry, M. Ramy; Dohm, James M.; Marzo, Giuseppe A.; Fergason, Robin; Goetz, Walter; Heggy, Essam; Pack, Andreas; Markiewicz, Wojciech J.

    2012-01-01

    A multidisciplinary approach involving various remote sensing instruments is used to investigate Apollinaris Mons, a prominent volcano on Mars, as well as the surrounding plains for signs of prolonged hydrologic and volcanic, and possibly hydrothermal activity. The main findings include (1) evidence from laser altimetry indicating the large thickness (1.5–2 km at some locations) of the fan deposits draping the southern flank contrary to previous estimates, coupled with possible layering which point to a significant emplacement phase at Apollinaris Mons, (2) corroboration of Robinson et al. (Robinson, M.S., Mouginis-Mark, P.J., Zimbelman, J.R., Wu, S.S.C., Ablin, K.K., Howington-Kraus, A.E. [1993]. Icarus 104, 301–323) hypothesis regarding the formation of incised valleys on the western flanks by density current erosion which would indicate magma–water interaction or, alternatively, volatile-rich magmas early in the volcano’s history, (3) mounds of diverse geometric shapes, many of which display summit depressions and occur among faults and fractures, possibly marking venting, (4) strong indicators on the flanks of the volcano for lahar events, and possibly, a caldera lake, (5) ubiquitous presence of impact craters displaying fluidized ejecta in both shield-forming (flank and caldera) materials and materials that surround the volcano that are indicative of water-rich target materials at the time of impact, (6) long-term complex association in time among shield-forming materials and Medusae Fossae Formation. The findings point to a site of extensive volcanic and hydrologic activity with possibly a period of magma–water interaction and hydrothermal activity. Finally, we propose that the mound structures around Apollinaris should be prime targets for further in situ exploration and search for possible exobiological signatures.

  20. Tuning optical properties of poly(3-hexylthiophene) nanoparticles through hydrothermal processing

    PubMed Central

    Lee, Seok Ho; Lee, Yong Baek; Park, Dong Hyuk; Kim, Mi Suk; Cho, Eun Hei; Joo, Jinsoo

    2011-01-01

    Poly(3-hexylthiophene) (P3HT) nanoparticles (NPs) were prepared by a reprecipitation method. Hydrothermal processing applied external pressure to the pristine P3HT NPs at temperatures ranging from 60 to 150 °C. Optical absorption and photoluminescence (PL) spectra for the hydrothermally treated P3HT NPs varied markedly with the processing temperature. With increasing treatment temperature, the absorption peak broadened and the peak position shifted from 510 to 623 nm; moreover, the intensity ratio of the 0–1 to 0–0 emission varied. These changes were caused by interactions between the P3HT main chains and alkyl side groups and conformational modifications induced by the high pressure during the hydrothermal process. The evolution of the optical absorption spectra of the P3HT NPs during the hydrothermal processing was strongly correlated with the variation of PL excitation spectra and with the PL emission spectra of a single NP. PMID:27877384

  1. Serpentinization-assisted deformation processes and characterization of hydrothermal fluxes at mid-ocean ridges

    NASA Astrophysics Data System (ADS)

    Genc, Gence

    Seafloor hydrothermal systems play a significantly important role in Earth’s energy and geochemical budgets and support the existence and development of complex biological ecosystems by providing nutrient and energy to microbial and macrafaunal ecosystems through geochemical fluxes. Heat output and fluid flow are key parameters which characterize hydrothermal systems at oceanic spreading centers by constraining models of hydrothermal circulation. Although integrated measurements of heat flux in plumes are critically important as well, quantification of heat flux at discrete sources (vent orifices versus patches of seafloor shimmering diffuse flow) from direct measurements is particularly essential for examining the partitioning of heat flow into focused and diffuse components of venting and determining geochemical fluxes from these two modes of flow. Hydrothermal heat output also constrains the permeability of young oceanic crust and thickness of the conductive boundary layer that separates magmatic heat source from overlying hydrothermal circulation. This dissertation will be fundamentally focused on three main inter-connected topics: (1) the design and development of direct high- or low-temperature heat flow measuring devices for hydrothermal systems, (2) the collection of new heat output results on four cruises between 2008 and 2010 at several distinct hydrothermal sites along mid-ocean ridges (MORs) to estimate total heat output from individual vent structures such as Dante, Hulk or the whole vent field (e.g., Main Endeavour Vent Field (MEF)), the partitioning between focused and diffuse hydrothermal venting in MEF, and determination of initial estimates of geochemical flux from diffuse hydrothermal fluids which may be influenced by the activity in subsurface biosphere and finally (3) the deformation and uplift associated with serpentinization at MORs and subduction zones. Despite extensive efforts spent for the last couple of decades on heat flow measurement

  2. Ammonium sulfide-assisted hydrothermal activation of palygorskite for enhanced adsorption of methyl violet.

    PubMed

    Tian, Guangyan; Wang, Wenbo; Kang, Yuru; Wang, Aiqin

    2016-03-01

    Herein, palygorskite (PAL) was activated via a simple hydrothermal process in the presence of ammonium sulfide, and the effects of activation on the microstructure, physico-chemical feature and adsorption behaviors of PAL were intensively investigated. The hydrothermal process evidently improved the dispersion of PAL crystal bundles, increased surface negative charges and built more active -Si-O(-) groups served as the new "adsorption sites". The adsorption property of the activated PAL for Methyl Violet (MV) was systematically investigated by optimizing the adsorption variables, including pH, ionic strength, contact time and initial MV concentration. The activated PAL exhibited a superior adsorption capability to the raw PAL for the removal of MV (from 156.05 to 218.11mg/g). The kinetics for MV adsorption followed pseudo second-order kinetic models, while the isotherm and thermodynamics results showed that the adsorption pattern well followed the Langmuir model. The structure analysis of PAL before and after adsorption demonstrated that electrostatic interaction and chemical association of -X-O(-) are the prominent driving forces for the adsorption process.

  3. Nanohydroxyapatite coating on a titanium-niobium alloy by a hydrothermal process.

    PubMed

    Xiong, Jianyu; Li, Yuncang; Hodgson, Peter D; Wen, Cui'e

    2010-04-01

    A novel one-step hydrothermal coating process was used to produce nanohydroxyapatite (nano-HA) coating on a titanium-niobium (TiNb) alloy substrate in a newly designed solution containing calcium and phosphate ions. The morphology of the coating was studied using scanning electron microscopy. The phase identification of the coating was carried out using X-ray diffraction, attenuated total reflectance Fourier transform infrared spectroscopy and transmission electron microscopy. The reaction between the surface of TiNb alloy and the solution during the hydrothermal process was studied by X-ray photoelectron spectroscopy. Results show that the coating formed on the surface of TiNb alloy was composed of nano-HA particles. During the hydrothermal process, TiO(2) and Nb(2)O(5) formed on the TiNb alloy surface and hydrated to Ti(OH)(4) and Nb(OH)(5), respectively. Calcium phosphate nucleated and grew into a layer of nano-HA particles on the surface of TiNb alloy under the hydrothermal conditions. The crystallinity of the nano-HA coating was improved with the increase in hydrothermal treatment temperature and time duration. Nano-HA coating with good crystallinity was produced on the TiNb alloy via the hydrothermal process at a temperature of 200 degrees C for 12 h.

  4. Lessons from studies of impact crater hydrothermal processes in terrestrial analogs and their implications for impact craters on Mars

    NASA Astrophysics Data System (ADS)

    Newsom, H. E.

    2011-12-01

    Studying hydrothermal processes in terrestrial impact craters as martian analogs has sometimes been fraught with objections, including the Earth's greater abundance of water, the neutral instead of acidic aqueous environments and the composition of the targets. Although recent discoveries have dispelled many objections, some misconceptions remain. For example, the relevance of the Chicxulub crater as a martian analog is sometimes questioned because the target was covered with sediments, including carbonates and sulfates. However the impactites at the Yaxcopoil-1 drill site are derived from the underlying silicate basement. Comparisons can also be difficult because of scale issues, as many terrestrial craters with evidence of hydrothermal activity, e.g. Lonar, Haughton, Ries etc., are smaller than the Martian craters with phyllosilicate signatures (Ehlmann et al., 2010). Summarizing, the results of many studies of terrestrial craters show that: 1) Most terrestrial craters larger than 1.8 km diameter have at least some evidence of aqueous or hydrothermal processes in the form of alteration minerals (e.g., Naumov, 2005). 2) Impact melts in crater fill and ejecta blankets provide heat that can produce hydrothermal alteration if water is available (Newsom, 1980). 3) The uplifted geothermal gradient can be as important a heat source as shock effects. 4) Mineralogical evidence for high-temperature fluids (> 350 oC) is present in the central uplift of the Manson structure, and in the ejecta from the Chicxulub impact, where precipitation of phyllosilicates from hydrothermal fluids has also been described (Newsom et al., 2010). 5) Impact deposits begin hot, but have an extended cooling period during which alteration phases can back react to low temperature phases with corresponding stable isotope signatures. 5) Hydrothermal fluids can travel long distances from their sources (e.g., Chicxulub, Yaxcopoil site) and are often localized to faults or porous breccias (e.g. Sudbury

  5. Diversity of hydrothermal processes and different types of epithermal deposits

    NASA Astrophysics Data System (ADS)

    Sidorov, A. A.; Volkov, A. V.

    2016-05-01

    It is shown that classical epithermal deposits with hydrothermal explosions, brecciated and framework-lamellar (including agate-like) structures, and well-developed bonanzas are usually pre-porphyry in origin. This inference seems to be important for development of the genetic model of a porphyry-epithermal ore-forming system as well as for exploration of gold-silver deposits and assessment of their potential.

  6. 30,000 years of hydrothermal activity at the lost city vent field.

    PubMed

    Früh-Green, Gretchen L; Kelley, Deborah S; Bernasconi, Stefano M; Karson, Jeffrey A; Ludwig, Kristin A; Butterfield, David A; Boschi, Chiara; Proskurowski, Giora

    2003-07-25

    Strontium, carbon, and oxygen isotope data and radiocarbon ages document at least 30,000 years of hydrothermal activity driven by serpentinization reactions at Lost City. Serpentinization beneath this off-axis field is estimated to occur at a minimum rate of 1.2 x 10(-4) cubic kilometers per year. The access of seawater to relatively cool, fresh peridotite, coupled with faulting, volumetric expansion, and mass wasting processes, are crucial to sustain such systems. The amount of heat produced by serpentinization of peridotite massifs, typical of slow and ultraslow spreading environments, has the potential to drive Lost City-type systems for hundreds of thousands, possibly millions, of years.

  7. Modelling GAC adsorption of biologically pre-treated process water from hydrothermal carbonization.

    PubMed

    Fettig, J; Liebe, H

    2015-01-01

    Granular-activated carbon (GAC) adsorption of biologically pre-treated process waters from hydrothermal carbonization (HTC) of different materials was investigated. Overall, isotherms showed that most of the dissolved organic substances are strongly adsorbable while the non-adsorbable fractions are small. The equilibrium data were modelled by using five fictive components to represent the organic matter. Mean film transfer coefficients and mean intraparticle diffusivities were derived from short-column and batch kinetic test data, respectively. Breakthrough curves in GAC columns could be predicted satisfactorily by applying the film-homogeneous diffusion model and using the equilibrium and kinetic parameters determined from batch tests. Thus, the approach is suited to model GAC adsorption of HTC process water under technical-scale conditions.

  8. A detailed kinetic model for the hydrothermal decomposition process of sewage sludge.

    PubMed

    Yin, Fengjun; Chen, Hongzhen; Xu, Guihua; Wang, Guangwei; Xu, Yuanjian

    2015-12-01

    A detailed kinetic model for the hydrothermal decomposition (HTD) of sewage sludge was developed based on an explicit reaction scheme considering exact intermediates including protein, saccharide, NH4(+)-N and acetic acid. The parameters were estimated by a series of kinetic data at a temperature range of 180-300°C. This modeling framework is capable of revealing stoichiometric relationships between different components by determining the conversion coefficients and identifying the reaction behaviors by determining rate constants and activation energies. The modeling work shows that protein and saccharide are the primary intermediates in the initial stage of HTD resulting from the fast reduction of biomass. The oxidation processes of macromolecular products to acetic acid are highly dependent on reaction temperature and dramatically restrained when temperature is below 220°C. Overall, this detailed model is meaningful for process simulation and kinetic analysis.

  9. Enhanced nanoscale catalyst precursor powders generated using a flow-through hydrothermal process

    SciTech Connect

    Darab, J.G.; Linehan, J.C.; Matson, D.W.

    1994-08-01

    A novel flow-through hydrothermal process, termed the Rapid Thermal Decomposition of precursors in Solution (RTDS), has been used to generate large quantities of ultra-fine, nano-crystalline hematite ({alpha}-Fe{sub 2}O{sub 3}), 6-line ferrihydrite (5Fe{sub 2}O{sub 3}{center_dot}9H{sub 2}O) and ferric oxyhydroxysulfate powders. The heterogeneous catalytic activity of these powders towards C-C bond scission in the model compound naphthyl bibenzylmethane and in the first-stage liquefaction of Blind Canyon seam coal was investigated. The effects of the crystalline phase and the agglomerate size of these powders on their catalytic activity are reported.

  10. Novel Psbnd O codoped g-C3N4 with large specific surface area: Hydrothermal synthesis assisted by dissolution-precipitation process and their visible light activity under anoxic conditions

    NASA Astrophysics Data System (ADS)

    Ma, Huiqiang; Li, Yang; Li, Shuang; Liu, Na

    2015-12-01

    Novel Psbnd O codoped g-C3N4 with large specific surface area is hydrothermal synthesized assisted by dissolution-precipitation process. The XRD, UV-vis, SEM and PL results indicate that the introduction of phosphorus and oxygen enhances the specific surface area of graphitic carbon nitride (from 12.8 to 92.5 m2 g-1), restrains the crystal growth, decreases the band gap energy (from 2.68 to 2.51 eV) and increases the separation efficiency of photogenerated electrons and holes, which increases the anoxic photocatalytic RhB degradation constants by approximately 27 times under visible light. Oxygen doping not only promotes the adsorption ability of reactant but also captures the photogenerated electrons to produce photogenerated holes for RhB degradation under anoxic condition. This study provides new insight into the design and fabrication of oxygen-free photocatalysts.

  11. Effects of hydrothermal alteration on Pb in the active PACMANUS hydrothermal field, ODP Leg 193, Manus Basin, Papua New Guinea: A LA-ICP-MS study

    NASA Astrophysics Data System (ADS)

    Beaudoin, Yannick; Scott, Steven D.; Gorton, Michael P.; Zajacz, Zoltan; Halter, Werner

    2007-09-01

    The conventional model of leaching volcanic rocks as a source of metals in a seafloor hydrothermal systems has been tested by examining the behavior of Pb and other trace elements during hydrothermal alteration. ODP Leg 193 drill sites 1188 (Snowcap) and 1189 (Roman Ruins) on Pual Ridge in the eastern Manus Basin offshore eastern Papua New Guinea provide a unique three-dimensional window into an active back-arc hydrothermal system. We investigate by means of a LA-ICP-MS microbeam technique the capacity of Pb to be leached from a host volcanic rock exposed to various types and intensities of alteration. Our results are in general agreement with previous studies that utilized bulk analytical techniques but provide a more detailed explanation of the processes. Fresh representative dacitic lavas from the Pual Ridge have an average whole rock Pb content of 5.2 ppm, an average interstitial glass Pb content of 5.6 ppm and an average plagioclase Pb content of 1.0 ppm. Altered matrix samples have highly variable Pb values ranging from 0 to 52.4 ppm. High Pb values in altered samples are associated with a low temperature chlorite and clay mineral assemblage, in some cases overprinted by a high temperature (up to 350 °C) silica-rich "bleaching" alteration. Only the most highly altered matrix samples have REE patterns that differ from the fresh Pual Ridge dacite. This may represent either different lava histories or alteration characteristics that have affected normally immobile REEs. Altered samples with the highest Pb values have similar REE patterns to those of the local unaltered lavas. They are compositionally similar to typical Pual Ridge dacites indicating a genetic relationship between the main regional volcanic suite and the subseafloor hydrothermally altered, Pb-enriched material. Relative loss/gain for Pb between the analyzed altered samples and a calculated precursor show a maximum relative gain of 901%. Samples with relative Pb gain from both drill sites are

  12. Characteristics of hydrothermal convection in inclined layers: implications for hydrothermal activity at slow-spreading axis.

    NASA Astrophysics Data System (ADS)

    Fontaine, F. J.; Cannat, M.; Escartin, J.; Dusunur, D.

    2006-12-01

    The thermal structure of segments along (slow-spreading) mid-ocean ridges is likely to be a key parameter controlling the distribution, dynamics and geometry of hydrothermal systems. It is usually considered that the depth of penetration of hydrothermal fluids at the ridge axis is a function of the depth to the brittle-ductile transition. At slow-spreading axis, it is likely that this depth varies both along- and across-axis, with a deepening of several kilometers from the segment center towards its ends [e.g., Hooft et al., 2000]. This geometry is a consequence of focused melt supply to the segment center, resulting in the episodic and localized injection of magma bodies in the crust, as observed at the Lucky Strike segment of the Mid-Atlantic ridge [Singh et al., 2005]. In order to study the effect of such slopes of the basal temperature on the dynamics of slow-spreading axis hydrothermal systems, we ran a series of two-dimensional numerical models of hydrothermal convection. As a first approximation and following previous studies [e.g., Rabinowicz et al., 1999], we assume that these systems can be represented as rectangular and inclined permeable layers. The models are single-phase and incorporate realistic fluid properties and permeabilities. We have explored the cases of slopes ranging from 0 to 15°, aspect ratios from 1 to 16, and permeabilities up to 10^{-14} m2. The basal slope controls the number of convective cells. As the slope increases, the ratio of the size of the downflow and upflow areas increases. Above a critical slope the circulation is uni-cellular and composed of a broad recharge zone and a focused discharge zone, and encompassing the whole length of the segment. We will present the implication of our models for the distribution of vent sites along slow-spreading ridge segments. The segment-scale circulation and focused outflow obtained could also explain the elevated heat flux at some of the main sites found along slow-spreading ridges like

  13. Hydrothermal mineralogy and fluid inclusions chemistry to understand the roots of active geothermal systems

    NASA Astrophysics Data System (ADS)

    Chambefort, I. S.; Dilles, J. H.; Heinrich, C.

    2013-12-01

    An integrated study to link magmatic textures, magmatic mineral compositions, hydrothermal alteration zoning, hydrothermal mineral chemistry, and fluid inclusion compositions has been undertaken to link an intrusive complex and its degassing alteration halo with their surface equivalent in an active geothermal system. Ngatamariki geothermal system, New Zealand, presents a unique feature in the Taupo Volcanic Zone (TVZ). Drilling intercepted an intrusive complex with a high temperature alteration halo similarly to what is observed in magmatic-derived ore deposits. Thus it presents the perfect opportunity to study the magmatic-hydrothermal transition of the TVZ by characterizing the nature of the deep magmatic fluids link to the heat source of the world known geothermal fields. The record of magmatic-hydrothermal fluid-rock interactions preserved at Ngatamariki may be analogous of processes presently occurring at depth beneath TVZ geothermal systems. The intrusive complex consists of over 5 km3 of tonalite, diorite, basalt and aplitic dykes. Evidence of undercooling subsolidus magmatic textures such as myrmekite and skeletal overgrowth are commonly observed and often linked to volatile loss. The fluids released during the crystallization of the intrusive complex are interpreted to be at the origin of the surrounding high temperature alteration halo. Advanced argillic to potassic alteration and high temperature acidic assemblage is associated with high-temperature quartz veining at depth and vuggy silica at the paleo-surface. Major element compositions of the white micas associated with the high temperature halo show a transition from, muscovite to phengite, muscovitic illite away from the intrusion, with a transition to pyrophyllite and/ or topaz, and andalusite characteristic of more acidic conditions. Abundant high-density (up to 59 wt% NaCl eq and homogenization temperatures of 550 degree Celsius and above) coexist with low-density vapor fluid inclusions. This

  14. Hydrothermal fluid-mineral interactions within volcanic sediment layer revealed by shallow drilling in active seafloor hydrothermal fields in the mid-Okinawa

    NASA Astrophysics Data System (ADS)

    Ishibashi, J.; Miyoshi, Y.; Tanaka, K.; Omori, E.; Takahashi, Y.; Furuzawa, Y.; Yamanaka, T.; Kawagucci, S.; Yoshizumi, R.; Urabe, T.

    2012-12-01

    TAIGA11 Expedition of R/V Hakurei-maru No.2 was conducted in June, 2011 to study subseafloor environment below active hydrothermal fields using a shallow drilling system (called as Benthic Multi-coring System, BMS). Three active hydrothermal fields at Iheya North Knoll (27 47'N, 126 54'E), at Izena Hole Jade site (27 16'N, 127 05'E) and at Izena Hole Hakurei site (27 15'N, 127 04'E) were selected as exploration targets, to focus on a hydrothermal fluid circulation system that develops in sediment consists of volcaniclastic and hemipelagic materials. In this presentation, we will report mineralogy of hydrothermal precipitates and altered clay minerals together with geochemistry of pore fluids, to discuss hydrothermal interactions beneath an active hydrothermal field. In the Iheya North Knoll hydrothermal field, the BMS drilling successfully attained to 453 cmbsf at the station 200 meters apart from the central mound area. The obtained core consisted almost entirely of grayish white altered mud that was identified as kaolinite by XRD. Pore fluid from the corresponding depth showed enrichment in major cations (Na, K, Ca and Mg) and Cl, which may be explained as a result of involvement of water into the kaolinite. Since kaolinite is considered as stable in rather acidic environment, its abundant occurrence beneath the seafloor would be attributed to a unique hydrothermal interaction. A possible scenario is intrusion of the vapor-rich hydrothermal component that has experienced phase separation. In the Jade hydrothermal fields in the Izena Hole, the BMS drilling successfully attained to 529 cmbsf at the marginal part of a hydrothermal field. The obtained core comprised grayish white hydrothermal altered mud below 370 cmbsf. Occurrence of native sulphur is also identified. Unfortunately, pore fluid could not be extracted from the intense alteration layer. In the Hakurei hydrothermal fields in the Izena Hole, the BMS drilling successfully attained to 610 cmbsf near one of

  15. Beryllium 10 in hydrothermal vent deposits from the East Pacific Ridges: Role of sediments in the hydrothermal processes

    SciTech Connect

    Valette-Silver, J.N.; Tera, F.; Klein, J.; Middleton, R.

    1987-10-10

    Beryllium 10 concentrations were determined for 31 handpicked hydrothermal sulfides, six oxyhydroxides, seven basalts, and five sediments collected from the hydrothermally active areas of the East Pacific ridges. The samples includes specimens from the East Pacific Rise (EPR) at 21 /sup 0/N and 13 /sup 0/N, the Galapagos Rift, the Guaymas Basin, and the Gorda and the Juan de Fuca ridges. Additional samples from massive sulfides associated with the Oman ophiolites were studied. In all samples, we obtained values ranging from 0.04 x 10/sup 6/ atoms/g to 125 x 10/sup 6/ atoms/g, with the lowest values being very close to our blank (0.015 x 10/sup 6/ atoms/g). The data show systematic variations with sample location and type. The /sup 10/Be concentrations measured for the mid-ocean basalts are of the order of 0.3 x 10/sup 6/ atoms/g and reach 3800 x 10/sup 6/ atoms/g for the pelagic deep-sea sediments collected near the EPR 21 /sup 0/N. Based on their /sup 10/Be concentrations, we can clearly distinguish two categories of sulfides: sulfides containing low /sup 10/Be concentration (<10 /sup 6/ atoms/g) sitting directly on the mid-ocean basalt (EPR of Juan de Fuca), and sulfides with high /sup 10/Be concentration (>10/sup 6/ atoms/g) located atop of a thick pile of young sediments (Guaymas Basin or Gorda Ridge).

  16. Ultramafic-hosted Hydrothermal Systems at Mid-Ocean Ridges: Serpentinization, Chloritization and Geochemical Controls on Mass-Transfer Processes

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E.; Pester, N. J.; Ding, K.

    2012-12-01

    Recent studies of seafloor hydrothermal systems associated with the slow spreading Mid-Atlantic Ridge have provided a wealth of information on the complex interplay between tectonic and magmatic processes that ultimately govern the chemical and physical evolution of these systems. The Lost City hydrothermal field (LCHF)(30°N) and the Rainbow hydrothermal system (36°N), for example, provide contrasting styles of heat and mass transfer that result in very different constraints on the composition of hydrothermal fluids. Hydrothermal fluids were sampled and analyzed during a series of ROV (Jason II) supported dives in 2008 to these and related vent sites along the northern MAR. In addition to deployment of conventional vent fluid sampling devices, in-situ chemical sensor systems were also used to better constrain pH and redox reactions. The general characteristics of the Lost City hydrothermal field, which is offset approximately 15km from the MAR owing to tectonic effects imposed by the emplacement of the Atlantis Massif, have been extensively reviewed in recent years. Vent fluids issuing from this peridotite-hosted system reveal temperatures of approximately 90-100°C, high concentrations of dissolved hydrogen and methane, and pH measured (25°C) values that exceed 10. The relatively low vent fluid temperatures notwithstanding, phase equilibria constraints imposed by dissolved Ca and sulfate suggest temperatures of approximately 200°C at depth, below the seafloor. New data for dissolved silica indicate a hydrothermal "root zone" lacking brucite, but where fluid chemistry and pH is buffered by serpentine-diopside-fluid equilibria. Consistent with previously published strontium and boron isotope measurements, data reported here for trace alkali elements (Cs, Rb, Li) indicate high fluid/rock mass ratios. Variably low dissolved Fe concentrations are broadly consistent with constraints imposed by magnetite-fluid equilibria at the high measured dissolved H2

  17. Post-Impact Hydrothermal Activity at the Haughton Impact Structure, Devon Island, Nunavut, Canada

    NASA Technical Reports Server (NTRS)

    Osinski, G. R.; Spray, J. G.; Bunch, T. E.; Grieve, R. A. F.; Schutt, J. W.; Lee, P.

    2000-01-01

    Evidence for impact-generated hydrothermal activity is reported from the Haughton crater, Canada. Two distinct settings have been found: (1) pipe structures with marcasite, pyrite and minor chalcopyrite; (2) cavity and fracture fillings with marcasite predominant.

  18. Impact-generated Hydrothermal Activity at the Chicxulub Crater

    NASA Astrophysics Data System (ADS)

    Kring, D. A.; Zurcher, L.; Abramov, O.

    2007-05-01

    Borehole samples recovered from PEMEX exploration boreholes and an ICDP scientific borehole indicate the Chicxulub impact event generated hydrothermal alteration throughout a large volume of the Maya Block beneath the crater floor and extending across the bulk of the ~180 km diameter crater. The first indications of hydrothermal alteration were observed in the crater discovery samples from the Yucatan-6 borehole and manifest itself in the form of anhydrite and quartz veins. Continuous core from the Yaxcopoil-1 borehole reveal a more complex and temporally extensive alteration sequence: following a brief period at high temperatures, impact- melt-bearing polymict breccias and a thin, underlying unit of impact melt were subjected to metasomatism, producing alkali feldspar, sphene, apatite, and magnetite. As the system continued to cool, smectite-series phyllosilicates appeared. A saline solution was involved. Stable isotopes suggest the fluid was dominated by a basinal brine created mostly from existing groundwater of the Yucatan Peninsula, although contributions from down-welling water also occurred in some parts of the system. Numerical modeling of the hydrothermal system suggests circulation occurred for 1.5 to 2.3 Myr, depending on the permeability of the system. Our understanding of the hydrothermal system, however, is still crude. Additional core recovery projects, particularly into the central melt sheet, are needed to better evaluate the extent and duration of hydrothermal alteration.

  19. Subaqueous cryptodome eruption, hydrothermal activity and related seafloor morphologies on the andesitic North Su volcano

    NASA Astrophysics Data System (ADS)

    Thal, Janis; Tivey, Maurice; Yoerger, Dana R.; Bach, Wolfgang

    2016-09-01

    North Su is a double-peaked active andesite submarine volcano located in the eastern Manus Basin of the Bismarck Sea that reaches a depth of 1154 m. It hosts a vigorous and varied hydrothermal system with black and white smoker vents along with several areas of diffuse venting and deposits of native sulfur. Geologic mapping based on ROV observations from 2006 and 2011 combined with morphologic features identified from repeated bathymetric surveys in 2002 and 2011 documents the emplacement of a volcanic cryptodome between 2006 and 2011. We use our observations and rock analyses to interpret an eruption scenario where highly viscous, crystal-rich andesitic magma erupted slowly into the water-saturated, gravel-dominated slope of North Su. An intense fragmentation process produced abundant blocky clasts of a heterogeneous magma (olivine crystals within a rhyolitic groundmass) that only rarely breached through the clastic cover onto the seafloor. Phreatic and phreatomagmatic explosions beneath the seafloor cause mixing of juvenile and pre-existing lithic clasts and produce a volcaniclastic deposit. This volcaniclastic deposit consists of blocky, non-altered clasts next, variably (1-100%) altered clasts, hydrothermal precipitates and crystal fragments. The usually applied parameters to identify juvenile subaqueous lava fragments, i.e. fluidal shape or chilled margin, were not applicable to distinguish between pre-existing non-altered clasts and juvenile clasts. This deposit is updomed during further injection of magma and mechanical disruption. Gas-propelled turbulent clast-recycling causes clasts to develop variably rounded shapes. An abundance of blocky clasts and the lack of clasts typical for the contact of liquid lava with water is interpreted to be the result of a cooled, high-viscosity, crystal-rich magma that failed as a brittle solid upon stress. The high viscosity allows the lava to form blocky and short lobes. The pervasive volcaniclastic cover on North Su is

  20. Hydrothermal processes in partially serpentinized peridotites from Costa Rica: evidence from native copper and complex sulfide assemblages

    NASA Astrophysics Data System (ADS)

    Schwarzenbach, Esther M.; Gazel, Esteban; Caddick, Mark J.

    2014-11-01

    Native metals and metal alloys are common in serpentinized ultramafic rocks, generally representing the redox and sulfur conditions during serpentinization. Variably serpentinized peridotites from the Santa Elena Ophiolite in Costa Rica contain an unusual assemblage of Cu-bearing sulfides and native copper. The opaque mineral assemblage consists of pentlandite, magnetite, awaruite, pyrrhotite, heazlewoodite, violarite, smythite and copper-bearing sulfides (Cu-pentlandite, sugakiite [Cu(Fe,Ni)8S8], samaniite [Cu2(Fe,Ni)7S8], chalcopyrite, chalcocite, bornite and cubanite), native copper and copper-iron-nickel alloys. Using detailed mineralogical examination, electron microprobe analyses, bulk rock major and trace element geochemistry, and thermodynamic calculations, we discuss two models to explain the formation of the Cu-bearing mineral assemblages: (1) they formed through desulfurization of primary sulfides due to highly reducing and sulfur-depleted conditions during serpentinization or (2) they formed through interaction with a Cu-bearing, higher temperature fluid (350-400 °C) postdating serpentinization, similar to processes in active high-temperature peridotite-hosted hydrothermal systems such as Rainbow and Logatchev. As mass balance calculations cannot entirely explain the extent of the native copper by desulfurization of primary sulfides, we propose that the native copper and Cu sulfides formed by local addition of a hydrothermal fluid that likely interacted with adjacent mafic sequences. We suggest that the peridotites today exposed on Santa Elena preserve the lower section of an ancient hydrothermal system, where conditions were highly reducing and water-rock ratios very low. Thus, the preserved mineral textures and assemblages give a unique insight into hydrothermal processes occurring at depth in peridotite-hosted hydrothermal systems.

  1. Role of tectonic and volcanic activity in hydrothermal systems at the southern Mariana Trough: detailed bathymetric characteristics of the hydrothermal sites

    NASA Astrophysics Data System (ADS)

    Yoshikawa, S.; Okino, K.; Asada, M.; Nogi, Y.; Mochizuki, N.; Nakamura, K.

    2012-12-01

    We present the detailed bathymetric characterization of field-scale geological features associated with hydrothermal systems in the southern Mariana Trough near 12°57'N, 143°37'E, using near-bottom swath mapping data collected by the autonomous underwater vehicle (AUV) Urashima during cruise YK09-08 and dive observation data acquired by the submersible Shinkai6500 during cruise YK10-11. In the study area, two of the hydrothermal sites are located on the active backarc spreading axis (the Snail and Yamanaka sites), one is located at the eastern foot of the axial high (the Archean site), and two are located on an off-axis knoll about 5 km from the spreading axis (the Pika and Urashima sites). We examined 1) the nature of' tectonic and volcanic controls on the hydrothermal systems, and 2) the relationship between geomorphological characteristics and hydrothermal activity based on the survey results (Yoshikawa et al., 2012). The two on-axis hydrothermal sites are possibly locally developed on a 4th order spreading segment, in association with diking events (on the basis of comparisons with previously studied cases on the East Pacific Rise). The three off-axis sites (the Archean, Urashima, and Pika sites) appear to represent locations of sustained hydrothermal activity that has created relatively large-scale hydrothermal features compared with those in the on-axis area. The formation of off-axis hydrothermal sites is likely to be closely related to an off-axis magma upwelling system, as evidenced by the absence of fault systems and the undeformed morphology of the mound and knoll. The three off-axis hydrothermal sites are composed mainly of breccia assemblages that probably originated from hydrothermal activity with black smoker venting. These areas are characterized by numerous ridge lines (height, mainly 1-6 m), conical mounds (height: < 100 m, diameter: < 300 m), and bumpy seabed. Most of the ridge lines have formed as a result of collapse of the seafloor. The

  2. Water under Hydrothermal, Supercritical, and High Pressure Conditions as Key to Developing Green Processes and New Technologies

    NASA Astrophysics Data System (ADS)

    Smith, Richard L.

    2010-11-01

    In this work, an overview of research and activity in the hydrothermal and supercritical fields is given. Properties and characteristics of water are reviewed in relation to separations, materials, and chemical conversion processes. Examples that are discussed include biomass fractionation, natural product extraction, material formation, biomass oxidation, biomass conversions, waste treatment, flames, and hydrocarbon upgrading. In the field of chromatography, water under hydrothermal conditions can be used to replace many organic solvents. As a solvent for separation processes, hot water can be used to achieve rapid and efficient fractionation of biomass or isolation of chemical compounds. In the field of materials, water in its supercritical state can be used to synthesize practical materials and to develop processes with low environmental burden. In the field of chemical processing, water can be used under oxidizing conditions to generate clean and renewable energy and to reduce the number of chemical steps for producing chemical products. A few other technological applications such as flames and hydrocarbon upgrading will be discussed. Water under hydrothermal, supercritical and high pressure conditions has many favorable properties that allow the development of green chemical processes and new technologies.

  3. Integral valorization of Leucaena diversifolia by hydrothermal and pulp processing.

    PubMed

    Feria, Manuel J; Alfaro, Ascensión; López, Francisco; Pérez, Antonio; García, Juan C; Rivera, Amanda

    2012-01-01

    Wood from the leguminous tree, Leucaena diversifolia, was subjected to hydrothermal treatment (autohydrolysis) at 160-180 °C for 0-30 min followed by ethanol-soda-anthraquinone delignification. The liquid phase contained 18.65 g of sugars per liter, and the solid phase had a gross heating value of 19.083 MJ/kg, but could also be used as a source of cellulose pulp for the production of paper with tear, burst, and tensile indexes of 2.4 N m2/kg, 2.6 MPa m2/kg and 40.7 kN m/kg, respectively. L. diversifolia lends itself readily to valorization for energy production, and also to integral, fractional exploitation by autohydrolysis and ethanol-soda-anthraquinone delignification, which can additionally bring environmental benefits to cropping zones.

  4. Removal of copper and cadmium from aqueous solution using switchgrass biochar produced via hydrothermal carbonization process.

    PubMed

    Regmi, Pusker; Garcia Moscoso, Jose Luis; Kumar, Sandeep; Cao, Xiaoyan; Mao, Jingdong; Schafran, Gary

    2012-10-30

    Biochar produced from switchgrass via hydrothermal carbonization (HTC) was used as a sorbent for the removal of copper and cadmium from aqueous solution. The cold activation process using KOH at room temperature was developed to enhance the porous structure and sorption properties of the HTC biochar. The sorption efficiency of HTC biochar and alkali activated HTC biochar (HTCB) for removing copper and cadmium from aqueous solution were compared with commercially available powdered activated carbon (PAC). The present batch adsorption study describes the effects of solution pH, biochar dose, and contact time on copper and cadmium removal efficiency from single metal ion aqueous solutions. The activated HTCB exhibited a higher adsorption potential for copper and cadmium than HTC biochar and PAC. Experiments conducted with an initial metal concentration of 40 mg/L at pH 5.0 and contact time of 24 h resulted in close to 100% copper and cadmium removal by activated HTCB at 2 g/L, far greater than what was observed for HTC biochar (16% and 5.6%) and PAC (4% and 7.7%). The adsorption capacities of activated HTCB for cadmium removal were 34 mg/g (0.313 mmol/g) and copper removal was 31 mg/g (0.503 mmol/g).

  5. Crystallization process of zircon and fergusonite during hydrothermal alteration in Nechalacho REE deposit, Thor Lake, Canada

    NASA Astrophysics Data System (ADS)

    Hoshino, M.; Watanabe, Y.; Murakami, H.; Kon, Y.; Tsunematsu, M.

    2012-04-01

    The core samples of two drill holes, which penetrate sub-horizontal mineralized horizons at Nechalacho REE deposit in the Proterozoic Thor Lake syenite, Canada, were studied in order to clarify magmatic and hydrothermal processes that enriched HFSE (e.g. Zr, Nb, Y and REE). Zircon is the most common REE minerals in Nechalacho REE deposit. The zircon is divided into five types as follows: Type-1 zircon occurs as single grain in phlogopite and the chondrite-normalized REE pattern is characterized by a steeply-rising slope from the LREE to the HREE with a positive Ce-anomaly and negative Eu-anomaly. This chemical characteristic is similar to that of igneous zircon. Type-2 zircon consists of HREE-rich magmatic porous core and LREE-Nb-F-rich hydrothermal rim. This type zircon is mostly included in phlogopite and fluorite, and occasionally in microcline. Type-3 zircon is characterized by euhedral to anhedral crystal, occurring in a complex intergrowth with REE fluorocarbonates. Type-3 zircons have high contents of REE, Nb and fluorine. Type-4 zircon consists of porous-core and -rim zones, but their chemical compositions are similar to each other. This type zircon is a subhedral crystal rimmed by fergusonite. Type-5 zircon is characterized by smaller, porous and subhedral to anhedral crystals. The interstices between small zircons are filled by fergusonite. Type-4 and -5 zircons show low REE and Nb contents. Occurrences of these five types of zircon are different according to the depth and degree of the alteration by hydrothermal solutions rich in F- and CO3 of the two drill holes, which permit a model for evolution of the zircon crystallization in Nechalacho REE deposit as follows: (1) type-1 (single magmatic zircon) is formed in miaskitic syenite. (2) LREE-Nb-F-rich hydrothermal zircon formed around HREE-rich magmatic zircon (type-2 zircon); (3) type-3 zircon crystallized thorough F and CO3-rich hydrothermal alteration of type-2 zircon which formed the complex

  6. Optimization of process condition of nanosilica production by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Qisti, N.; Indrasti, N. S.; Suprihatin

    2016-11-01

    Bagasse ashes have high silica content thus it can be used in nanosilicaproduction to increase its benefit value. This study aimed to get the best time for synthesis and to determine the optimum synthesis time and temperature. This study used the hydrothermal method, a simple method with relatively low reaction temperature and provide a good chemical homogeneity. Time varieties in synthesizing silica were 8,10 and 12 hours, at the temperature of 150 °C. But the results were not as expected. Moreover, optimization of synthesis temperature and time used 4 hours at the temperature of 150 °C based on previous studies. Optimization was conducted using the Response Surface Methodology (RSM). Later, a testusing PSA (Particle Size Analyzer) was performed to obtain particle sizes and PDI values (Polydispersity Index). The results showed that the prediction model of temperature synthesis was 152.67 °C synthesis time of 6 hours, particle size of 276.288 nm and PDI value of 0.189642. The tests showed that the size of particle obtained was 330.39 nm and PDI value at 0.3580. Actual results and predicted results were not significant different.

  7. Defining boundaries for the distribution of microbial communities beneath the sediment-buried, hydrothermally active seafloor.

    PubMed

    Yanagawa, Katsunori; Ijiri, Akira; Breuker, Anja; Sakai, Sanae; Miyoshi, Youko; Kawagucci, Shinsuke; Noguchi, Takuroh; Hirai, Miho; Schippers, Axel; Ishibashi, Jun-Ichiro; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

    2017-02-01

    Subseafloor microbes beneath active hydrothermal vents are thought to live near the upper temperature limit for life on Earth. We drilled and cored the Iheya North hydrothermal field in the Mid-Okinawa Trough, and examined the phylogenetic compositions and the products of metabolic functions of sub-vent microbial communities. We detected microbial cells, metabolic activities and molecular signatures only in the shallow sediments down to 15.8 m below the seafloor at a moderately distant drilling site from the active hydrothermal vents (450 m). At the drilling site, the profiles of methane and sulfate concentrations and the δ(13)C and δD isotopic compositions of methane suggested the laterally flowing hydrothermal fluids and the in situ microbial anaerobic methane oxidation. In situ measurements during the drilling constrain the current bottom temperature of the microbially habitable zone to ~45 °C. However, in the past, higher temperatures of 106-198 °C were possible at the depth, as estimated from geochemical thermometry on hydrothermally altered clay minerals. The 16S rRNA gene phylotypes found in the deepest habitable zone are related to those of thermophiles, although sequences typical of known hyperthermophilic microbes were absent from the entire core. Overall our results shed new light on the distribution and composition of the boundary microbial community close to the high-temperature limit for habitability in the subseafloor environment of a hydrothermal field.

  8. Hydrothermal activity at slow-spreading ridges: variability and importance of magmatic controls

    NASA Astrophysics Data System (ADS)

    Escartin, Javier

    2016-04-01

    Hydrothermal activity along mid-ocean ridge axes is ubiquitous, associated with mass, chemical, and heat exchanges between the deep lithosphere and the overlying envelopes, and sustaining chemiosynthetic ecosystems at the seafloor. Compared with hydrothermal fields at fast-spreading ridges, those at slow spreading ones show a large variability as their location and nature is controlled or influenced by several parameters that are inter-related: a) tectonic setting, ranging from 'volcanic systems' (along the rift valley floor, volcanic ridges, seamounts), to 'tectonic' ones (rift-bounding faults, oceanic detachment faults); b) the nature of the host rock, owing to compositional heterogeneity of slow-spreading lithosphere (basalt, gabbro, peridotite); c) the type of heat source (magmatic bodies at depth, hot lithosphere, serpentinization reactions); d) and the associated temperature of outflow fluids (high- vs.- low temperature venting and their relative proportion). A systematic review of the distribution and characteristics of hydrothermal fields along the slow-spreading Mid-Atlantic Ridge suggests that long-lived hydrothermal activity is concentrated either at oceanic detachment faults, or along volcanic segments with evidence of robust magma supply to the axis. A detailed study of the magmatically robust Lucky Strike segment suggests that all present and past hydrothermal activity is found at the center of the segment. The association of these fields to central volcanos, and the absence of indicators of hydrothermal activity along the remaining of the ridge segment, suggests that long-lived hydrothermal activity in these volcanic systems is maintained by the enhanced melt supply and the associated magma chamber(s) required to build these volcanic edifices. In this setting, hydrothermal outflow zones at the seafloor are systematically controlled by faults, indicating that hydrothermal fluids in the shallow crust exploit permeable fault zones to circulate. While

  9. Hydrothermal processing of cellulose: A comparison between oxidative and non-oxidative processes.

    PubMed

    Yousefifar, Azadeh; Baroutian, Saeid; Farid, Mohammed M; Gapes, Daniel J; Young, Brent R

    2017-02-01

    This study investigates oxidative and non-oxidative hydrothermal processing of cellulose at five different temperatures (180-260°C). Volatile fatty acids (VFAs) concentration, total suspended solid (TSS) degradation, dissolved organic carbon (DOC) and chemical oxygen demand (COD) were measured and compared in both processes. Moreover, the existence of hydrogen peroxide in both oxidative and non-oxidative processes was confirmed experimentally for the first time in literature. At temperatures ⩽220°C the amount of H2O2 produced in the oxidative process was higher (50 fold) than that of in the non-oxidative while at higher temperatures (⩾240°C) it was more for non-oxidative (3.5-5 fold). The concentration of VFAs in the non-oxidative process was lower than 10% of that in oxidative process. In both processes soluble COD increased with time and temperature, however at 260°C after reaching a maximum, it decreased with time due to conversion of some soluble intermediates to CO2 and water.

  10. Disseminated sulphides in basalts from the northern Central Indian Ridge: implications on late-stage hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Banerjee, Ranadip; Ray, Dwijesh

    2015-04-01

    This study examined the mineralogy and mineral chemistry of disseminated sulphides (mainly chalcopyrite-pyrite) in partly altered basalts from the northern Central Indian Ridge, Indian Ocean in order to understand the role of hydrothermal alterations and infer possible sulphide formation history. Pyrite and chalcopyrite are dominant sulphide minerals and generally associated with the oxide phases including magnetite and often ilmenite. Close association of sulphide and oxide minerals suggests that they are paragenetically related. Sulphides also occur as late impregnated veins cutting through the basaltic hosts. The chemical compositions of pyrite (avg. Fe 46.3 wt%, S 53.7 wt%) and chalcopyrite (avg. Cu 34.4 wt%, Fe 30.7 wt%, S 34.7 wt%) are almost uniform, while the secondary ilmenite often shows MnO enrichment (up to 3.0-3.4 wt%). The associated altered minerals typically resemble the greenschist facies mineral assemblages—e.g. chlorite±epidote. Evidence of albitisation and silicification suggests low-temperature hydrothermal alteration processes. This is supported by the bulk Au content (up to 60 ppb) of host-altered basalts with pyrite mineralisation. Au is usually associated with late-stage pyrites and thus related with low-temperature hydrothermal activity. Close to the dredge location, tectonic activity around the Vityaz megamullion might have promoted hydrothermal circulation and subsequent alteration of the mineral constituents in basalts, eventually inducing the formation of late-stage disseminated sulphide minerals in these rocks.

  11. A review on hydrothermal pre-treatment technologies and environmental profiles of algal biomass processing.

    PubMed

    Patel, Bhavish; Guo, Miao; Izadpanah, Arash; Shah, Nilay; Hellgardt, Klaus

    2016-01-01

    The need for efficient and clean biomass conversion technologies has propelled Hydrothermal (HT) processing as a promising treatment option for biofuel production. This manuscript discussed its application for pre-treatment of microalgae biomass to solid (biochar), liquid (biocrude and biodiesel) and gaseous (hydrogen and methane) products via Hydrothermal Carbonisation (HTC), Hydrothermal Liquefaction (HTL) and Supercritical Water Gasification (SCWG) as well as the utility of HT water as an extraction medium and HT Hydrotreatment (HDT) of algal biocrude. In addition, the Solar Energy Retained in Fuel (SERF) using HT technologies is calculated and compared with benchmark biofuel. Lastly, the Life Cycle Assessment (LCA) discusses the limitation of the current state of art as well as introduction to new potential input categories to obtain a detailed environmental profile.

  12. Improving Morphological Quality and Uniformity of Hydrothermally Grown ZnO Nanowires by Surface Activation of Catalyst Layer

    NASA Astrophysics Data System (ADS)

    Murillo, Gonzalo; Lozano, Helena; Cases-Utrera, Joana; Lee, Minbaek; Esteve, Jaume

    2017-01-01

    This paper presents a study about the dependence of the hydrothermal growth of ZnO nanowires (NWs) with the passivation level of the active surface of the Au catalyst layer. The hydrothermal method has many potential applications because of its low processing temperature, feasibility, and low cost. However, when a gold thin film is utilized as the seed material, the grown NWs often lack morphological homogeneity; their distribution is not uniform and the reproducibility of the growth is low. We hypothesize that the state or condition of the active surface of the Au catalyst layer has a critical effect on the uniformity of the NWs. Inspired by traditional electrochemistry experiments, in which Au electrodes are typically activated before the measurements, we demonstrate that such activation is a simple way to effectively assist and enhance NW growth. In addition, several cleaning processes are examined to find one that yields NWs with optimal quality, density, and vertical alignment. We find cyclic voltammetry measurements to be a reliable indicator of the seed-layer quality for subsequent NW growth. Therefore, we propose the use of this technique as a standard procedure prior to the hydrothermal synthesis of ZnO NWs to control the growth reproducibility and to allow high-yield wafer-level processing.

  13. Laboratory studies of a hydrothermal pretreatment process for municipal solid waste

    SciTech Connect

    Wallman, H.

    1995-04-06

    The objective of this work was to establish operating conditions for a hydrothermal pre-processing scheme for municipal solid wastes that produce a good slurry product for conversion in a Texaco gasifier. Work was carried out with model components such as wood, paper, and paper/plastic mixtures.

  14. Stabilization and separation of heavy metals in incineration fly ash during the hydrothermal treatment process.

    PubMed

    Hu, Yuyan; Zhang, Pengfei; Li, Jianping; Chen, Dezhen

    2015-12-15

    In the paper, hydrothermal treatment (HT) of MSWI fly ashes was performed to stabilize and separate heavy metals. Influences of pre-treatment, types of ferric and/or ferrous additives, and subsequent heavy metal stabilization procedure by adding phosphate were investigated. The chemical stability of hydrothermal products was examined by solid waste extraction procedure with acetic acid buffer solution. Mineralogical investigation of selected hydrothermal product was carried out by XRD. FEGE SEM- -EDX was used to study the morphology and surface compositions of the ash particles. Experimental results revealed that HT process facilitated heavy metal exposure to leaching solution. FEGE SEM-EDX images revealed that fly ash particles were re-organized during hydrothermal process and that the minerals with special shapes and containing high levels of heavy metals were formed. A mild acid washing treatment with final pH around 6.20 could remove soluble heavy metals. Therefore, it may be a proper pre- or post-treatment method for fly ash particles for the purpose of reducing heavy metal contents. For the purpose of stabilizing heavy metals, the addition of ferric/ferrous salts in the HT process or phosphate stabilization after HT is recommended. The HT process may be applied to realize the environmentally sound management of MSWI fly ash or to recover and utilize MSWI fly ash.

  15. Impact of hydrothermal process on the nutrient ingredients of restaurant garbage.

    PubMed

    Ren, Lian-hai; Nie, Yong-feng; Liu, Jian-guo; Jin, Yi-ying; Sun, Lu

    2006-01-01

    In order to recover the nutrient resource from restaurant garbage, a complete trial with 2 factors on 5 levels of experiments was carried out. The temperature and heating time are the main factors influencing on hydrothermal process (HP) by which improves the degradability and digestibility of the restaurant garbage favorably to make animal feeds or fertilizer. The results showed the variation of protein, saccharide, and oil in the garbage. It showed that protein dissolved and liquefied during hydrothermal process, which made organic nitrogen in solid phase transfer to liquid phase. After heating at 180 degrees C for 60 min, organic nitrogen in liquid phase began to transform into ammonia. It also showed that hydrothermal process could promote the dextrinization, dissolution of the starch and its hydrolysis to reducing sugar, due to that starch in the restaurant garbage decreases and reducing sugar increases. When the temperature reached 140 degrees C, the reducing sugar started to decrease due to chemical reactions. The cellulose was stable at 100--180cC. The floatable oil increased markedly in the hydrothermal process. The suitable condition for de-oil was observed at 160 degrees C heating for 80 min. Furthermore, the extraction of grease from the solid phase accords with first-order reaction dynamic model.

  16. Differentiating biotic from abiotic methane genesis in hydrothermally active planetary surfaces

    PubMed Central

    Oze, Christopher; Jones, L. Camille; Goldsmith, Jonas I.; Rosenbauer, Robert J.

    2012-01-01

    Molecular hydrogen (H2) is derived from the hydrothermal alteration of olivine-rich planetary crust. Abiotic and biotic processes consume H2 to produce methane (CH4); however, the extent of either process is unknown. Here, we assess the temporal dependence and limit of abiotic CH4 related to the presence and formation of mineral catalysts during olivine hydrolysis (i.e., serpentinization) at 200 °C and 0.03 gigapascal. Results indicate that the rate of CH4 production increases to a maximum value related to magnetite catalyzation. By identifying the dynamics of CH4 production, we kinetically model how the H2 to CH4 ratio may be used to assess the origin of CH4 in deep subsurface serpentinization systems on Earth and Mars. Based on our model and available field data, low H2/CH4 ratios (less than approximately 40) indicate that life is likely present and active. PMID:22679287

  17. Major off-axis hydrothermal activity on the northern Gorda Ridge

    USGS Publications Warehouse

    Rona, Peter A.; Denlinger, Roger P.; Fisk, M. R.; Howard, K. J.; Taghon, G. L.; Klitgord, Kim D.; McClain, James S.; McMurray, G. R.; Wiltshire, J. C.

    1990-01-01

    The first hydrothermal field on the northern Gorda Ridge, the Sea Cliff hydrothermal field, was discovered and geologic controls of hydrothermal activity in the rift valley were investigated on a dive series using the DSV Sea Cliff. The Sea Cliff hydrothermal field was discovered where predicted at the intersection of axis-oblique and axis-parallel faults at the south end of a linear ridge at mid-depth (2700 m) on the east wall. Preliminary mapping and smpling of the field reveal: a setting nested on nearly sediment-free fault blocks 300 m above the rift valley floor 2.6 km from the axis; a spectrum of venting types from seeps to black smokers; high conductive heat flow estimated to be equivalent to the convective flux of multiple black smokers through areas of the sea floor sealed by a caprock of elastic breccia primarily derived from basalt with siliceous cement and barite pore fillings; and a vent biota with Juan de Fuca Ridge affinites. These findings demonstrate the importance of off-axis hydrothermal activity and the role of the intersection of tectonic lineations in controlling hydrothermal sites at sea-floor spreading centers.

  18. Discovery of Active Hydrothermal Sites Along the Mariana Volcanic Arc, Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Baker, E. T.; Embley, R. W.; Resing, J. A.; Lupton, J. E.; Massoth, G. J.; de Ronde, C. E.; Nakamura, K.; Walker, S. L.

    2003-12-01

    Some 20,000 km of volcanic arcs, roughly one-third the total length of the global midocean ridge (MOR) system, rim the western Pacific Ocean. But compared to 25 years of hydrothermal investigations along MORs, exploration of similar activity on the estimated 600 submarine arc volcanoes is only beginning. In February 2003, as part of the Submarine Ring of Fire project funded by NOAA's Ocean Exploration Program, we made the first systematic survey of hydrothermal activity along the 1270-km-long Mariana intraoceanic volcanic arc, which lies almost entirely within the US EEZ. Prior fieldwork had documented active (but low-temperature) hydrothermal discharge on only three volcanoes: Kasuga 2, Kasuga 3, and Esmeralda Bank. During the cruise, we conducted 70 CTD operations over more than 50 individual volcanoes from 13° N to 23° N, plus a continuous CTD survey along 75 km of the back-arc spreading center (13° 15'N to 13° 41'N) adjacent to the southern end of the arc. We found evidence for active hydrothermal venting at 11 submarine volcanoes with summit (or caldera floor) depths ranging from 50 to 1550 m. Two additional sites were identified on the back-arc spreading center. Ongoing analyses of collected water samples could increase these totals. Our results confirmed continuing hydrothermal activity at Kasuga 2 (but not Kasuga 3) and Esmeralda Bank, in addition to newly discovered sites on nine other volcanoes. Many of these sites produce intense and widely dispersed plumes indicative of vigorous, high-temperature discharge. The volcanoes with active hydrothermal systems are about equally divided between those with and without summit calderas. The addition of the Marianas data greatly improves our view of hydrothermal sources along arcs. The 20,000 km of Pacific arcs can be divided between 6380 km of intraoceanic (i.e., mostly submarine) arcs and 13,880 km of island (i.e., mostly subaerial) arcs. At present, ˜15% of the total length of Pacific arcs has been surveyed

  19. Synthesis of magnetic nickel spinel ferrite nanospheres by a reverse emulsion-assisted hydrothermal process

    SciTech Connect

    Zhang Jilin; Shi Jianxin; Gong Menglian

    2009-08-15

    Nickel ferrite nanospheres were successfully synthesized by a reverse emulsion-assisted hydrothermal method. The reverse emulsion was composed of water, cetyltrimethyl ammonium bromide, polyoxyethylene(10)nonyl phenyl ether, iso-amyl alcohol and hexane. During the hydrothermal process, beta-FeO(OH) and Ni{sub 0.75}Fe{sub 0.25}(CO{sub 3}){sub 0.125}(OH){sub 2}.0.38H{sub 2}O (INCHH) nanorods formed first and then transformed into nickel spinel ferrite nanospheres. The phase transformation mechanism is proposed based on the results of X-ray powder diffraction, transmission electron microscopy and energy-dispersive X-ray spectroscopy, etc. Nickel ferrite may form at the end of the INCHH nanorods or from the solution accompanied by the dissolution of beta-FeO(OH) and INCHH nanorods. The X-ray photoelectron spectroscopy analysis shows that a few Fe{sup 3+} ions have been reduced to Fe{sup 2+} ions during the formation of nickel ferrite. The maximum magnetization of the nickel ferrite nanospheres obtained after hydrothermal reaction for 30 h is 55.01 emu/g, which is close to that of bulk NiFe{sub 2}O{sub 4}. - Graphical abstract: Nickel ferrite nanospheres were obtained through a reverse emulsion-assisted hydrothermal process. The phase transformation as a function of reaction time was studied based on the XRD, TEM and EDS analyses.

  20. Prospects for energy recovery during hydrothermal and biological processing of waste biomass.

    PubMed

    Gerber Van Doren, Léda; Posmanik, Roy; Bicalho, Felipe A; Tester, Jefferson W; Sills, Deborah L

    2017-02-01

    Thermochemical and biological processes represent promising technologies for converting wet biomasses, such as animal manure, organic waste, or algae, to energy. To convert biomass to energy and bio-chemicals in an economical manner, internal energy recovery should be maximized to reduce the use of external heat and power. In this study, two conversion pathways that couple hydrothermal liquefaction with anaerobic digestion or catalytic hydrothermal gasification were compared. Each of these platforms is followed by two alternative processes for gas utilization: 1) combined heat and power; and 2) combustion in a boiler. Pinch analysis was applied to integrate thermal streams among unit processes and improve the overall system efficiency. A techno-economic analysis was conducted to compare the feasibility of the four modeled scenarios under different market conditions. Our results show that a systems approach designed to recover internal heat and power can reduce external energy demands and increase the overall process sustainability.

  1. Application of the severity parameter for predicting viscosity during hydrothermal processing of dewatered sewage sludge for a commercial PFBC plant.

    PubMed

    Yanagida, Takashi; Fujimoto, Shinji; Minowa, Tomoaki

    2010-03-01

    Dewatered sewage sludge (approximately 80% water, but with low fluidity) was liquidized by hydrothermal treatment in order to make coal-water paste (CWP) for use in a pressurized-fluidized-bed-combustion (PFBC) power plant. Prediction of the viscosity of the dewatered sewage sludge during batch reactor hydrothermal liquefaction is important in order to avoid inputting excess energy. A single parameter, the severity parameter, has been used to predict viscosity during the hydrothermal process. The relationship between the viscosity of the slurry made from dewatered sewage sludge and the severity value was investigated. Viscosity reduction was associated with an increase in the severity value and was dependent on reaction temperature and time. It was concluded that predicting the viscosity of dewatered sewage sludge during the hydrothermal process by means of the severity parameter is possible. This method is expected to provide a useful guideline for choosing reaction conditions based on prediction of the viscosity of the sludge slurry during the hydrothermal process.

  2. Synthesis of pyrite FeS2 nanorods by simple hydrothermal method and its photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Morales-Gallardo, M. V.; Ayala, A. M.; Pal, Mou; Cortes Jacome, M. A.; Toledo Antonio, J. A.; Mathews, N. R.

    2016-09-01

    In this work, FeS2 nanorods were synthetized by hydrothermal method. The advantages of our process were the high yield, simplicity and reproducibility. The material was studied in detail using different experimental tools such as XRD, SEM, HRTEM, EDXS, XPS, Raman, and UV-vis reflectance. XRD pattern and Raman data revealed good crystalline quality for the as synthesized pyrite FeS2. SEM analysis displayed the rod-like morphologies of FeS2 which seemed to grow radially from a center giving a flower-like appearance. From TEM images the approximate length and diameter of nano-rods were determined as 275 and 15 nm respectively. The material showed excellent photocatalytic activity which was assessed from the degradation of the methlyene blue.

  3. Amino acids assisted hydrothermal synthesis of hierarchically structured ZnO with enhanced photocatalytic activities

    NASA Astrophysics Data System (ADS)

    Guo, Yanxia; Lin, Siwen; Li, Xuan; Liu, Yuping

    2016-10-01

    Novel hierarchically structured ZnO, including rose-like, dandelion-like and flower-like, have been synthesized through a simple hydrothermal process using different amino acids (glutamine, histidine and glycine) as structure-directing agents and urea as deposition agent, followed by subsequent calcination. Amino acids played a crucial role in the formation of hierarchically structured ZnO, and different amino acids could induce different exquisite shapes and assembly ways, as well as more oxygen defects. The prepared hierarchically structured ZnO exhibited excellent photocatalytic activities for the photodegradation of Rhodamine B, which was associated with their special hierarchical structures, large BET surface area and the existence of more oxygen defects. Amino acid-assisted growth mechanism of hierarchically structured ZnO was also discussed.

  4. Investigations on Bi{sub 25}FeO{sub 40} powders synthesized by hydrothermal and combustion-like processes

    SciTech Connect

    Köferstein, Roberto Buttlar, Toni; Ebbinghaus, Stefan G.

    2014-09-15

    The syntheses of phase-pure and stoichiometric iron sillenite (Bi{sub 25}FeO{sub 40}) powders by a hydrothermal (at ambient pressure) and a combustion-like process are described. Phase-pure samples were obtained in the hydrothermal reaction at 100 °C (1), whereas the combustion-like process leads to pure Bi{sub 25}FeO{sub 40} after calcination at 750 °C for 2 h (2a). The activation energy of the crystallite growth process of hydrothermally synthesized Bi{sub 25}FeO{sub 40} was calculated as 48(9) kJ mol{sup −1}. The peritectic point was determined as 797(1) °C. The optical band gaps of the samples are between 2.70(7) eV and 2.81(6) eV. Temperature and field-depending magnetization measurements (5−300 K) show a paramagnetic behaviour with a Curie constant of 55.66×10{sup −6} m{sup 3} K mol{sup −1} for sample 1 and C=57.82×10{sup −6} m{sup 3} K mol{sup −1} for sample 2a resulting in magnetic moments of µ{sub mag}=5.95(8) µ{sub B} mol{sup −1} and µ{sub mag}=6.07(4) µ{sub B} mol{sup −1}. The influence of amorphous iron-oxide as a result of non-stoichiometric Bi/Fe ratios in hydrothermal syntheses on the magnetic behaviour was additionally investigated. - Graphical abstract: Bi{sub 25}FeO{sub 40} powders were prepared by a hydrothermal method and a combustion process. The optical band gaps and the peritectic point were determined. The magnetic behaviour was investigated depending on the synthesis and the initial Bi/Fe ratios. The influence of amorphous iron-oxide on the magnetic properties was examined. - Highlights: • Two simple syntheses routes for stoichiometric Bi{sub 25}FeO{sub 40} powders using starch as polymerization agent. • Monitoring the phase evolution and crystallite growth kinetics during the syntheses. • Determination of the optical band gap and melting point. • Investigations of the magnetic behaviour of Bi{sub 25}FeO{sub 40} powders. • Influence of amorphous iron oxide and a non-stoichiometric Bi/Fe ratio on the

  5. Present-day submarine hydrothermal activity in the Taupo-Rotorua Zone (Bay of Plenty, New Zealand)

    SciTech Connect

    Osipenko, A.B.; Egorov, Yu.O.; Fazlullin, S.M.; Gavrilenko, G.M.; Shul`kin, V.I.; Chertkova, L.V.

    1994-09-01

    We made detailed descriptions of the structure and material composition of sedimentary and water columns in the vicinity of active submarine hydrothermal activity in the southern part of the Bay of Plenty (North Island, New Zealand). Geophysical methods revealed that the hydrothermal system is confined to a tectonically distinct zone with a sedimentary cover characterized by complex structure. Chemical and mineralogical investigations confirmed that the activity of underwater vents exerts no substantial regional influence on the composition and features of ore mineralization in these formations. It is shown that essentially hydrothermal formations distinguishable within areas of otherwise monotypic sediments directly coincide with zones of hydrothermal discharge in the ocean floor. The absence of pronounced hydrothermal anomalies, together with the presence of {open_quotes}tongues{close_quotes} of anomalous concentrations of water-soluble gases suggests that the discharges are primarily hydrothermal in character.

  6. Trace element behavior in hydrothermal experiments: Implications for fluid processes at shallow depths in subduction zones

    NASA Astrophysics Data System (ADS)

    You, C.-F.; Castillo, P. R.; Gieskes, J. M.; Chan, L. H.; Spivack, A. J.

    1996-05-01

    Chemical evaluation of fluids affected during progressive water-sediment interactions provides critical information regarding the role of slab dehydration and/or crustal recycling in subduction zones. To place some constraints on geochemical processes during sediment subduction, reactions between décollement sediments and synthetic NaCl-CaCl 2 solutions at 25-350°C and 800 bar were monitored in laboratory hydrothermal experiments using an autoclave apparatus. This is the first attempt in a single set of experiments to investigate the relative mobilities of many subduction zone volatiles and trace elements but, because of difficulties in conducting hydrothermal experiments on sediments at high P-T conditions, the experiments could only be designed for a shallow (˜ 10 km) depth. The experimental results demonstrate mobilization of volatiles (B and NH 4) and incompatible elements (As, Be, Cs, Li, Pb, Rb) in hydrothermal fluids at relatively low temperatures (˜ 300°C). In addition, a limited fractionation of light from heavy rare earth elements (REEs) occurs under hydrothermal conditions. On the other hand, the high field strength elements (HFSEs) Cr, Hf, Nb, Ta, Ti, and Zr are not mobile in the reacted fluids. The observed behavior of volatiles and trace elements in hydrothermal fluids is similar to the observed enrichment in As, B, Cs, Li, Pb, Rb, and light REEs and depletion in HFSEs in arc magmas relative to magmas derived directly from the upper mantle. Thus, our work suggests a link between relative mobilities of trace elements in hydrothermal fluids and deep arc magma generation in subduction zones. The experimental results are highly consistent with the proposal that the addition of subduction zone hydrous fluids to the subarc mantle, which has been depleted by previous melting events, can produce the unique characteristics of arc magmas. Moreover, the results suggest that deeply subducted sediments may no longer have the composition necessary to generate

  7. Characteristics of hydrothermal sedimentation process in the Yanchang Formation, south Ordos Basin, China: Evidence from element geochemistry

    NASA Astrophysics Data System (ADS)

    He, Cong; Ji, Liming; Wu, Yuandong; Su, Ao; Zhang, Mingzhen

    2016-11-01

    Hydrothermal sedimentation occurred in the Triassic Yanchang Formation, Ordos Basin, China. However, their macroscopic features at the scale of the stratum and hydrothermal sources still lack correlational research. This paper performed element geochemical study on a large number of core samples collected from the Yanchang Formation of a new drilling well located in the south Ordos Basin. The SiO2/(K2O + Na2O) vs. MnO/TiO2 crossplot and Fe vs. Mn vs. (Cu + Co + Ni) × 10 ternary diagram demonstrate that the Yanchang stratum in the study area has, in general, hydrothermal components. The Al/(Al + Fe + Mn) and (Fe + Mn)/Ti ratios of the core samples range from 0.34 to 0.84 and 4.81 to 50.54, averaging 0.66 and 10.67, respectively, indicating that the stratum is a set of atypical hydrothermal sedimentation with much terrigenous input. Data analysis shows that the hydrothermal source in the study area was from the deep North Qinling Orogen around the south margin of the basin, where some active tectonic and volcanic activities took place, rather than from the relatively stable internal basin. Early Indosinian movement and volcanic activities activated basement faults around the southern margin of the basin, providing vents for the deep hydrothermal fluid upwelling. The hydrothermal indicators suggest that the study area experienced 4 episodes of relatively stronger hydrothermal activity, namely during the Chang 10, Chang 9-1, Chang 7-3 and Chang 6-2 periods. We also propose a new hydrothermal sedimentation model of hydrothermal fluids overflowing from basin margin faults, for the Yanchang Formation, which is reported here for the first time.

  8. Catalytic Hydrothermal Gasification

    SciTech Connect

    Elliott, Douglas C.

    2015-05-31

    The term “hydrothermal” used here refers to the processing of biomass in water slurries at elevated temperature and pressure to facilitate the chemical conversion of the organic structures in biomass into useful fuels. The process is meant to provide a means for treating wet biomass materials without drying and to access ionic reaction conditions by maintaining a liquid water processing medium. Typical hydrothermal processing conditions are 523-647K of temperature and operating pressures from 4-22 MPa of pressure. The temperature is sufficient to initiate pyrolytic mechanisms in the biopolymers while the pressure is sufficient to maintain a liquid water processing phase. Hydrothermal gasification is accomplished at the upper end of the process temperature range. It can be considered an extension of the hydrothermal liquefaction mechanisms that begin at the lowest hydrothermal conditions with subsequent decomposition of biopolymer fragments formed in liquefaction to smaller molecules and eventually to gas. Typically, hydrothermal gasification requires an active catalyst to accomplish reasonable rates of gas formation from biomass.

  9. Production of monosaccharides from napier grass by hydrothermal process with phosphoric acid.

    PubMed

    Takata, Eri; Tsutsumi, Ken; Tsutsumi, Yuji; Tabata, Kenji

    2013-09-01

    The production of monosaccharides from napier grass was investigated in the presence of acid catalysts using the hydrothermal process. When the napier grass was treated with 3 wt.% phosphoric acid at 160°C for 15min, the xylose yield reached 10.3 wt.%, corresponding to 72.0% of the xylan in it, whereas glucose was hardly obtained. A combined process was then conducted using an 85 wt.% phosphoric acid treatment at 60 °C for 1h followed by a hydrothermal treatment with 3 wt.% phosphoric acid. In the initial treatment with concentrated phosphoric acid the most of xylan was hydrolyzed to xylose, and the crystalline cellulose was converted to its amorphous form. The hydrolysis of cellulose to glucose was significantly enhanced during the following hydrothermal process with 3 wt.% phosphoric acid at 200 °C for 8 min. Consequently, 77.2% yield of xylose and 50.0% yield of glucose were obtained from the combined process.

  10. Facile fabrication of superhydrophobic surfaces on wood substrates via a one-step hydrothermal process

    NASA Astrophysics Data System (ADS)

    Liu, Ming; Qing, Yan; Wu, Yiqiang; Liang, Jin; Luo, Sha

    2015-03-01

    Superhydrophobic nanocomposite surfaces were successfully fabricated on wood substrates via a one-step hydrothermal process. The morphology of the nanocomposite surfaces was characterized using scanning electron microscopy (SEM), and the elemental composition was determined via energy-dispersive X-ray spectrometry (EDS), X-ray diffraction (XRD) analysis, and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the crystallization of the anatase phase of TiO2 was prevented because of the presence of vinyltriethoxysilane [VTES, CH2CHSi(OC2H5)3] during the hydrothermal process. In addition, the nanocomposite contained Ti/Si particles with diameters ranging from 50 to 100 nm that thoroughly covered the wood substrate. Furthermore, the roughness coupled with the presence of low surface free energy groups led to superhydrophobicity; the static water contact angle (WCA) was as high as 153°, and the sliding angle was very low.

  11. Microwave-hydrothermal process for the synthesis of rutile

    SciTech Connect

    Baldassari, Sara; Komarneni, Sridhar . E-mail: komarneni@psu.edu; Mariani, Emilia; Villa, Carla

    2005-11-03

    The synthesis of pure rutile titanium dioxide is not an easy achievement, as the crystallization process generally leads to mixtures of two or even three phases; moreover the synthetic processes normally used by industry require harsh reaction conditions. We carried out the synthesis of titanium dioxide from an aqueous titanium tetrachloride solution under microwave irradiation in the reaction time range of 5-120 min. We mostly obtained mixtures of rutile and anatase, but obtained single-phase rutile after a 2-h treatment at 160 deg. C; transmission electron micrographs revealed well-dispersed spherical nanoparticles. We also investigated the effects of dilution and addition of a dispersant (polyvinylpyrrolidone) on phase crystallization and particle shape.

  12. Cavitational Hydrothermal Oxidation: A New Remediation Process - Final Report

    SciTech Connect

    Suslick, K. S.

    2001-07-05

    During the past year, we have continued to make substantial scientific progress on our understanding of cavitation phenomena in aqueous media and applications of cavitation to remediation processes. Our efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions.

  13. Hydrogeological and geochemical modeling of hydrothermal fluids circulation in active ultramafic-hosted systems under CAST3M

    NASA Astrophysics Data System (ADS)

    Perez, F.; Mugler, C.; Jean-Baptiste, P.; Charlou, J. L.; Donval, J.; Vidal, O.; Marcailloux, C.; Munoz, M.

    2010-12-01

    Hydrothermal circulation at mid-ocean ridges is a fundamental process that impacts the transfer of energy and water from the interior of the Earth to the Crust, Hydrosphere and biosphere. Along the Mid-Atlantic Ridge (MAR), at precisely located ultramafic-hosted systems, important fluxes of heat, hydrogen and Iron are observed (Charlou et al., 2010 AGU Monograph series). It is now demonstrated that high and low-temperature hydrothermal activity and mantle degassing are indicators of ongoing serpentinization process. For a real understanding of this process and to estimate heat and hydrogen fluxes, numerical modeling leant on field data and laboratory experiments can yield results of interest. We thus developed a thermo-hydrogeological numerical model using a Finite Volume method to simulate heat driven fluid flows in geological layers, encoded under CAST3M, and presented here. For homogeneous medias, we successfully obtained exiting fluid temperatures that natural hydrothermal fluids usually reach. Considering laboratory experiments, we coupled, under CAST3M, our thermo-hydrogeological model to a geochemical model of serpentinization reaction. This last model is based on a reaction front velocity model calibrated by laboratory experiments. Primary results are presented here.

  14. ESR dating of submarine hydrothermal activities using barite in sulfide deposition

    NASA Astrophysics Data System (ADS)

    Toyoda, S.; Fujiwara, T.; Ishibashi, J.; Isono, Y.; Uchida, A.; Takamasa, A.; Nakai, S.

    2012-12-01

    The temporal change of submarine hydrothermal activities has been an important issue in the aspect of the evolution of hydrothermal systems which is related with ore formation (Urabe, 1995) and biological systems sustained by the chemical species arising from hydrothermal activities (Macdonald et al., 1980). Determining the ages of the hydrothermal deposit will provide essential information on such studies. Dating methods using disequilibrium between radioisotopes such as U-Th method (e.g. You and Bickle, 1998), 226}Ra-{210Pb and 228}Ra-{228Th method (e.g. Noguchi et al., 2011) have been applied to date submarine hydrothermal deposits. ESR (electron spin resonance) dating method is commonly applied to fossil teeth, shells, and quartz of Quaternay period where the natural accumulated dose is obtained from the intensities of the ESR signals which are created by natural radiation. The natural dose is divided by the dose rate to the mineral/sample to deduce the age. Okumura et al., (2010) made the first practical application of ESR (electron spin resonance) dating technique to a sample of submarine hydrothermal barite (BaSO4) to obtain preliminary ages, where Kasuya et al. (1991) first pointed out that barite can be used for ESR dating. Knowing that ESR dating of barite is promising, in this paper, we will present how we have investigated each factor that contributes ESR dating of barite in submarine hydrothermal sulfide deposition. (1) The best ESR condition for measuring the SO3- signal in barite is with the microwave power of 1mW and modulation amplitude of 0.1mT. (2) As results of heating experiments, the signal was found to be stable for the dating age range of several thousands. (3) 226Ra replacing Ba in barite is the source of the radiation. The amount of radioactive elements in sulfide mineral surrounding barite is negligible. (4) The external radiation from the sea water is negligible even in the submarine hydrothermal area where the radiation level is much

  15. Silica nanoparticles as indicator of hydrothermal activities at Enceladus ocean floor

    NASA Astrophysics Data System (ADS)

    Postberg, F.; Hsu, S.; Sekine, Y.; Kempf, S.; Juhasz, A.; Horanyi, M.; Moragas-Klostermeyer, G.; Srama, R.

    2013-12-01

    Silica nanoparticles as indicator of hydrothermal activities at Enceladus ocean floor F. Postberg, H.-W. Hsu, Y. Sekine, S. Kempf, A. Juhasz, M. Horanyi, G. Moragas-Klostermeyer, R. Srama Silica serves as a unique indicator of hydrothermal activities on Earth as well as on Mars. Here we report the Cassini Cosmic Dust Analyser (CDA) observation of nanosilica particles from the Saturnian system. Based on their interaction with the solar wind electromagnetic fields, these charged nanosilica particles, so-called stream particles, are found to be originated in Saturn's E ring, indicating Enceladus being their ultimate source. CDA stream particle mass spectra reveal a metal-free but silicon-rich composition that is only plausible for nearly pure silica particles. The size range derived from our measurements confines the size of these particles to a radius of 2 - 8 nm. The unique properties of nano-grains with the observed composition and size are a well-known phenomenon on Earth and their formation requires specific hydrothermal rock-water interactions. The observation of Saturnian nanosilica particles thus serves as an evidence of hydrothermal activities at the interface of Enceladus subsurface ocean and its rocky core. Considering plasma erosion as the major mechanism of releasing embedded nanosilica particles from their carriers, the much larger E ring ice grains, our dynamical model and CDA observation provide a lower limit on the average nanosilica concentration in E ring grains. Together with dedicated hydrothermal experiments (Sekine at al., 2013) this can be translated into constraints on the hydrothermal activities on Enceladus. Measurements and experiments both point at dissolved silica concentrations at the ocean floor in the order of 1 - 3 mMol. The hydrothermal reactions likely take place with a pristine, chondritic rock composition at temperature higher than 130°C (Sekine at al. 2013). Colloidal nano-silica forms upon supersaturation during cooling of the

  16. Acid-base behavior in hydrothermal processing of wastes. 1997 annual progress report

    SciTech Connect

    1997-01-01

    'A major obstacle to the development of hydrothermal technology for treating DOE wastes has been a lack of scientific knowledge of solution chemistry, thermodynamics and transport phenomena. The progress over the last year is highlighted in the following four abstracts from manuscripts which have been submitted to journals. The authors also have made considerable progress on a spectroscopic study of the acid-base equilibria of Cr(VI). They have utilized novel spectroscopic indicators to study acid-base equilibria up to 380 C. Until now, very few systems have been studied at such high temperatures, although this information is vital for hydrothermal processing of wastes. The pH values of aqueous solutions of boric acid and KOH were measured with the optical indicator 2-naphthol at temperatures from 300 to 380 C. The equilibrium constant Kb-l for the reaction B(OH)3 + OH{sup -} = B(OH){sup -4} was determined from the pH measurements and correlated with a modified Born model. The titration curve for the addition of HCl to sodium borate exhibits strong acid-strong base behavior even at 350 C and 24.1 MPa. At these conditions, aqueous solutions of sodium borate buffer the pH at 9.6 t 0.25. submitted to Ind. Eng. Chem. Res. Acetic Acid and HCl Acid-base titrations for the KOH-acetic acid or NH{sub 3} -acetic acid systems were monitored with the optical indicator 2-naphthoic acid at 350 C and 34 MPa, and those for the HCl;Cl- system with acridine at 380 C and up to 34 MPa (5,000 psia ). KOH remains a much stronger base than NH,OH at high temperature. From 298 K to the critical temperature of water, the dissociation constant for HCl decreases by 13 orders of magnitude, and thus, the basicity of Cl{sup -} becomes significant. Consequently, the addition of NaCl to HCl raises the pH. The pH titration curves may be predicted with reasonable accuracy from the relevant equilibrium constants and Pitzer''s formulation of the Debye- Htickel equation for the activity coefficients.'

  17. Assessing microbial processes in deep-sea hydrothermal systems by incubation at in situ temperature and pressure

    NASA Astrophysics Data System (ADS)

    McNichol, Jesse; Sylva, Sean P.; Thomas, François; Taylor, Craig D.; Sievert, Stefan M.; Seewald, Jeffrey S.

    2016-09-01

    At deep-sea hydrothermal vents, a large source of potential chemical energy is created when reducing vent fluid and oxidizing seawater mix. In this environment, chemolithoautotrophic microbes catalyze exergonic redox reactions which in turn provide the energy needed to fuel their growth and the fixation of CO2 into biomass. In addition to producing new organic matter, this process also consumes compounds contained both in vent fluid and entrained seawater (e.g. H2, NO3-). Despite their biogeochemical importance, such reactions have remained difficult to quantify due to methodological limitations. To address this knowledge gap, this study reports a novel application of isobaric gas-tight fluid samplers for conducting incubations of hydrothermal vent fluids at in situ temperature and pressure. Eighteen 24 h incubations were carried out, representing seven distinct conditions that examine amendments consisting of different electron donors and acceptors. Microbial activity was observed in all treatments, and time series chemical measurements showed that activity was limited by electron acceptor supply, confirming predictions based on geochemical data. Also consistent with these predictions, the presence of nitrate increased rates of hydrogen consumption and yielded ammonium as a product of nitrate respiration. The stoichiometry of predicted redox reactions was also determined, revealing that the sulfur and nitrogen cycles are incompletely understood at deep-sea vents, and likely involve unknown intermediate redox species. Finally, the measured rates of redox processes were either equal to or far greater than what has been reported in previous studies where in situ conditions were not maintained. In addition to providing insights into deep-sea hydrothermal vent biogeochemistry, the methods described herein also offer a practical approach for the incubation of any deep-sea pelagic sample under in situ conditions.

  18. Exploring an active hydrothermal system - An analogue study from the Swiss Alps

    NASA Astrophysics Data System (ADS)

    Egli, Daniel; Herwegh, Marco; Berger, Alfons; Baron, Ludovic

    2016-04-01

    Understanding the detailed flow paths in hydrothermal reservoirs is crucial for successful exploration of naturally porous and permeable rock masses for energy production. However, due to the common inaccessibility of active hydrothermal systems of suitable depth, e.g. in the northern Alpine foreland of the European Alps, direct observations are normally impossible and the knowledge about such systems is still insufficient. For that reason, a known fault-bound hydrothermal system in the crystalline basement of the Aar Massif serves as an analogue for potential geothermal reservoirs in the deep crystalline subsurface of the northern Alpine foreland. During summer 2015, a 125 m hole has been drilled across this active hydrothermal zone on the Grimsel Pass for in-situ characterization of its structural, petrophysical, mechanical as well as geophysical parameters. With this information, this project aims at improving the knowledge of natural hydrothermal systems as a potentially exploitable energy source. The investigated system is characterized by a central breccia zone surrounded by different types of cataclasites and localized high strain zones. The surrounding includes different altered and deformed granitoid host rocks. In this study, we focus on the ductile and brittle deformation (shear zones, fractures, joints) that provides the main fluid pathways. Their spatial distribution around a central water-bearing breccia zone as well as their continuity and permeability provide constraints on the water flow paths in such structurally controlled hydrothermal systems. The aim will be the connection of detailed structural data with petrophysical parameters such as porosities and permeabilities. The drillcore shows the high variability of deformation structures and related fluid pathways at different scales (millimeter-decameter) demonstrating the urgent need for an improved understanding of the link between mechanical evolution, associated deformation structures as well

  19. Hydrothermal carbonization of biomass residuals: A comparative review of the chemistry, processes and applications of wet and dry pyrolysis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper reviews chemistry, processes and application of hydrothermcally carbonized biomass wastes. Potential feedstock for the hydrothermal carbonization (HTC) includes variety of the non-traditional renewable wet agricultural and municipal waste streams. Pyrolysis and HTC show a comparable calor...

  20. Preparation of tourmaline nano-particles through a hydrothermal process and its infrared emission properties.

    PubMed

    Xue, Gang; Han, Chao; Liang, Jinsheng; Wang, Saifei; Zhao, Chaoyue

    2014-05-01

    Tourmaline nano-particles were successfully prepared via a hydrothermal process using HCl as an additive. The reaction temperature (T) and the concentration of HCI (C(HCl)) had effects on the size and morphology of the tourmaline nano-particles. The optimum reaction condition was that: T = 180 degrees C and C(HCl) = 0.1 mol/l. The obtained nano-particles were spherical with the diameter of 48 nm. The far-infrared emissivity of the product was 0.923. The formation mechnism of the tourmaline nano-particles might come from the corrosion of grain boundary between the tourmaline crystals in acidic hydrothermal conditions and then the asymmetric contraction of the crystals.

  1. Formation of serrated nanorods of hydroxyapatite through organic modification under hydrothermal processing

    NASA Astrophysics Data System (ADS)

    Prakash Parthiban, S.; Kim, Ill Yong; Kikuta, Koichi; Ohtsuki, Chikara

    2013-06-01

    Hydroxyapatite (HAp) ceramics are widely used as artificial bone substitutes owing to its unique biological activity, that is, bone-bonding property. HAp nanoparticles have higher potential of biological functionality than microparticles owing to their increased specific surface area (SSA) because biological functionality of the crystals is governed by their surface characteristics. HAp particles of varied size and morphology have been prepared by employing various kinds of surfactants and capping ligands. In this research, we report the formation of HAp nanorods with serrated morphology which led to an increase in SSA. We obtained HAp nanorods with serrated morphology by adding thiosalicylic acid as a capping ligand under hydrothermal conditions. The tailoring of HAp nanorods by thiosalicylic acid under hydrothermal conditions is a useful method to prepare HAp nanorods with improved functionality.

  2. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    NASA Astrophysics Data System (ADS)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2016-12-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  3. Hydrothermal etching preparation and growth process of γ-MnOOH with novel hexagram morphology

    NASA Astrophysics Data System (ADS)

    Yang, Xing; Zhou, Haiyan; Lv, Jing; Kang, Liping; Lei, Zhibin; Liu, Zong-huai

    2015-04-01

    Well-defined single crystal γ-MnOOH with novel hexagram morphology was prepared by hydrothermal treating a suspension of ethyl acetate and KMnO4 at 200 °C for 48 h, and its formation process had been investigated on the basis of XRD, FESEM, TEM, HRTEM, and SAED analyses. In keeping hydrothermal treatment temperature and reaction time, ethyl acetate played an important role in controlling the crystal phase and morphology of the obtained materials, which was used as both reducing agent and etchant. It hydrolyzed into acetic acid and ethanol slowly and caused an acidic reaction environment accompanied with hydrothermal reaction. The acetic acid was adsorbed on the lateral of γ-MnOOH with multiple branched nanorods, which caused a soft etching process and the lateral of the multiple branched nanorods became sharper and thinner and finally transformed into γ-MnOOH with hexagram morphology. The prepared γ-MnOOH with novel hexagram morphology is expected to be used for a fundamental study in surface science and for potential applications such as adsorbent, electro-catalyst, sensing and so on.

  4. Direct Growth of Crystalline Tungsten Oxide Nanorod Arrays by a Hydrothermal Process and Their Electrochromic Properties

    NASA Astrophysics Data System (ADS)

    Lu, Chih-Hao; Hon, Min Hsiung; Leu, Ing-Chi

    2017-04-01

    Transparent crystalline tungsten oxide nanorod arrays for use as an electrochromic layer have been directly prepared on fluorine-doped tin oxide-coated glass via a facile tungsten film-assisted hydrothermal process using aqueous tungsten hexachloride solution. X-ray diffraction analysis and field-emission scanning electron microscopy were used to characterize the phase and morphology of the grown nanostructures. Arrays of tungsten oxide nanorods with diameter of ˜22 nm and length of ˜240 nm were obtained at 200°C after 8 h of hydrothermal reaction. We propose a growth mechanism for the deposition of the monoclinic tungsten oxide phase in the hydrothermal environment. The tungsten film was first oxidized to tungsten oxide to provide seed sites for crystal growth and address the poor connection between the growing tungsten oxide and substrate. Aligned tungsten oxide nanorod arrays can be grown by a W thin film-assisted heterogeneous nucleation process with NaCl as a structure-directing agent. The fabricated electrochromic device demonstrated optical modulation (coloration/bleaching) at 632.8 nm of ˜41.2% after applying a low voltage of 0.1 V for 10 s, indicating the potential of such nanorod array films for use in energy-saving smart windows.

  5. Advanced Seismic Studies of the Endeavour Ridge: Understanding the Interplay among Magmatic, Hydrothermal, and Tectonic Processes at Mid-Ocean Ridges

    NASA Astrophysics Data System (ADS)

    Arnoux, G. M.; VanderBeek, B. P.; Morgan, J. V.; Hooft, E. E. E.; Toomey, D. R.; Wilcock, W. S. D.; Warner, M.

    2014-12-01

    At mid-ocean ridges magmatic, hydrothermal, and tectonic processes are linked. Understanding their interactions requires mapping magmatic systems and tectonic structures, as well as their relationship to hydrothermal circulation. Three-dimensional seismic images of the crust can be used to infer the size, shape, and location of magma reservoirs, in addition to the structure of the thermal boundary layer that connects magmatic and hydrothermal processes. Travel time tomography has often been used to study these processes, however, the spatial resolution of travel time tomography is limited. Three-dimensional full waveform inversion (FWI) is a state-of-the art seismic method developed for use in the oil industry to obtain high-resolution models of the velocity structure. The primary advantage of FWI is that it has the potential to resolve subsurface structures on the order of half the seismic wavelength—a significant improvement on conventional travel time tomography. Here, we apply anisotropic FWI to data collected on the Endeavour segment of the Juan de Fuca Ridge. Starting models for anisotropic P-wave velocity were obtained by travel time tomography [Weekly et al., 2014]. During FWI, the isotropic velocity model is updated and anisotropy is held constant. We have recovered low-velocity zones approximately 2-3 km beneath the ridge axis that likely correspond to a segmented magma-rich body and are in concert with those previously resolved using multi-channel seismic reflection methods. The segmented crustal magma body underlies all five known high-temperature hydrothermal vent fields along the Endeavour segment. A high-velocity zone, shallower than the observed low-velocity zones, underlies the southernmost hydrothermal vent field. This may be indicative of waning hydrothermal activity in which minerals are crystallizing beneath the vent field. Our FWI study of the Endeavour Ridge will provide the most detailed three-dimensional images of the crustal structure to

  6. Formation of Hydrothermal nontronite associated with microbial activity at the South Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Ta, Kaiwen; Peng, Xiaotong; Chen, Shun; Xu, Hengchao; Li, Jiwei; Jiang, Lei; Du, Mengran

    2015-04-01

    Nontronite is an ubiquitous clay minerals in marine sediments, microbial mediation of hydrothermal nontronite have been increasing. The deposits collected from Southern Atlantic Ridge were very friable with an obvious laminated to stromatolitic to highly porous structure, varying from red, black to light yellow indicate redox condition may undergo range from micro-oxidizing to reducing. Although microbial activity are revealed to play an important role in the formation of clay minerals in sediment, little is currently known about microbial communities that reside in nontronite associated with hydrothermal activity. Here, we used Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), nano secondary ion mass spectrometer (nanoSIMS) and molecular techniques to focus on potential mediation role of microbial in the nontronite formation of low-temperature hydrothermal deposits in South Atlantic Mid-ocean ridge. Our data suggest that the presences of abundant lamellar nontronite structures, as well as microbe-like mineralized morphologies similar to consistent with a biogenic origin. Nontronite in the lower zone of Fe-Mn oxyhydroxides are inferred to have been suboxic environment and their formation appear to be significantly controlled by the locus of redox conditions. Keywords: Nontronite, Microbial activity, Hydrothermal deposits, Biogenic origin.

  7. Hydrothermal activity recorded in post Noachian-aged impact craters on Mars

    NASA Astrophysics Data System (ADS)

    Turner, Stuart M. R.; Bridges, John C.; Grebby, Stephen; Ehlmann, Bethany L.

    2016-04-01

    Hydrothermal systems have previously been reported in ancient Noachian and Hesperian-aged craters on Mars using CRISM but not in Amazonian-aged impact craters. However, the nakhlite meteorites do provide evidence of Amazonian hydrothermal activity. This study uses CRISM data of 144 impact craters of ≥7 km diameter and 14 smaller craters (3-7 km diameter) within terrain mapped as Amazonian to search for minerals that may have formed as a result of impact-induced hydrothermal alteration or show excavation of ancient altered crust. No evidence indicating the presence of hydrated minerals was found in the 3-7 km impact craters. Hydrated minerals were identified in three complex impact craters, located at 52.42°N, 39.86°E in the Ismenius Lacus quadrangle, at 8.93°N, 141.28°E in Elysium, and within the previously studied Stokes crater. These three craters have diameters 20 km, 62 km, and 51 km. The locations of the hydrated mineral outcrops and their associated morphology indicate that two of these three impact craters—the unnamed Ismenius Lacus Crater and Stokes Crater—possibly hosted impact-induced hydrothermal systems, as they contain alteration assemblages on their central uplifts that are not apparent in their ejecta. Chlorite and Fe serpentine are identified within alluvial fans in the central uplift and rim of the Ismenius Lacus crater, whereas Stokes crater contains a host of Fe/Mg/Al phyllosilicates. However, excavation origin cannot be precluded. Our work suggests that impact-induced hydrothermalism was rare in the Amazonian and/or that impact-induced hydrothermal alteration was not sufficiently pervasive or spatially widespread for detection by CRISM.

  8. Hydrothermal processing of MSWI fly ash--towards new stable minerals and fixation of heavy metals.

    PubMed

    Bayuseno, A P; Schmahl, W W; Müllejans, Th

    2009-08-15

    A hydrothermal processing strategy of MSWI fly ash is presented for obtaining stable minerals with low toxic potential. Different hydrothermal conditions were tested to obtain high yields of new stable minerals. Experimental parameters including temperature, nature and molarity of alkali reagents, and reaction time were evaluated. The chemical stability of hydrothermal products was examined by the toxicity characteristic leaching procedure (TCLP) test and subsequent XRD for the leached residue. The significant amounts of Al-substituted 11A tobermorite and katoite in addition to minor amounts of zeolites were formed under experimental conditions at 0.5M NaOH, 180 degrees C for 48 h, however KOH treatment in a similar regime resulted in smaller amounts of Al-substituted 11A tobermorite and katoite. Similarly, a product of mixed Al-substituted 11A tobermorite and katoite could be formed from the washed fly ash treated in 0.5M NaOH at 180 degrees C for 48 h. Under the acidic condition, the treated fly ash exhibited an excellent stability of the mineral assemblage and less release of heavy metals relative to the untreated parent materials.

  9. Highly effective removal of Methylene Blue using functionalized attapulgite via hydrothermal process.

    PubMed

    Zhang, Zhifang; Wang, Wenbo; Wang, Aiqin

    2015-07-01

    Attapulgite (APT) has been frequently used for the adsorptive removal of dyes from aqueous solution owing to its unique one-dimensional nanoscale structure and low-cost, abundant, eco-friendly advantages. In this work, APT was functionalized under mild hydrothermal condition using chloroacetic acid (CA) with COOH functional groups to improve its adsorption properties. The effect of hydrothermal modification on the microstructure and physicochemical features of APT was investigated by Fourier transform infrared spectroscopy, X-ray diffraction and Field-emission scanning electron microscopy analyses. The effects of hydrothermal reaction parameters on the adsorption properties of modified APT were intensively investigated. It was revealed that the rearrangement of crystal structure and the surface functionalization of APT with COOH groups cause the surprising increase of adsorption capability for Methylene Blue (MB). The removal ratio of raw APT for MB is only 59.52%, while modified APT could almost completely remove MB in the 200 mg/L of MB solution with a removal ratio of 99.8%. The adsorption kinetics fitted pseudo second-order kinetic model, and the adsorption isotherm could be described with Langmuir isotherm model very well. The hydrogen-bonding interaction, electrostatic attraction and chemical association are the main driving force for the adsorption process.

  10. Metagenome and Metatranscriptome Revealed a Highly Active and Intensive Sulfur Cycle in an Oil-Immersed Hydrothermal Chimney in Guaymas Basin.

    PubMed

    He, Ying; Feng, Xiaoyuan; Fang, Jing; Zhang, Yu; Xiao, Xiang

    2015-01-01

    The hydrothermal vent system is a typical chemosynthetic ecosystem in which microorganisms play essential roles in the geobiochemical cycling. Although it has been well-recognized that the inorganic sulfur compounds are abundant and actively converted through chemosynthetic pathways, the sulfur budget in a hydrothermal vent is poorly characterized due to the complexity of microbial sulfur cycling resulting from the numerous parties involved in the processes. In this study, we performed an integrated metagenomic and metatranscriptomic analysis on a chimney sample from Guaymas Basin to achieve a comprehensive study of each sulfur metabolic pathway and its hosting microorganisms and constructed the microbial sulfur cycle that occurs in the site. Our results clearly illustrated the stratified sulfur oxidation and sulfate reduction at the chimney wall. Besides, sulfur metabolizing is closely interacting with carbon cycles, especially the hydrocarbon degradation process in Guaymas Basin. This work supports that the internal sulfur cycling is intensive and the net sulfur budget is low in the hydrothermal ecosystem.

  11. System and process for efficient separation of biocrudes and water in a hydrothermal liquefaction system

    SciTech Connect

    Elliott, Douglas C.; Hart, Todd R.; Neuenschwander, Gary G.; Oyler, James R.; Rotness, Jr, Leslie J.; Schmidt, Andrew J.; Zacher, Alan H.

    2016-08-02

    A system and process are described for clean separation of biocrudes and water by-products from hydrothermal liquefaction (HTL) product mixtures of organic and biomass-containing feedstocks at elevated temperatures and pressures. Inorganic compound solids are removed prior to separation of biocrude and water by-product fractions to minimize formation of emulsions that impede separation. Separation may be performed at higher temperatures that reduce heat loss and need to cool product mixtures to ambient. The present invention thus achieves separation efficiencies not achieved in conventional HTL processing.

  12. A multi-faceted approach to characterize acid-sulfate alteration processes in volcanic hydrothermal systems on Earth and Mars

    NASA Astrophysics Data System (ADS)

    Marcucci, Emma Cordts

    Acid-sulfate alteration is a dominant weathering process in high temperature, low pH, sulfur-rich volcanic environments. Additionally, hydrothermal environments have been proposed as locations where life could have originated on Earth. Based on the extensive evidence of flowing surface water and persistent volcanism, similar locations and processes could have existed on early Mars. Globally observed alteration mineral assemblages likely represent relic Martian hydrothermal settings. Yet the limited understanding of environmental controls, limits the confidence of interpreting the paleoconditions of these hydrothermal systems and assessing their habitability to support microbial life. This thesis presents a series of laboratory experiments, geochemical models, analog fieldwork, and Martian remote sensing to characterize distinguishing features and controls of acid-sulfate alteration. The experiments and models were designed to replicate alteration is a highly acidic, sulfurous, and hot field sites. The basaltic minerals were individually reacted in both experimental and model simulations with varying initial parameters to infer the geochemical pathways of acid-sulfate alteration on Earth and Mars. It was found that for a specific starting material, secondary mineralogies were consistent. Variations in pH, temperature and duration affected the abundance, shape, and size of mineral products. Additionally evaporation played a key role in secondary deposits; therefore, both alteration and evaporitic processes need to be taken into consideration. Analog volcanic sites in Nicaragua were used to supplement this work and highlight differences between natural and simulated alteration. In situ visible near-infrared spectroscopy demonstrated that primary lithology and gas chemistry were dominant controls of alteration, with secondary effects from environmental controls, such as temperature and pH. The spectroscopic research from the field was directly related to Mars

  13. Hydrothermal Synthesis and Processing of Barium Titanate Nanoparticles Embedded in Polymer Films.

    PubMed

    Toomey, Michael D; Gao, Kai; Mendis, Gamini P; Slamovich, Elliott B; Howarter, John A

    2015-12-30

    Barium titanate nanoparticles embedded in flexible polymer films were synthesized using hydrothermal processing methods. The resulting films were characterized with respect to material composition, size distribution of nanoparticles, and spatial location of particles within the polymer film. Synthesis conditions were varied based on the mechanical properties of the polymer films, ratio of polymer to barium titanate precursors, and length of aging time between initial formulations of the solution to final processing of nanoparticles. Block copolymers of poly(styrene-co-maleic anhydride) (SMAh) were used to spatially separate titanium precursors based on specific chemical interactions with the maleic anhydride moiety. However, the glassy nature of this copolymer restricted mobility of the titanium precursors during hydrothermal processing. The addition of rubbery butadiene moieties, through mixing of the SMAh with poly(styrene-butadiene-styrene) (SBS) copolymer, increased the nanoparticle dispersion as a result of greater diffusivity of the titanium precursor via higher mobility of the polymer matrix. Additionally, an aminosilane was used as a means to retard cross-linking in polymer-metalorganic solutions, as the titanium precursor molecules were shown to react and form networks prior to hydrothermal processing. By adding small amounts of competing aminosilane, excessive cross-linking was prevented without significantly impacting the quality and composition of the final barium titanate nanoparticles. X-ray diffraction and X-ray photoelectron spectroscopy were used to verify nanoparticle compositions. Particle sizes within the polymer films were measured to be 108 ± 5 nm, 100 ± 6 nm, and 60 ± 5 nm under different synthetic conditions using electron microscopy. Flexibility of the films was assessed through measurement of the glass transition temperature using dynamic mechanical analysis. Dielectric permittivity was measured using an impedance analyzer.

  14. East Pacific rise at 21°N: the volcanic, tectonic, and hydrothermal processes of the central axis

    USGS Publications Warehouse

    Ballard, Richard D.; Francheteau, Jean; Juteau, Tierre; Rangan, Claude; Normark, William

    1981-01-01

    Photographs obtained by the ANGUS survey system at 21°N reveal many similarities to the geological processes delineated at other spreading centers and in particular those observed in the Galapagos Rift at 86°W. The region of recent volcanism is restricted to a narrow zone (Zone 1) approximately 1 km wide. This suggests that the width of the magma chamber feeding these flows is also narrow at the top. Variations in sediment cover are used to subdivide the flows within Zone 1 into three sheet-flow/pillow-flow pairs. The youngest pair appears to have erupted form a linear fissure 8 km long running parallel to the valley axis. This fissure is part of a larger en echelon pattern of eruptive fissures. Active hydrothermal vents associated with the youngest flows are situated directly above the apparent eruptive fissure. The high (350°C) temperature for some of the fluids exiting from the vents suggests a highly restricted circulation system involving, at times, little to no mixing with cold seawater. The lava terrain in the remainder of Zone 1 and bordering regions is characterized by extensive fracturing, further suggesting a narrow upper dimension to the magma chamber and also that subsurface hydrothermal deposition of massive sulfides may lead to a reduction in the mixing processes.

  15. Antimicrobial Activity of Marine Bacterial Symbionts Retrieved from Shallow Water Hydrothermal Vents.

    PubMed

    Eythorsdottir, Arnheidur; Omarsdottir, Sesselja; Einarsson, Hjorleifur

    2016-06-01

    Marine sponges and other sessile macro-organisms were collected at a shallow water hydrothermal site in Eyjafjörður, Iceland. Bacteria were isolated from the organisms using selective media for actinomycetes, and the isolates were screened for antimicrobial activity. A total of 111 isolates revealed antimicrobial activity displaying different antimicrobial patterns which indicates production of various compounds. Known test strains were grown in the presence of ethyl acetate extracts from one selected isolate, and a clear growth inhibition of Staphylococcus aureus was observed down to 0.1 % extract concentration in the medium. Identification of isolates shows different species of Actinobacteria with Streptomyces sp. playing the largest role, but also members of Bacilli, Alphaproteobacteria and Gammaproteobacteria. Sponges have an excellent record regarding production of bioactive compounds, often involving microbial symbionts. At the hydrothermal vents, however, the majority of active isolates originated from other invertebrates such as sea anemones or algae. The results indicate that antimicrobial assays involving isolates in full growth can detect activity not visible by other methods. The macro-organisms inhabiting the Eyjafjörður hydrothermal vent area host diverse microbial species in the phylum Actinobacteria with antimicrobial activity, and the compounds responsible for the activity will be subject to further research.

  16. Coastal submarine hydrothermal activity of Northern Baja California 2. Evolutionary history and isotope geochemistry

    SciTech Connect

    Vidal, V.M.V.; Vidal, F.V.; Isaacs, J.D.

    1981-10-10

    A geochemical model of the Punta Banda submarine hydrothermal system (PBSHS) and Ensenada quadrangle subaerial hot springs is developed using /sup 18/O//sup 16/O, D/H, /sup 34/S//sup 32/S, /sup 3/H, water and gas chemistry. The PBSHS water is a primary high temperature, acid, reducing fluid of old seawater origin which has been titrated by cold, alkaline groundwater of meteoric origin. The final exiting solutions represent a 1:1 mixture of the two primary mixing components. In contrast, the subaerial hot spring waters are of unmixed meteoric origin. The subaerial hot spring gas is predominantly atmospheric N/sub 2/, while the PBSHS contains large amounts of CH/sub 4/ and N/sub 2/ derived from trapped marine sediments of Cretaceous age, deltaS/sup 34/ values of sampled hydrothermal waters are similar to Cretaceous marine sulfate values and suggest that the waters contacted Cretaceous marine sedimentary strata. The presence of the Alisitos and Rosario marine sedimentary formations of Cretaceous age within the Ensenada-Punta Banda quadrangel renders support to the above hypothesis. The data also demonstrate the pyrite mineralization and deposition in submarine hydrothermal environments result from the complexing of ferrous iron with elemental sulfur and sulfide and that submarine hydrothermal activity acts as a major source of silica, Ca/sup 2 +/, and trace metals and as a major sink for seawater Mg/sup 2 +/ and SO/sub 4//sup 2 -/.

  17. Rare earth elements as indicators of hydrothermal processes within the East Scotia subduction zone system

    NASA Astrophysics Data System (ADS)

    Cole, Catherine S.; James, Rachael H.; Connelly, Douglas P.; Hathorne, Ed C.

    2014-09-01

    The East Scotia subduction zone, located in the Atlantic sector of the Southern Ocean, hosts a number of hydrothermal sites in both back-arc and island-arc settings. High temperature (>348 °C) 'black smoker' vents have been sampled at three locations along segments E2 and E9 of the East Scotia back-arc spreading ridge, as well as 'white smoker' (<212 °C) and diffuse (<28 °C) hydrothermal fluids from within the caldera of the Kemp submarine volcano. The composition of the endmember fluids (Mg = 0 mmol/kg) is markedly different, with pH ranging from <1 to 3.4, [Cl-] from ∼90 to 536 mM, [H2S] from 6.7 to ∼200 mM and [F-] from 35 to ∼1000 μM. All of the vent sites are basalt- to basaltic andesite-hosted, providing an ideal opportunity for investigating the geochemical controls on rare earth element (REE) behaviour. Endmember hydrothermal fluids from E2 and E9 have total REE concentrations ranging from 7.3 to 123 nmol/kg, and chondrite-normalised distribution patterns are either light REE-enriched (LaCN/YbCN = 12.8-30.0) with a positive europium anomaly (EuCN/Eu∗CN = 3.45-59.5), or mid REE-enriched (LaCN/NdCN = 0.61) with a negative Eu anomaly (EuCN/Eu∗CN = 0.59). By contrast, fluids from the Kemp Caldera have almost flat REE patterns (LaCN/YbCN = 2.1-2.2; EuCN/Eu∗CN = 1.2-2.2). We demonstrate that the REE geochemistry of fluids from the East Scotia back-arc spreading ridge is variably influenced by ion exchange with host minerals, phase separation, competitive complexation with ligands, and anhydrite deposition, whereas fluids from the Kemp submarine volcano are also affected by the injection of magmatic volatiles which enhances the solubility of all the REEs. We also show that the REE patterns of anhydrite deposits from Kemp differ from those of the present-day fluids, potentially providing critical information about the nature of hydrothermal activity in the past, where access to hydrothermal fluids is precluded.

  18. Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Fredriksson, Kurt; Goetzinger, Michael; Reimold, Wolf Uwe

    1989-01-01

    Quartz pebbles from the Roter Kamm impact crater (the Namib Desert, SWA/Namibia) were examined for evidence of impact-induced hydrothermal activity, using results from microprobe analyses, neutron activation analyses, transmission IR spectroscopy, and X-ray diffractometry. It was found that the pebbles consisted of pure quartz, which contains three different types of fluid inclusions. These were identified as primary inclusions (5-10 microns) that record the formation conditions of the quartz, very small (less than 1 micron) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. It is concluded that the quartz and the primary inclusions may provide evidence for a postimpact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  19. Hydrothermal activity along the northern Mid-Atlantic Ridge and in the Bransfield Strait Backarc Basin, Antarctica

    NASA Astrophysics Data System (ADS)

    Chin, Carol S.

    1998-12-01

    Seafloor hydrothermal circulation through young oceanic crust results in the expulsion of fluids as both diffuse and focused flow in the form of hydrothermal venting. High-temperature hydrothermal fluids are enriched in reduced chemical species that rapidly oxidize upon interaction with ambient, oxygen-rich bottom waters, resulting in plumes that are detectable in the water column both by their dissolved chemical composition as well as by their particle concentration. This study employed a novel instrument package which detected both dissolved manganese and particle concentration in situ. This package also included a standard CTD (conductivity, temperature, depth) and rosette for the collection of water samples. Because hydrothermal plumes integrate the output from an entire vent field, measurements in plumes can be used to estimate vent field fluxes. Some geochemical tracers from hydrothermal vents can also be detected thousands of kilometers from their sources. Thus, plumes provide the means to prospect for undiscovered hydrothermal sites, and can also predict characteristics of the venting site. This work includes studies of hydrothermal plumes along the northern Mid-Atlantic Ridge and in the Bransfield Strait backarc basin, Antarctica. In recent years, the number of known hydrothermal sites on the Mid-Atlantic Ridge (MAR) has increased from two to seven, and most other segments between 12° and 41° N have shown evidence of high-temperature hydrothermal activity. Furthermore, it appears that as one approaches the Azores Plateau, the concentration of dissolved delta3He in the bottom water (originating from hydrothermal venting) increases, suggesting that hydrothermal activity increases toward the plateau. This is consistent with the significant tectonic extension and crustal fissuring observed near the Azores Platform, which is expected to support increased convection. The Bransfield Strait is a backarc basin between the Antarctic Peninsula and the South

  20. Process Development for Hydrothermal Liquefaction of Algae Feedstocks in a Continuous-Flow Reactor

    SciTech Connect

    Elliott, Douglas C.; Hart, Todd R.; Schmidt, Andrew J.; Neuenschwander, Gary G.; Rotness, Leslie J.; Olarte, Mariefel V.; Zacher, Alan H.; Albrecht, Karl O.; Hallen, Richard T.; Holladay, Johnathan E.

    2013-10-01

    Wet algae slurries can be converted into an upgradeable biocrude by hydrothermal liquefaction (HTL). High levels of carbon conversion to gravity-separable biocrude product were accomplished at relatively low temperature (350 °C) in a continuous-flow, pressurized (sub-critical liquid water) environment (20 MPa). As opposed to earlier work in batch reactors reported by others, direct oil recovery was achieved without the use of a solvent and biomass trace components were removed by processing steps so that they did not cause process difficulties. High conversions were obtained even with high slurry concentrations of up to 35 wt% of dry solids. Catalytic hydrotreating was effectively applied for hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization of the biocrude to form liquid hydrocarbon fuel. Catalytic hydrothermal gasification was effectively applied for HTL byproduct water cleanup and fuel gas production from water soluble organics, allowing the water to be considered for recycle of nutrients to the algae growth ponds. As a result, high conversion of algae to liquid hydrocarbon and gas products was found with low levels of organic contamination in the byproduct water. All three process steps were accomplished in bench-scale, continuous-flow reactor systems such that design data for process scale-up was generated.

  1. Significant role of climatic trends on hydrothermal activity Coso Hot Springs, California

    SciTech Connect

    Lofgren, B.E. )

    1990-05-01

    The hydrothermal features of Coso Hot Springs have attracted visitors for 130 yr and scientific investigators for two decades. In 1978, anticipating effects of major geothermal developments nearby, the Naval Weapons Center (NWC) initiated a comprehensive monitoring program at a dozen hydrothermal sites in the Coso Hot Springs area. Nine years of monitoring preceded power production in the nearby Coso geothermal field in July 1987. During this period, steam was rising from numerous vents and gently boiling mud pots. Local rainfall caused increased boiling activity in several mud pots, with some overflowing during wet periods. Then in August 1988, a year after geothermal power production began major changes in hot spring activity commenced. Small mud pots and steamers started to grow and coalesce. In March 1989, mud-pot activity became more violent. Many buried wells failed causing surface activity in other areas to diminish. During ensuing months, large mud cones developed and much of the steam and boiling water occurred in a few major pots. Because the abrupt changes in hydrothermal activity followed so closely after nearby geothermal production began, the obvious cause has been attributed to geothermal developments. Studies of NWC baseline monitoring data indicate, however, that no effects of geothermal developments have been felt in the hot springs area. Rainfall and barometric effects account for most of the fluctuations in records of the past decade. Early accounts and field evidence suggest similar changes have occurred in the past.

  2. CONDENSED MATTER: STRUCTURE, MECHANICAL AND THERMAL PROPERTIES: CuO Nanosheets Synthesized by Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Jiang, Zhi-Ang; Chen, Jiang-Tao; Wang, Jun; Zhuo, Ren-Fu; Yan, De; Zhang, Fei; Yan, Peng-Xun

    2009-08-01

    CuO nanosheets are synthesized by oxidation of commercial Cu substrates through the hydrothermal process at 150°C. The as-synthesized nanosheets are characterized by powder x-ray diffraction, transmission electron microscopy, selected area electron diffraction and x-ray photoelectron spectroscopy. For comparison, Cu substrates are also oxidized without NaOH added in precursor solution. The results show that the morphology of CuO could be controlled by NaOH, which demonstrates that NaOH can serve as a cosolvent and modifier in the reaction system. The possible mechanism of the growth of CuO nanosheets is also discussed.

  3. Hydrothermal Petroleum in Active Continental Rift: Lake Chapala, Western Mexico, Initial Results.

    NASA Astrophysics Data System (ADS)

    Zarate-del Valle, P. F.; Simoneit, B. R.; Ramirez-Sanchez, H. U.

    2003-12-01

    Lake Chapala in western Mexico is located partially in the Citala Rift, which belongs to the well-known neotectonic Jalisco continental triple junction. The region is characterized by active volcanism (Ceboruco, Volcan de Fuego), tectonic (1995 earthquake, M=8, 40-50 mm to SW) and hydrothermal (San Juan Cosala & Villa Corona spas and La Calera sinter deposit) activities. Hydrothermal petroleum has been described in active continental rift (East African Rift) and marine spreading zones (Guaymas Basin, Gulf of California). In 1868 the Mexican local press reported that manifestations of bitumen were appearing in front of the Columba Cap on the mid south shore of Lake Chapala. This bitumen is linked to the lake bottom and when the water level decreases sufficiently it is possible to access these tar bodies as islands. Because of these manifestations the Mexican oil company (PEMEX) drilled an exploration well (2,348m) at Tizapan El Alto without success. Hydrothermal activity is evident in the tar island zone as three in-shore thermal springs (26.8 m depth, 48.5° C, pH 7.8 and oriented N-S). The preliminary analyses by GC-MS of the tar from these islands indicate hydrothermal petroleum derived from lake sedimentary organic matter, generated at low temperatures (150° -200° C). The tars contain no n-alkanes, no PAH or other aromatics, but a major UCM of branched and cyclic hydrocarbons and mature biomarkers derived from lacustrine biota. The biomarkers consist of mainly 17α (H),21β (H)-hopanes ranging from C27 to C34 (no C28), gammacerane, tricyclic terpanes (C20-C26), carotane and its cracking products, and drimanes (C14-C16). The biomarker composition indicates an organic matter source from bacteria and algae, typical of lacustrine ecosystems. 14C dating of samples from two tar islands yielded ages exceeding 40 kyrs, i.e., old carbon from hydrothermal/tectonic remobilization of bitumen from deeper horizons to the surface. The occurrence of hydrothermal petroleum in

  4. Hydrothermal activity along the slow-spreading Lucky Strike ridge segment (Mid-Atlantic Ridge): Distribution, heatflux, and geological controls

    NASA Astrophysics Data System (ADS)

    Escartin, J.; Barreyre, T.; Cannat, M.; Garcia, R.; Gracias, N.; Deschamps, A.; Salocchi, A.; Sarradin, P.-M.; Ballu, V.

    2015-12-01

    We have reviewed available visual information from the seafloor, and recently acquired microbathymetry for several traverses across the Lucky Strike segment, to evaluate the distribution of hydrothermal activity. We have identified a new on-axis site with diffuse flow, Ewan, and an active vent structure ∼1.2 km from the axis, Capelinhos. These sites are minor relative to the Main field, and our total heatflux estimate for all active sites (200-1200 MW) is only slightly higher than previously published estimates. We also identify fossil sites W of the main Lucky Strike field. A circular feature ∼200 m in diameter located on the flanks of a rifted off-axis central volcano is likely a large and inactive hydrothermal edifice, named Grunnus. We find no indicator of focused hydrothermal activity elsewhere along the segment, suggesting that the enhanced melt supply and the associated melt lenses, required to form central volcanoes, also sustain hydrothermal circulation to form and maintain large and long-lived hydrothermal fields. Hydrothermal discharge to the seafloor occurs along fault traces, suggesting focusing of hydrothermal circulation in the shallow crust along permeable fault zones.

  5. Seafloor hydrothermal activity and spreading rates - The Eocene carbon dioxide greenhouse revisited

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.; Richardson, S. M.

    1985-01-01

    A suggestion has been made that enhanced rates of hydrothermal activity during the Eocene could have caused a global warming by adding calcium to the ocean and pumping CO2 into the atmosphere (Owen and Rea, 1984). This phenomenon was purported to be consistent with the predictions of the CO2 geochemical cycle model of Berner, Lasaga and Garrels (1983) (henceforth BLAG). In fact, however, the BLAG model predicts only a weak connection between hydrothermal activity and atmospheric CO2 levels. By contrast, it predicts a strong correlation between seafloor spreading rates and pCO2, since the release rate of CO2 from carbonate metamorphism is assumed to be proportional to the mean spreading rate. The Eocene warming can be conveniently explained if the BLAG model is extended by assuming that the rate of carbonate metamorphism is also proportional to the total length of the midocean ridges from which the spreading originates.

  6. Seafloor hydrothermal activity and spreading rates: the Eocene carbon dioxide greenhouse revisted

    NASA Technical Reports Server (NTRS)

    Kasting, J. F.; Richardson, S. M.

    1985-01-01

    A suggestion has been made that enhanced rates of hydrothermal activity during the Eocene could have caused a global warming by adding calcium to the ocean and pumping CO2 into the atmosphere (Owen and Rea, 1984). This phenomenon was purported to be consistent with the predictions of the CO2 geochemical cycle model of Berner, Lasaga and Garrels (1983) (henceforth BLAG). In fact, however, the BLAG model predicts only a weak connection between hydrothermal activity and atmospheric CO2 levels. By contrast, it predicts a strong correlation between seafloor spreading rates and pCO2, since the release rate of CO2 from carbonate metamorphism is assumed to be proportional to the mean spreading rate. The Ecocene warming can be conveniently explained if the BLAG model is extended by assuming that the rate of carbonate metamorphism is also proportional to the total length of the midocean ridges from which the spreading originates.

  7. Seafloor hydrothermal activity and spreading rates: the Eocene carbon dioxide greenhouse revisted.

    PubMed

    Kasting, J F; Richardson, S M

    1985-01-01

    A suggestion has been made that enhanced rates of hydrothermal activity during the Eocene could have caused a global warming by adding calcium to the ocean and pumping CO2 into the atmosphere (Owen and Rea, 1984). This phenomenon was purported to be consistent with the predictions of the CO2 geochemical cycle model of Berner, Lasaga and Garrels (1983) (henceforth BLAG). In fact, however, the BLAG model predicts only a weak connection between hydrothermal activity and atmospheric CO2 levels. By contrast, it predicts a strong correlation between seafloor spreading rates and pCO2, since the release rate of CO2 from carbonate metamorphism is assumed to be proportional to the mean spreading rate. The Ecocene warming can be conveniently explained if the BLAG model is extended by assuming that the rate of carbonate metamorphism is also proportional to the total length of the midocean ridges from which the spreading originates.

  8. Elaboration of a video processing platform to analyze the temporal dynamics of hydrothermal ecosystems

    NASA Astrophysics Data System (ADS)

    Aron, M.; Sarrazin, J.; Sarradin, P.; Mercier, G.

    2010-12-01

    Located on oceanic ridges, hydrothermal ecosystems are characterized by strong physicochemical gradients and the presence of a unique fauna, sustained by microbial chemosynthesis. Several studies have shown that the spatial distribution and composition of vent faunal assemblages were strongly correlated to geological, physical and chemical processes at different spatial and temporal scales, but almost no data are available on the temporal dynamics of these peculiar ecosystems. The objective of our research is to develop a video processing platform to automatically extract the biological, physical and geological data from video imagery in order to study the dynamics of the fauna and its habitat in hydrothermal ecosystems. The video data was acquired from the Tempo-mini module deployed at 100m depth in the Saanich inlet (BC, Canada) and connected to the VENUS cable observatory (http://www.venus.uvic.ca/). This submarine color video-camera acquired four months of video footage, representing 487944 images of typical benthic habitat. A first manual extraction of the data allowed us to identify the key data available on a small subset of the video sequences. The objective of the new processing tool is to automatically extract these key data on the whole dataset, using unsupervized or lightly supervized image processing technique adapted to the specificity of submarines images. Firstly, all the moving objects in the video frames were segmented and labelled, allowing us to use statistical methods to process very large datasets. Secondly, computer vision techniques were used in order to get metric and 3D information from the images. For example, the speed of the moving objects and the image surface area were computed. The method implies the calibration of the camera with a calibration target, i.e. computing the projective geometric properties of the camera and the scene. Lastly, the developed tools will be integrated in a user-friendly processing platform that will be used

  9. Carbon Isotope Systematics in Mineral-Catalyzed Hydrothermal Organic Synthesis Processes at High Temperature and Pressures

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, R. A.; Niles, Paul B.

    2011-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques. Reduction of CO2 and/or CO during serpentization by mineral surface catalyzed Fischer-Tropsch Type (FTT) synthesis may be one possible process responsible for methane generation on Mars. With the evidence a recent study has discovered for serpentinization in deeply buried carbon rich sediments, and more showing extensive water-rock interaction in Martian history, it seems likely that abiotic methane generation via serpentinization reactions may have been common on Mars. Experiments involving mineral-catalyzed hydrothermal organic synthesis processes were conducted at 750 C and 5.5 Kbars. Alkanes, alcohols and carboxylic acids were identified as organic compounds. No "isotopic reversal" of delta C-13 values was observed for alkanes or carboxylic acids, suggesting a different reaction pathway than polymerization. Alcohols were proposed as intermediaries formed on mineral surfaces at experimental conditions. Carbon isotope data were used in this study to unravel the reaction pathways of abiotic formation of organic compounds in hydrothermal systems at high temperatures and pressures. They are instrumental in constraining the origin and evolution history of organic compounds on Mars and other planets.

  10. PH Tester Gauge Repeatability and Reproducibility Study for WO3 Nanostructure Hydrothermal Growth Process

    NASA Astrophysics Data System (ADS)

    Abd Rashid, Amirul; Hayati Saad, Nor; Bien Chia Sheng, Daniel; Yee, Lee Wai

    2014-06-01

    PH value is one of the important variables for tungsten trioxide (WO3) nanostructure hydrothermal synthesis process. The morphology of the synthesized nanostructure can be properly controlled by measuring and controlling the pH value of the solution used in this facile synthesis route. Therefore, it is very crucial to ensure the gauge used for pH measurement is reliable in order to achieve the expected result. In this study, gauge repeatability and reproducibility (GR&R) method was used to assess the repeatability and reproducibility of the pH tester. Based on ANOVA method, the design of experimental metrics as well as the result of the experiment was analyzed using Minitab software. It was found that the initial GR&R value for the tester was at 17.55 % which considered as acceptable. To further improve the GR&R level, a new pH measuring procedure was introduced. With the new procedure, the GR&R value was able to be reduced to 2.05%, which means the tester is statistically very ideal to measure the pH of the solution prepared for WO3 hydrothermal synthesis process.

  11. [Impact of hydrothermal process on the dewaterability and degrease performance of restaurant garbage].

    PubMed

    Ren, Lian-hail; Nie, Yong-feng; Liu, Jian-guo; Jin, Yi-ying

    2006-09-01

    In order to ameliorate the dewaterability and degrease performance of restaurant garbage, and to improve the treatment effect, a complete trail series with 2 factors on 5 levels was implemented. The 2 factors were temperature and retention time respectively as the main influencing factors of hydrothermal process. By means of analyzing the variation of the resistance, dewatering rate and floatable oil content of the treated restaurant garbage, and constructing the solid grease extracting kinetics, the mechanism of impact of hydrothermal process on the dewaterability and degrease performance of restaurant garbage was studied. It showed that the dewaterability of the product decreases at the beginning, after heating for 40min, it begins to increase. Moreover, it increases more quickly as temperature increases. The optimal dewaterability of the treated garbage appears at 180 degrees C and heating for 100 minutes. As temperature rises and heating time increases, the degrease performance is improved. Furthermore, this trend becomes more remarkably as temperature increases. When the temperature and retention time reach 160 degrees C and 80 minutes respectively, most of the solid grease in the garbage is extracted out to become floatable oil which can be separated and recovered readily. Subsequently, the amount of floatable oil begins to decrease since chemical reactions such as the partial hydrolysis of the oil take place. Additionally, the extraction of solid grease from interior accords with first-order reaction dynamic model.

  12. Fabrication of hollow mesoporous NiO hexagonal microspheres via hydrothermal process in ionic liquid

    SciTech Connect

    Zhao, Jinbo; Wu, Lili; Zou, Ke

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Ni(OH){sub 2} precursors were synthesized in ionic liquid and water solution by hydrothermal method. Black-Right-Pointing-Pointer NiO hollow microspheres were prepared by thermal treatment of Ni(OH){sub 2} precursors. Black-Right-Pointing-Pointer NiO hollow microspheres were self-assembled by mesoporous cubic and hexagonal nanocrystals with high specific surface area. Black-Right-Pointing-Pointer The mesoporous structure is stable at 773 K. Black-Right-Pointing-Pointer The ionic liquid absorbed on the O-terminate surface of the crystals to form hydrogen bond and played key roles in determining the final shape of the NiO novel microstructure. -- Abstract: The novel NiO hexagonal hollow microspheres have been successfully prepared by annealing Ni(OH){sub 2}, which was synthesized via an ionic liquid-assisted hydrothermal method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), N{sub 2} adsorption-desorption and Fourier transform infrared spectrometer (FTIR). The results show that the hollow NiO microstructures are self-organized by mesoporous cubic and hexagonal nanocrystals. The mesoporous structure possessed good thermal stability and high specific surface area (ca. 83 m{sup 2}/g). The ionic liquid 1-butyl-3methylimidazolium tetrafluoroborate ([Bmim][BF{sub 4}]) was found to play a key role in controlling the morphology of NiO microstructures during the hydrothermal process. The special hollow mesoporous architectures will have potential applications in many fields, such as catalysts, absorbents, sensors, drug-delivery carriers, acoustic insulators and supercapacitors.

  13. Phases' characteristics of poultry litter hydrothermal carbonization under a range of process parameters.

    PubMed

    Mau, Vivian; Quance, Julie; Posmanik, Roy; Gross, Amit

    2016-11-01

    The aim of this work was to study the hydrothermal carbonization of poultry litter under a range of process parameters. Experiments were conducted to investigate the effect of HTC of poultry litter under a range of operational parameters (temperature, reaction time, and solids concentration) on the formation and characteristics of its phases. Results showed production of a hydrochar with caloric value of 24.4MJ/kg, similar to sub-bituminous coal. The gaseous phase consisted mainly of CO2. However, significant amounts of H2S dictate the need for (further) treatment. The process also produced an aqueous phase with chemical characteristics suggesting its possible use as a liquid fertilizer. Temperature had the most significant effect on processes and product formation. Solids concentration was not a significant factor once dilution effects were considered.

  14. A comparison of product yields and inorganic content in process streams following thermal hydrolysis and hydrothermal processing of microalgae, manure and digestate.

    PubMed

    Ekpo, U; Ross, A B; Camargo-Valero, M A; Williams, P T

    2016-01-01

    Thermal hydrolysis and hydrothermal processing show promise for converting biomass into higher energy density fuels. Both approaches facilitate the extraction of inorganics into the aqueous product. This study compares the behaviour of microalgae, digestate, swine and chicken manure by thermal hydrolysis and hydrothermal processing at increasing process severity. Thermal hydrolysis was performed at 170°C, hydrothermal carbonisation (HTC) was performed at 250°C, hydrothermal liquefaction (HTL) was performed at 350°C and supercritical water gasification (SCWG) was performed at 500°C. The level of nitrogen, phosphorus and potassium in the product streams was measured for each feedstock. Nitrogen is present in the aqueous phase as organic-N and NH3-N. The proportion of organic-N is higher at lower temperatures. Extraction of phosphorus is linked to the presence of inorganics such as Ca, Mg and Fe in the feedstock. Microalgae and chicken manure release phosphorus more easily than other feedstocks.

  15. Meteorite organics in planetary environments: hydrothermal release, surface activity, and microbial utilization

    NASA Technical Reports Server (NTRS)

    Mautner, M. N.; Leonard, R. L.; Deamer, D. W.

    1995-01-01

    Up to 50% of the organics in the Murchison meteorite, possibly including some of the polymer, is released in high temperature and pressure aqueous environments, to 350 degrees C and 250 bar, that simulate submarine volcanic, hydrothermal or impact-induced conditions. Meteorite organics of prebiotic significance, such as nonanoic acid, glycine, and pyrene survive the hydrothermal conditions. The released material is surface active with surface pressures up to 19.8 x 10(-3) N m-1, and exhibits an extended surface tension isotherm which suggests a mixture of amphiphilic components. One component, nonanoic acid, is shown to form vesicles. The materials extracted under mild conditions, at 120 degrees C, are nutrients for the humic acid bacterium Pseudomonas maltophilia and efficient nutrients for the oligotroph Flavobacterium oryzihabitans, demonstrating the capability of microorganisms to metabolize extraterrestrial organics.

  16. Meteorite organics in planetary environments: hydrothermal release, surface activity, and microbial utilization

    NASA Astrophysics Data System (ADS)

    Mautner, Michael N.; Leonard, Robert L.; Deamer, David W.

    1995-02-01

    Up to 50% of the organics in the Murchison meteorite, possibly including some of the polymer, is released in high temperature and pressure aqueous environments, to 350°C and 250 bar, that simulate submarine volcanic, hydrothermal or impact-induced conditions. Meteorite organics of prebiotic significance, such as nonanoic acid, glycine, and pyrene survive the hydrothermal conditions. The released material is surface active with surface pressures up to 19.8 × 10 -3 N m -1, and exhibits an extended surface tension isotherm which suggests a mixture of amphiphilic components. One component, nonanoic acid, is shown to form vesicles. The materials extracted under mild conditions, at 120°C, are nutrients for the humic acid bacterium Pseudomonas maltophilia and efficient nutrients for the oligotroph Flavobacterium oryzihabitans, demonstrating the capability of micro-organisms to metabolize extraterrestrial organics.

  17. Holocene carbonate record of Lake Kivu reflects the history of hydrothermal activity.

    PubMed

    Votava, Jillian E; Johnson, Thomas C; Hecky, Robert E

    2017-01-10

    The sediment record of Lake Kivu reveals a complex volcanogenic and climatic Holocene history. Investigation of the inorganic carbonate record dates the onset of carbonate deposition in the mid-Holocene in Kivu's deep northern and eastern basins and identifies conditions enabling deposition. The magnitude and timing of carbonate-rich sedimentation is not so much controlled by climate but, instead, linked strongly to hydrothermal activity in the basin. Sublacustrine springs supply the vast majority of the calcium and carbonate ions required for supersaturation with respect to aragonite. This major hydrothermal activity that permanently stratifies Lake Kivu today was initiated ∼3,100 y before present (3.1 ka), when carbonate-rich sediments first appeared in the Holocene record. Aragonite is the dominant CaCO3 mineral present in the lake deposits. Both δ(13)C and δ(18)O of the aragonite are enriched above the expected kinetic fractionation of meteoric waters, suggesting a volcanogenic influence on the formation waters. Repeated major fluctuations in the carbonate record after 3.1 ka therefore most likely reflect the historical variation in hydrothermal inputs.

  18. Holocene carbonate record of Lake Kivu reflects the history of hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Votava, Jillian E.; Johnson, Thomas C.; Hecky, Robert E.

    2017-01-01

    The sediment record of Lake Kivu reveals a complex volcanogenic and climatic Holocene history. Investigation of the inorganic carbonate record dates the onset of carbonate deposition in the mid-Holocene in Kivu’s deep northern and eastern basins and identifies conditions enabling deposition. The magnitude and timing of carbonate-rich sedimentation is not so much controlled by climate but, instead, linked strongly to hydrothermal activity in the basin. Sublacustrine springs supply the vast majority of the calcium and carbonate ions required for supersaturation with respect to aragonite. This major hydrothermal activity that permanently stratifies Lake Kivu today was initiated ˜3,100 y before present (3.1 ka), when carbonate-rich sediments first appeared in the Holocene record. Aragonite is the dominant CaCO3 mineral present in the lake deposits. Both δ13C and δ18O of the aragonite are enriched above the expected kinetic fractionation of meteoric waters, suggesting a volcanogenic influence on the formation waters. Repeated major fluctuations in the carbonate record after 3.1 ka therefore most likely reflect the historical variation in hydrothermal inputs.

  19. The production of glucose from corn stalk using hydrothermal process with pre-treatment ultrasound assisted alkaline

    NASA Astrophysics Data System (ADS)

    Yolanda, Dora; Prasutiyo, Indry; Trisanti, P. N.; Sumarno

    2015-12-01

    The production of glucose from corn stalk by using subcritical hydrothermal technology is studied in this work. Ultrasound-assisted alkaline delignification methods are used as pre-treatment. The corn stalk powder were pretreated with ultrasound-assisted alkaline (NaOH 2% w/w, solid to liquid ratio 1:22 w/v) at room temperature and 30 minutes. After pre-treatment, solid residue and liquid fractions are separated by filtration. Pretreated solids are further submitted to hydrothermal process for glucose production. Hydrothermal process was carried out at 100 Bar and 120°C in various times. The solid product was characterized by SEM and XRD. And liquid product was analysis using DNS method to determine percentage of glucose. From XRD analysis showed that crystallinity of material was lower than delignification product.

  20. Volcanic and Hydrothermal Activity of the North Su Volcano: New Insights from Repeated Bathymetric Surveys and ROV Observations

    NASA Astrophysics Data System (ADS)

    Thal, J.; Bach, W.; Tivey, M.; Yoerger, D.

    2013-12-01

    Bathymetric data from cruises in 2002, 2006, and 2011 were combined and compared to determine the evolution of volcanic activity, seafloor structures, erosional features and to identify and document the distribution of hydrothermal vents on North Su volcano, SuSu Knolls, eastern Manus Basin (Papua New Guinea). Geologic mapping based on ROV observations from 2006 (WHOI Jason-2) and 2011 (MARUM Quest-4000) combined with repeated bathymetric surveys from 2002 and 2011 are used to identify morphologic features on the slopes of North Su and to track temporal changes. ROV MARUM Quest-4000 bathymetry was used to develop a 10 m grid of the top of North Su to precisely depict recent changes. In 2006, the south slope of North Su was steeply sloped and featured numerous white smoker vents discharging acid sulfate waters. These vents were covered by several tens of meters of sand- to gravel-sized volcanic material in 2011. The growth of this new cone changed the bathymetry of the south flank of North Su up to ~50 m and emplaced ~0.014 km3 of clastic volcanic material. This material is primarily comprised of fractured altered dacite and massive fresh dacite as well as crystals of opx, cpx, olivine and plagioclase. There is no evidence for pyroclastic fragmentation, so we hypothesize that the fragmentation is likely related to hydrothermal explosions. Hydrothermal activity varies over a short (~50 m) lateral distance from 'flashing' black smokers to acidic white smoker vents. Within 2 weeks of observation time in 2011, the white smoker vents varied markedly in activity suggesting a highly episodic hydrothermal system. Based on ROV video recordings, we identified steeply sloping (up to 30°) slopes exposing pillars and walls of hydrothermal cemented volcaniclastic material representing former fluid upflow zones. These features show that hydrothermal activity has increased slope stability as hydrothermal cementation has prevented slope collapse. Additionally, in some places

  1. Iron oxide nanoparticles embedded in activated carbons prepared from hydrothermally treated waste biomass.

    PubMed

    Hao, Wenming; Björkman, Eva; Yun, Yifeng; Lilliestråle, Malte; Hedin, Niklas

    2014-03-01

    Particles of iron oxide (Fe3O4 ; 20–40 nm) were embedded within activated carbons during the activation of hydrothermally carbonized (HTC) biomasses in a flow of CO2. Four different HTC biomass samples (horse manure, grass cuttings, beer production waste, and biosludge) were used as precursors for the activated carbons. Nanoparticles of iron oxide formed from iron catalyst included in the HTC biomasses. After systematic optimization, the activated carbons had specific surface areas of about 800 m2g1. The pore size distributions of the activated carbons depended strongly on the degree of carbonization of the precursors. Activated carbons prepared from highly carbonized precursors had mainly micropores, whereas those prepared from less carbonized precursors contained mainly mesopores. Given the strong magnetism of the activated carbon–nano-Fe3O4 composites, they could be particularly useful for water purification.

  2. Hydrothermal carbonization of biomass from landscape management - Influence of process parameters on soil properties of hydrochars.

    PubMed

    Röhrdanz, Michael; Rebling, Tammo; Ohlert, Jan; Jasper, Jan; Greve, Thomas; Buchwald, Rainer; von Frieling, Petra; Wark, Michael

    2016-05-15

    Besides pyrolysis the technology of hydrothermal carbonization (HTC) is tested to produce hydrochars for soil improvement. The chemical and physical properties of the hydrochars mainly depend on the feedstock and the process parameters reaction time and process temperature. Systematic investigations on the influences of these process parameters on soil properties of hydrochars like water holding capacity (WHC) and cation exchange capacity (CEC) are missing. In this study, a rush-rich biomass was carbonized within defined HTC process conditions under variation of reaction time and process temperature to produce hydrochars. Analysis of WHC, CEC, the elemental composition and Fourier-transform infrared spectroscopy (FT-IR) were performed to evaluate the influence of HTC process conditions on the pedological hydrochar properties. The results indicated that at increasing reaction severity (reaction time and process temperature) WHC and CEC decreased as well as the elemental O/C ratio. The decrease of WHC and CEC is based on the decrease of the hydrochar surface polarity. However, even the lowest WHC and CEC of investigated hydrochars still exceeded those of pure quartz sand by factors of 5-10. An application of hydrochars produced at severe HTC conditions could improve WHC and CEC of sandy soils. This has to be investigated in further studies.

  3. Surface Defects Control for ZnO Nanorods Synthesized Through a Gas-Assisted Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Zhao, Limin; Shu, Changhua; Jia, Zhengfeng; Wang, Changzheng

    2017-01-01

    Oxygen vacancies in crystal have an important impact on the electronic properties of zinc oxide (ZnO). In this paper, ZnO nanorods with rich oxygen vacancies were prepared through a novel gas-assisted hydrothermal growth process. X-ray diffraction data showed that single-phase ZnO with the wurtzite crystal structure was obtained and the crystallite size decreased as the reaction atmosphere pressure increased. The oxygen vacancies of ZnO were confirmed using x-ray photoelectron spectroscopy and photoluminescence spectroscopy. The results showed that the concentration of oxygen vacancies could be regulated by both the atmosphere pressure and the atmosphere properties. The oxygen vacancies in ZnO samples were reduced when the pressure increase in the hydrogen reaction environment (reducing atmosphere) and the oxygen vacancies in ZnO samples were increased when the pressure increased in the oxygen reaction environment (oxidizing atmosphere).

  4. Effects of processing conditions on biocrude yields from fast hydrothermal liquefaction of microalgae.

    PubMed

    Faeth, Julia L; Savage, Phillip E

    2016-04-01

    This study investigated the effects of algae species, reaction time, and reactor loading on the biocrude yield from fast hydrothermal liquefaction (HTL) of microalgae. Fast HTL reaction times were always less than 2 min and employed rapid heating and nonisothermal conditions. The highest biocrude yield obtained was 67±5 wt.% (dry basis). With all other process variables fixed, increasing the reaction time in a 600 °C sand bath by 15 s increments led to a rapid increase in biocrude yield between 15 and 45 s. At longer times, the biocrude yield decreased. Low reactor loadings generally gave higher biocrude yields than did higher loadings. The low reactor loadings may facilitate biocrude production by facilitating cell rupture and/or increasing the effective concentration of algal cells in the hot, compressed water in the reactor.

  5. Chicxulub Impact Melts: Geochemical Signatures of Target Lithology Mixing and Post-Impact Hydrothermal Fluid Processes

    NASA Technical Reports Server (NTRS)

    Kring, David A.; Zurcher, Lukas; Horz, Freidrich; Mertzmann, Stanley A.

    2004-01-01

    Impact melts within complex impact craters are generally homogeneous, unless they differentiated, contain immiscible melt components, or were hydrothermally altered while cooling. The details of these processes, however, and their chemical consequences, are poorly understood. The best opportunity to unravel them may lie with the Chicxulub impact structure, because it is the world s most pristine (albeit buried) large impact crater. The Chicxulub Scientific Drilling Project recovered approx. 100 meters of impactites in a continuous core from the Yaxcopoil-1 (YAX-1) borehole. This dramatically increased the amount of melt available for analyses, which was previously limited to two small samples N17 and N19) recovered from the Yucatan-6 (Y-6) borehole and one sample (N10) recovered from the Chicxulub-1 (C-1) borehole. In this study, we describe the chemical compositions of six melt samples over an approx. 40 m section of the core and compare them to previous melt samples from the Y-6 and C-1 boreholes.

  6. Electromagnetic Wave Shieding Effectiveness of Carbon Fiber Sheet Coated Ferrite Film by Microwave-Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Murakami, Ri Ichi; Yamamoto, Hidetoshi; Kim, Chan Kong; Yim, Cheol Mun; Kim, Yun Hae

    The developments of electromagnetic wave shielding materials are strongly required because the malfunction of electronic equipment, mobile phone and wireless LAN avoids. In this study, it was investigated that the electromagnetic shielding effectiveness of carbon fiber sheets were enhanced by the ferrite which was coated by the microwave hydrothermal process. For coated carbon fiber sheet, the effects of ferrite and lamination of carbon fiber textile on the electromagnetic wave shielding effectiveness were discussed. In the range of frequency (100 1 GHz), the electromagnetic wave shielding effectiveness was measured by using TEM-Cell. The electromagnetic wave shielding effectiveness was greater for the coated carbon fiber sheets than for the uncoated carbon fiber sheets. When the insulation film was located between two carbon fiber sheets, the electromagnetic wave shielding effectiveness increased.

  7. Response to"Analysis of the Treatment, by the U.S. Department of Energy, of the FEP Hydrothermal Activity in the Yucca Mountain Performance Assessment" by Yuri Dublyansky

    SciTech Connect

    Houseworth, J.E.; Hardin, E.

    2008-11-17

    This paper presents a rebuttal to Dublyansky (2007), which misrepresents technical issues associated with hydrothermal activity at the proposed Yucca Mountain nuclear waste repository and their importance to the long-term performance of the repository. In this paper, questions associated with hydrothermal activity are reviewed and the justification for exclusion of hydrothermal activity from performance assessment is presented. The hypothesis that hydrothermal upwelling into the present-day unsaturated zone has occurred at Yucca Mountain is refuted by the unambiguous evidence that secondary minerals and fluid inclusions in the unsaturated zone formed in an unsaturated environment from downward percolating meteoric waters. The thermal history at Yucca Mountain, inferred from fluid inclusion and isotopic data, is explained in terms of the tectonic extensional environment and associated silicic magmatism. The waning of tectonic extension over millions of years has led to the present-day heat flux in the Yucca Mountain region that is below average for the Great Basin. The long time scales of tectonic processes are such that any effects of a resumption of extension or silicic magmatism on hydrothermal activity at Yucca Mountain over the 10,000-year regulatory period would be negligible. The conclusion that hydrothermal activity was incorrectly excluded from performance assessment as asserted in Dublyansky (2007) is contradicted by the available technical and regulatory information.

  8. Effect of hydrothermal processing on carrot carotenoids changes and interactions with dietary fiber.

    PubMed

    Borowska, Julitta; Kowalska, Marta; Czaplicki, Sylwester; Zadernowski, Ryszard

    2003-02-01

    The aim of the studies was to determine the effect of different methods of heat treatment on carotenoids changes and their interactions with insoluble and soluble dietary fiber. Three industrial varieties of carrot--Simba, Caropak and Fayette constituted the experimental material. Carrot cubes were subjected to heat treatment by putting in water with or without citric acid, or in a convection-type steam furnace. The total content of alpha- and beta-carotene was determined in all kinds of pureed carrots. Its amount bounded with insoluble dietary fiber and pectins was also determined. Changes in soluble and insoluble fractions of dietary fiber during hydrothermal treatment were also determined. It was found that the content of trans alpha- and beta-carotene in carrots decreased significantly (p < 0.05) after heat treatment, compared with the control sample. The loss observed during heat treatment in water was higher (up to 50%) than in the case of a convection-type steam furnace. The highest decrease in the content of insoluble fraction of dietary fiber and the highest increase in soluble fraction were observed after treatment with the use of steam. An analysis of interactions between carotenoids and dietary fiber fractions after hydrothermal processing shows their stronger affinity to forming bonds with pectins than with insoluble fiber. It was also found that the effect of heat treatment parameters was significant--the highest (by six times) increase in the content of beta-carotene bounded with pectins was noted in pureed carrots processed in a convection-type steam furnace.

  9. Use of soft hydrothermal processing to improve and recycle bedding for laboratory animals.

    PubMed

    Miyamoto, T; Li, Z; Kibushi, T; Yamasaki, N; Kasai, N

    2008-10-01

    Cage bedding for laboratory rodents can influence animal wellbeing and thus the experimental data. In addition, a large amount of used bedding containing excrement is discharged as medical waste from life science institutes and breeding companies. We developed a ground-breaking system to improve fresh bedding and recycle used bedding by applying a soft hydrothermal process with high-temperature and high-pressure dry steam. The system removes both harmful organic components and aromatic hydrocarbons that can affect animals' metabolism. The purpose of the present study was to evaluate the chemical and physical properties of the improved fresh bedding and the recycled used bedding treated by the system. The results showed that 68-99% of the predominant aromatic hydrocarbons were removed from fresh bedding treated at 0.35 MPa and 140 degrees C for 120 min ('improved bedding'). In addition, 59.4-99.0% of predominant harmful organic compounds derived from excrement were removed from used bedding treated at 0.45 MPa and 150 degrees C for 60 min ('recycled bedding'). The soft hydrothermal treatment increased the number of acidic functional groups on the bedding surface and gave it the high adsorptive efficiency of ammonia gas. Harmful substances such as microorganisms, heavy metals and pesticides decreased below the detection limit. The results clearly showed that the improved and recycled bedding is safer for laboratory rodents and has the potential to ameliorate conditions in primary and secondary enclosures (e.g. cages and animal rooms) used for maintaining laboratory animals. This process may be one of the most advanced techniques in providing an alternative to softwood and other bedding, economizing through the recycling of used bedding and reducing bedding waste from animal facilities.

  10. Mineralogical and geochemical evidence for hydrothermal activity at the west wall of 12°50′N core complex (Mid-Atlantic ridge): a new ultramafic-hosted seafloor hydrothermal deposit?

    USGS Publications Warehouse

    Dekov, Vesselin; Boycheva, Tanya; Halenius, Ulf; Billstrom, Kjell; Kamenov, George D.; Shanks, Wayne C.; Stummeyer, Jens

    2011-01-01

    Dredging along the west wall of the core complex at 12°50′N Mid-Atlantic Ridge sampled a number of black oxyhydroxide crusts and breccias cemented by black and dark brown oxyhydroxide matrix. Black crusts found on top of basalt clasts (rubble) are mainly composed of Mn-oxides (birnessite, 10-Å manganates) with thin films of nontronite and X-ray amorphous FeOOH on their surfaces. Their chemical composition (low trace- and rare earth-element contents, high Li and Ag concentrations, rare earth element distribution patterns with negative both Ce and Eu anomalies), Sr–Nd–Pb-isotope systematic and O-isotope data suggest low-temperature (~ 20 °C) hydrothermal deposition from a diffuse vent area on the seafloor. Mineralogical, petrographic and geochemical investigations of the breccias showed the rock clasts were hydrothermally altered fragments of MORBs. Despite the substantial mineralogical changes caused by the alteration the Sr–Nd–Pb-isotope ratios have not been significantly affected by this process. The basalt clasts are cemented by dark brown and black matrix. Dark brown cement exhibits geochemical features (very low trace- and rare earth- element contents, high U concentration, rare earth element distribution pattern with high positive Eu anomaly) and Nd–Pb-isotope systematics (similar to that of MORB) suggesting that the precursor was a primary, high-temperature Fe-sulfide, which was eventually altered to goethite at ambient seawater conditions. The data presented in this work points towards the possible existence of high- and low-temperature hydrothermal activity at the west wall of the core complex at 12°50′N Mid-Atlantic Ridge. Tectonic setting at the site implies that the proposed hydrothermal field is possibly ultramafic-hosted.

  11. Cultivation of a microalga Chlorella vulgaris using recycled aqueous phase nutrients from hydrothermal carbonization process.

    PubMed

    Du, Zhenyi; Hu, Bing; Shi, Aimin; Ma, Xiaochen; Cheng, Yanling; Chen, Paul; Liu, Yuhuan; Lin, Xiangyang; Ruan, Roger

    2012-12-01

    This study investigated the feasibility of using recovered nutrients from hydrothermal carbonization (HTC) for cultivation of microalga Chlorella vulgaris. Different dilution multiples of 50, 100 and 200 were applied to the recycled process water from HTC and algal growth was compared among these media and a standard growth medium BG-11. Algae achieved a biomass concentration of 0.79 g/L on 50 × process water after 4 days. Algae removed total nitrogen, total phosphorus and chemical oxygen demand by 45.5-59.9%, 85.8-94.6% and 50.0-60.9%, respectively, on differently diluted process water. The fatty acid methyl ester yields for algae grown on the process water were 11.2% (50 ×), 11.2% (100 ×) and 9.7% (200 ×), which were significantly higher than 4.5% for BG-11. In addition, algae cultivated on process water had 18.9% higher carbon and 7.8% lower nitrogen contents than those on BG-11, indicating that they are very suitable as biofuel feedstocks.

  12. Fundamental chemistry and thermodynamics of hydrothermal oxidation processes. 1998 annual progress report

    SciTech Connect

    Simonson, J.M.; Mesmer, R.E.; Blencoe, J.G.; Cummings, P.T.; Chialvo, A.A.

    1998-06-01

    'The objective of this research program is to provide fundamental scientific information on the physical and chemical properties of solutes in aqueous solutions at high temperatures needed to assess and enhance the applicability of hydrothermal oxidation (HTO) to the remediation of DOE hazardous and mixed wastes. Potential limitations to the use of HTO technology include formation of deposits (scale) from precipitation of inorganic solutes in the waste, corrosion arising from formation of strong acids on oxidation of some organic compounds (e.g., chlorinated hydrocarbons), and unknown effects of fluid density and phase behavior at high temperatures. Focus areas for this project include measurements of the solubility and speciation of actinides and surrogates in model HTO process streams at high temperatures, and the experimental and theoretical development of equations of state for aqueous mixtures under HTO process conditions ranging above the critical temperature of water. A predictive level of understanding of the chemical and physical properties of HTO process streams is being developed through molecular-level simulations of aqueous solutions at high temperatures. Advances in fundamental understanding of phase behavior, density, and solute speciation at high temperatures and pressures contribute directly to the ultimate applicability of this process for the treatment of DOE hazardous and mixed wastes. Research in this project has been divided into individual tasks, with each contributing to a unified understanding of HTO processing problems related to the treatment of DOE wastes. This report summarizes progress attained after slightly less than two years of this three-year project.'

  13. Structural elucidation of sorghum lignins from an integrated biorefinery process based on hydrothermal and alkaline treatments.

    PubMed

    Sun, Shao-Long; Wen, Jia-Long; Ma, Ming-Guo; Sun, Run-Cang

    2014-08-13

    An integrated process based on hydrothermal pretreatment (HTP) (i.e., 110-230 °C, 0.5-2.0 h) and alkaline post-treatment (2% NaOH at 90 °C for 2.0 h) has been performed for the production of xylooligosaccharide, lignin, and digestible substrate from sweet sorghum stems. The yield, purity, dissociation mechanisms, structural features, and structural transformations of alkali lignins obtained from the integrated process were investigated. It was found that the HTP process facilitated the subsequent alkaline delignification, releasing lignin with the highest yield (79.3%) and purity from the HTP residue obtained at 190 °C for 0.5 h. All of the results indicated that the cleavage of the β-O-4 linkages and degradation of β-β and β-5 linkages occurred under the harsh HTP conditions. Depolymerization and condensation reactions simultaneously occurred at higher temperatures (≥ 170 °C). Moreover, the thermostability of lignin was positively related to its molecular weight, but was also affected by the inherent structures, such as β-O-4 linkages and condensed units. These findings will enhance the understanding of structural transformations of the lignins during the integrated process and maximize the potential utilizations of the lignins in a current biorefinery process.

  14. Hydrothermal Synthesis of Ultrasmall Pt Nanoparticles as Highly Active Electrocatalysts for Methanol Oxidation

    PubMed Central

    Ji, Wenhai; Qi, Weihong; Tang, Shasha; Peng, Hongcheng; Li, Siqi

    2015-01-01

    Ultrasmall nanoparticles, with sizes in the 1–3 nm range, exhibit unique properties distinct from those of free molecules and larger-sized nanoparticles. Demonstrating that the hydrothermal method can serve as a facile method for the synthesis of platinum nanoparticles, we successfully synthesized ultrasmall Pt nanoparticles with an average size of 2.45 nm, with the aid of poly(vinyl pyrrolidone) (PVP) as reducing agents and capping agents. Because of the size effect, these ultrasmall Pt nanoparticles exhibit a high activity toward the methanol oxidation reaction.

  15. Discovery of hydrothermally active and extinct talc mounds on the Mid-Cayman Rise

    NASA Astrophysics Data System (ADS)

    Hodgkinson, M.; Murton, B. J.; Roberts, S.

    2013-12-01

    Since 1977, hydrothermal vents have been the subject of intense scientific interest due to their role in cooling the oceanic crust and global geochemical cycles. Until now, two types of hydrothermal system have been identified: one, driven by magmatic heat extruding ';black smoker' fluids; and another, involving serpentinisation of ultramafic rocks and the precipitation of carbonate/brucite chimneys. Here, we present details of a new, off-axis type of hydrothermal system consisting of mounds of predominately botryoidal talc (a magnesium-silicate) with accessory silica and copper sulphides, and chimneys exhaling fluids of moderate temperature and pH. Discovered on the Mid-Cayman Rise (MCR) in 2010, the Von Damm Vent Field (VDVF) features a NNW-ESE-trending line of four overlapping cones, the largest of which is 75 m high by 150 m in diameter. The VDVF is hosted in the gabbroic footwall of the Mount Dent Oceanic Core Complex (MDOCC), which includes serpentinised peridotite at depth. The largest cone vents clear fluids from two main orifices at its summit, with primary temperatures of 215°C. Elsewhere, both focussed and diffuse flow areas emit fluids with temperatures of up to 150°C. The surrounding ~1 m thick pelagic sediment contains abundant pockmarks that emit methane-rich fluids at temperatures of less than 10°C. During the return to the MCR in early 2013, several other talc mounds were discovered within a kilometre of the active VDVF. These inactive mounds also comprise an assemblage of botryoidal talc, silica, disseminated sulphides (including chalcopyrite) and sulphates. One of these mounds (Mystic Mount) is double the volume of the active VDVF. The unique dominance of talc as the major mineral forming the hydrothermal structures indicates unusual vent fluid compositions that are able to carry both copper (at high-temperatures) and precipitate magnesium silicate. Thermodynamic modelling indicates that talc precipitates on mixing a moderately acidic, silica

  16. Xenopumice erupted on 15 October 2011 offshore of El Hierro (Canary Islands): a subvolcanic snapshot of magmatic, hydrothermal and pyrometamorphic processes

    NASA Astrophysics Data System (ADS)

    Del Moro, S.; Di Roberto, A.; Meletlidis, S.; Pompilio, M.; Bertagnini, A.; Agostini, S.; Ridolfi, F.; Renzulli, A.

    2015-06-01

    On 15 October 2011, a submarine eruption offshore of El Hierro Island gave rise to floating volcanic products, known as xenopumices, i.e., pumiceous xenoliths partly mingled and coated with the juvenile basanitic magma. Over the last few years, no consensus in the scientific community in explaining the origin of these products has been reached. In order to better understand the formation of xenopumice, we present a textural, mineralogical, and geochemical study of the possible magmatic, hydrothermal, and pyrometamorphic processes, which usually operate in the plumbing systems of active volcanoes. We carried out a comprehensive SEM investigation and Sr-Nd-Pb isotope analyses on some samples representative of three different xenopumice facies. All the data were compared with previous studies, new data for El Hierro extrusives and a literature dataset of Canary Islands igneous and sedimentary rocks. In the investigated xenopumices, we emphasize the presence of restitic magmatic phases as well as crystallization of minerals (mainly olivine + pyroxene + magnetite aggregates) as pseudomorphs after pre-existing mafic phenocrysts, providing evidence of pyrometamorphism induced by the high-T juvenile basanitic magma. In addition, we identify veins consisting of zircon + REE-oxides + mullite associated with Si-rich glass and hydrothermal quartz, which indicate the fundamental role played by hydrothermal fluid circulation in the xenopumice protolith. The petrological data agree with a pre-syneruptive formation of the xenopumice, when El Hierro basanite magma intruded hydrothermally altered trachyandesite to trachyte rocks and triggered local partial melting. Therefore, the El Hierro xenopumice represents a snapshot of the transient processes at the magma-wall rock interface, which normally occurs in the feeding system of active volcanoes.

  17. Living with the Heat. Submarine Ring of Fire--Grades 5-6. Hydrothermal Vent Ecology.

    ERIC Educational Resources Information Center

    National Oceanic and Atmospheric Administration (DOC), Rockville, MD.

    This activity is designed to teach about hydrothermal vent ecology. Students are expected to describe how hydrothermal vents are formed and characterize the physical conditions at these sites, explain chemosynthesis and contrast this process with photosynthesis, identify autotrophic bacteria as the basis for food webs in hydrothermal vent…

  18. Record of archaeal activity at the serpentinite-hosted Lost City Hydrothermal Field.

    PubMed

    Méhay, S; Früh-Green, G L; Lang, S Q; Bernasconi, S M; Brazelton, W J; Schrenk, M O; Schaeffer, P; Adam, P

    2013-11-01

    Samples of young, outer surfaces of brucite-carbonate deposits from the ultramafic-hosted Lost City hydrothermal field were analyzed for DNA and lipid biomarker distributions and for carbon and hydrogen stable isotope compositions of the lipids. Methane-cycling archaeal communities, notably the Lost City Methanosarcinales (LCMS) phylotype, are specifically addressed. Lost City is unlike all other hydrothermal systems known to date and is characterized by metal- and CO2 -poor, high pH fluids with high H2 and CH4 contents resulting from serpentinization processes at depth. The archaeal fraction of the microbial community varies widely within the Lost City chimneys, from 1-81% and covaries with concentrations of hydrogen within the fluids. Archaeal lipids include isoprenoid glycerol di- and tetraethers and C25 and C30 isoprenoid hydrocarbons (pentamethylicosane derivatives - PMIs - and squalenoids). In particular, unsaturated PMIs and squalenoids, attributed to the LCMS archaea, were identified for the first time in the carbonate deposits at Lost City and probably record processes exclusively occurring at the surface of the chimneys. The carbon isotope compositions of PMIs and squalenoids are remarkably heterogeneous across samples and show highly (13) C-enriched signatures reaching δ(13) C values of up to +24.6‰. Unlike other environments in which similar structural and isotopic lipid heterogeneity has been observed and attributed to diversity in the archaeal assemblage, the lipids here appear to be synthesized solely by the LCMS. Some of the variations in lipid isotope signatures may, in part, be due to unusual isotopic fractionation during biosynthesis under extreme conditions. However, we argue that the diversity in archaeal abundances, lipid structure and carbon isotope composition rather reflects the ability of the LCMS archaeal biofilms to adapt to chemical gradients in the hydrothermal chimneys and possibly to perform either methanotrophy or methanogenesis

  19. Key Factors Influencing Rates of Heterotrophic Sulfate Reduction in Active Seafloor Hydrothermal Massive Sulfide Deposits

    PubMed Central

    Frank, Kiana L.; Rogers, Karyn L.; Rogers, Daniel R.; Johnston, David T.; Girguis, Peter R.

    2015-01-01

    Hydrothermal vents are thermally and geochemically dynamic habitats, and the organisms therein are subject to steep gradients in temperature and chemistry. To date, the influence of these environmental dynamics on microbial sulfate reduction has not been well constrained. Here, via multivariate experiments, we evaluate the effects of key environmental variables (temperature, pH, H2S, SO42−, DOC) on sulfate reduction rates and metabolic energy yields in material recovered from a hydrothermal flange from the Grotto edifice in the Main Endeavor Field, Juan de Fuca Ridge. Sulfate reduction was measured in batch reactions across a range of physico-chemical conditions. Temperature and pH were the strongest stimuli, and maximum sulfate reduction rates were observed at 50°C and pH 6, suggesting that the in situ community of sulfate-reducing organisms in Grotto flanges may be most active in a slightly acidic and moderate thermal/chemical regime. At pH 4, sulfate reduction rates increased with sulfide concentrations most likely due to the mitigation of metal toxicity. While substrate concentrations also influenced sulfate reduction rates, energy-rich conditions muted the effect of metabolic energetics on sulfate reduction rates. We posit that variability in sulfate reduction rates reflect the response of the active microbial consortia to environmental constraints on in situ microbial physiology, toxicity, and the type and extent of energy limitation. These experiments help to constrain models of the spatial contribution of heterotrophic sulfate reduction within the complex gradients inherent to seafloor hydrothermal deposits. PMID:26733984

  20. Ore-bearing hydrothermal metasomatic processes in the Elbrus volcanic center, the northern Caucasus, Russia

    NASA Astrophysics Data System (ADS)

    Gurbanov, A. G.; Bogatikov, O. A.; Dokuchaev, A. Ya.; Gazeev, V. M.; Abramov, S. S.; Groznova, E. O.; Shevchenko, A. V.

    2008-06-01

    Precaldera, caldera, and postcaldera cycles are recognized in the geological evolution of the Pleistocene-Holocene Elbrus volcanic center (EVC). During the caldera cycle, the magmatic activity was not intense, whereas hydrothermal metasomatic alteration of rocks was vigorous and extensive. The Kyukyurtli and Irik ore-magmatic systems have been revealed in the EVC, with the former being regarded as the more promising one. The ore mineralization in rocks of the caldera cycle comprises occurrences of magnetite, ilmenite, pyrite and pyrrhotite (including Ni-Co varieties), arsenopyrite, chalcopyrite, millerite, galena, and finely dispersed particles of native copper. Pyrite and pyrrhotite from volcanics of the caldera cycle and dacite of the Kyukyurtli extrusion are similar in composition and differ from these minerals of the postcaldera cycle, where pyrite and pyrrhotite are often enriched in Cu, Co, and Ni and millerite is noted as well. The composition of ore minerals indicates that the hydrothermal metasomatic alteration related to the evolution of the Kyukyurtli hydrothermal system was superimposed on rocks of the caldera cycle, whereas the late mineralization in rocks of the postcaldera cycle developed autonomously. The homogenization temperature of fluid inclusions in quartz and carbonate from crosscutting veinlets in the apical portion of the Kyukyurtli extrusion is 140-170°C and in quartz from geyserite, 120-150°C. The temperature of formation of the chalcopyrite-pyrite-pyrrhotite assemblage calculated using mineral geothermometers is 156 and 275°C in dacite from the middle and lower portions of the Malka lava flow and 190°C in dacite of the Kyukyurtli extrusion. The hydrothermal solutions that participated in metasomatic alteration of rocks pertaining to the Kyukyurtli ore-magmatic system (KOMS) and formed both secondary quartzite and geyserite were enriched in fluorine, as evidenced from the occurrence of F-bearing minerals-zharchikhite, ralstonite,

  1. Green synthesis of silver nanoparticles in aloe vera plant extract prepared by a hydrothermal method and their synergistic antibacterial activity

    PubMed Central

    Phromviyo, Nutthakritta; Boueroy, Parichart; Chompoosor, Apiwat

    2016-01-01

    Background There is worldwide interest in silver nanoparticles (AgNPs) synthesized by various chemical reactions for use in applications exploiting their antibacterial activity, even though these processes exhibit a broad range of toxicity in vertebrates and invertebrates alike. To avoid the chemical toxicity, biosynthesis (green synthesis) of metal nanoparticles is proposed as a cost-effective and environmental friendly alternative. Aloe vera leaf extract is a medicinal agent with multiple properties including an antibacterial effect. Moreover the constituents of aloe vera leaves include lignin, hemicellulose, and pectins which can be used in the reduction of silver ions to produce as AgNPs@aloe vera (AgNPs@AV) with antibacterial activity. Methods AgNPs were prepared by an eco-friendly hydrothermal method using an aloe vera plant extract solution as both a reducing and stabilizing agent. AgNPs@AV were characterized using XRD and SEM. Additionally, an agar well diffusion method was used to screen for antimicrobial activity. MIC and MBC were used to correlate the concentration of AgNPs@AV its bactericidal effect. SEM was used to investigate bacterial inactivation. Then the toxicity with human cells was investigated using an MTT assay. Results The synthesized AgNPs were crystalline with sizes of 70.70 ± 22-192.02 ± 53 nm as revealed using XRD and SEM. The sizes of AgNPs can be varied through alteration of times and temperatures used in their synthesis. These AgNPs were investigated for potential use as an antibacterial agent to inhibit pathogenic bacteria. Their antibacterial activity was tested on S. epidermidis and P. aeruginosa. The results showed that AgNPs had a high antibacterial which depended on their synthesis conditions, particularly when processed at 100 oC for 6 h and 200 oC for 12 h. The cytotoxicity of AgNPs was determined using human PBMCs revealing no obvious cytotoxicity. These results indicated that AgNPs@AV can be effectively utilized in

  2. Aqueous Volatiles in Hydrothermal fluids from the Main Endeavour Vent Field: Temporal Variability Following Earthquake Activity

    NASA Astrophysics Data System (ADS)

    Seewald, J. S.; Cruse, A. M.; Saccocia, P. J.

    2001-12-01

    Volatile species play a critical role in a broad spectrum of physical, chemical, and biological processes associated with hydrothermal circulation at oceanic spreading centers. Earthquake activity at the Main Endeavour vent field, northern Juan de Fuca Ridge in June 1999 [1] provided and opportunity to assess factors that regulate the flux of volatile species from the oceanic crust to the water column following a rapid change in subsurface reaction zone conditions. High temperature vent fluids were collected in gas-tight samplers at the Main Endeavour field in September 1999, approximately four months after the earthquakes, and again in July 2000, and were analyzed for the abundance of aqueous volatile and non-volatile species. Measured concentrations of aqueous H2, H2S, and CO2 increased substantially in September 1999 relative to pre-earthquake values [2,3], and subsequently decreased in July 2000, while aqueous Cl concentrations initially decreased in 1999 and subsequently increased in 2000. Concentrations of Cl in all fluids were depleted relative to seawater values. Aqueous CH4 and NH3 concentrations decreased in both the 1999 and 2000 samples relative to pre- earthquake values. Variations in Cl concentration of Endeavour fluids reflect varying degrees of phase separation under near critical temperature and pressure conditions. Because volatile species efficiently partition into the vapor phase, variations in their abundance as a function of Cl concentration can be used to constrain conditions of phase separation and fluid-rock interaction. For example, concentrations of volatile species that are not readily incorporated into minerals (CH4 and NH3) correlated weakly with Cl suggesting phase separation was occurring under supercritical conditions after the earthquake activity. In contrast, compositional data for fluids prior to the earthquakes indicate a strong negative correlation between these species and Cl suggesting phase separation under subcritical

  3. Removal of strontium and transuranics from Hanford waste via hydrothermal processing -- FY 1994/95 test results

    SciTech Connect

    Orth, R.J.; Schmidt, A.J.; Elmore, M.R.; Hart, T.R.; Neuenschwander, G.G.; Gano, S.R.; Lehmann, R.W.; Momont, J.A.

    1995-09-01

    Under the Tank Waste Remediation System (TWRS) Pretreatment Technology Development Project, Pacific Northwest Laboratory (PNL) is evaluating and developing organic destruction technologies that may be incorporated into the Initial Pretreatment Module (IPM) to treat Hanford tank waste. Organic (and ferrocyanide) destruction removes the compounds responsible for waste safety issues, and conditions the supernatant for low-level waste disposal by removing compounds that may be responsible for promoting strontium and transuranic (TRU) components solubility. Destruction or defunctionalization of complexing organics in tank wastes eliminates organic species that can reduce the efficiency of radionuclide (E.g., {sup 90}Sr) separation processes, such as ion exchange, solvent extraction, and precipitation. The technologies being evaluated and tested for organic destruction are low-temperature hydrothermal processing (HTP) and wet air oxidation (WAO). Four activities are described: Batch HTP/WAO testing with Actual Tank Waste (Section 3.0), Batch HTP Testing with Simulant (Section 4.0), Batch WAO testing with Simulant (Section 5.0), and Continuous Bench-scale WAO Testing with Simulant (Section 6.0). For each of these activities, the objectives, test approach, results, status, and direction of future investigations are discussed. The background and history of the HTP/WAO technology is summarized below. Conclusions and Recommendations are provided in Section 2.0. A continuous HTP off-gas safety evaluation conducted in FY 1994 is included as Appendix A.

  4. Effect of hydrothermal processing on total polyphenolics and antioxidant potential of underutilized leafy vegetables, Boerhaavia diffusa and Portulaca oleracea

    PubMed Central

    Nagarani, Gunasekaran; Abirami, Arumugam; Nikitha, Prasad; Siddhuraju, Perumal

    2014-01-01

    Objective To investigate the effect of different processing methods on antioxidant properties of acetone extract of aerial parts from Boerhaavia diffusa and Portulaca oleracea. Methods The total phenolic and flavonoid contents were determined by Folin-Ciocalteau and aluminum chloride method, respectively. FRAP, metal chelating activity, DPPH, ABTS, nitric oxide, hydroxyl and superoxide radical scavenging activities, carotene/linoleic acid bleaching activity were used for the determination of antioxidant capacity. Results The total phenolics in Boerhaavia diffusa (82.79-162.80 mg GAE/g extract) were found to be higher when compared to that of Portulaca oleracea (22.94-10.02 mg GAE/g extract). Hydrothermal processing enhanced the level of inhibition on synthetic radicals such as DPPH (3 439-309 549 mmol TE/g extract) and ABTS (17 808-53 818 mmol TE/g extract) as well as biologically relevant radicals such as superoxide anion (70%-90%) and nitric oxide (49%-57%). In addition, boiling of the vegetables were found to be maximum capacity of FRAP (6 404.95 mmol Fe (II)/g extract) and metal chelating activity (1.53 mg EDTA/g extract) than the respective raw samples. Conclusions The present investigation suggests that the processing enhance the functionality and improves the availability of bioactive substances of these vegetables. In addition, they also exhibited more potent antioxidant activity. Therefore these natural weeds from the crop land ecosystem could be suggested as cost effective indigenous green vegetables for human diet and potential feed resources for animals. Further extensive studies on role and importance of those weeds in sustaining the agro biodiversity are also needed. PMID:25183131

  5. Older Shallow Hydrothermal Activity Along the North Edge of the Yellowstone Caldera

    NASA Astrophysics Data System (ADS)

    Larson, P. B.; Cosca, M.; Takeuchi, A.; Yano, R.

    2006-12-01

    The Grand Canyon of the Yellowstone River, Yellowstone Park, is incised into more than 300 vertical meters of hydrothermally altered post-caldera rhyolites (Tuff of Sulfur Creek and Canyon Flow, 480 ka). The alteration was produced by older hydrothermal activity that predates cutting of the canyon (latest Pleistocene?), not by the modern hot springs. The Seven Mile Hole area, in the canyon about 5 km below the lower falls of the Yellowstone River and located along the north edge of the caldera, is pervasively altered in the canyon walls north of the river. Two alteration assemblages have been found along and just below the modern rim that was very near the paleo-surface and exposes paleo-hot spring sinter, 1. Illite-silica (quartz and/or opal)-pyrite, and, 2. kaolinite-alunite-silica (quartz and/or opal)-pyrite. Quartz-sulfide veins and quartz and/or opal space fillings crosscut both assemblages. The alteration grades downward to pervasive vuggy silicification (quartz) with illite and disseminated pyrite, about 100 to 200 m below the canyon rim. One alunite sample yields an Ar-Ar age of 138 ka. Preliminary O isotope ratios for silica (quartz) space fillings associated with the alunite alteration range from 2.0 to -2.2 per mil. The mineral assemblages indicate that both acid-sulfate and alkali-chloride hydrothermal fluids altered the rocks in the Seven Mile Hole area. The silica O ratios suggest that the near- surface fluid had an O ratio less than -15 per mil. Projecting this fluid to depth along the hydrostatic boiling curve, accounting for batch steam separation, and ignoring near-surface mixing with shallow local meteoric groundwater, suggest a deep reservoir fluid O ratio less than -20 per mil. The Ar-Ar age shows that the hydrothermal system in this area of the Yellowstone caldera, located near and along the northern caldera wall, has been active for at least 138 ka, and may extend as far back as the age of the Tuff of Sulfur Creek at 480 ka.

  6. Enhanced hydrothermal activity along the East Pacific Rise during the last two glacial terminations

    NASA Astrophysics Data System (ADS)

    Lund, D. C.; Asimow, P. D.; Farley, K. A.

    2015-12-01

    Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Scaling estimates [1-2] and model results [3-4] indicate that glacial-interglacial changes in sea level should modulate melt production at mid-ocean ridges, an idea that has been confirmed with detailed surveys of ridge bathymetry [4-5]. The nature and timing of associated changes in hydrothermal activity have remained unknown, however, precluding a clear understanding of whether ridge magmatism can act as a negative feedback on ice sheet size. Here we present multiple records of hydrothermal sedimentation spanning 1300 km of the East Pacific Rise (EPR). At each location, the flux of Fe, Mn, and As increased beginning at ~25 kyr BP, reached maximum values by 15 kyr BP, and then decreased into the Holocene. Lateral sediment focusing is an unlikely explanation given the similar signal in multiple cores and the lack of evidence for anomalous horizontal transport in 3He-based focusing factors. Coherent variations in Fe, Mn, and As suggest that diagenetic overprinting is not the primary driver of the down core signal. Elevated metal fluxes also occur during Termination II. The time series of hydrothermal sedimentation bear a strong resemblance to a record of seafloor bathymetry from 17ºS [5], suggesting that both have a common driver. The simplest explanation is glacial-interglacial variations in sea level, which apparently modulates sub-ridge melting, seafloor bathymetry, and hydrothermal activity at the EPR. Our results imply that geothermal heat flux from ridges increases during the last two glacial terminations, which should act to erode the deep ocean stratification, enhance the abyssal circulation, and transmit excess heat to the Southern Ocean, thereby setting the stage for deglaciation. [1] Lund and Asimow (2008) AGU Fall Meeting, Abstract #PP11D-08. [2] Huybers and Langmuir (2009) Earth and Planetary Science Letters 286, 479-491. [3] Lund and Asimow (2011

  7. Synthesis of ZnO nanorod–nanosheet composite via facile hydrothermal method and their photocatalytic activities under visible-light irradiation

    SciTech Connect

    Tan, Wai Kian; Abdul Razak, Khairunisak; Lockman, Zainovia; Kawamura, Go; Muto, Hiroyuki; Matsuda, Atsunori

    2014-03-15

    ZnO composite films consisting of ZnO nanorods and nanosheets were prepared by low-temperature hydrothermal processing at 80 °C on seeded glass substrates. The seed layer was coated on glass substrates by sol–gel dip-coating and pre-heated at 300 °C for 10 min prior to hydrothermal growth. The size of the grain formed after pre-heat treatment was ∼40 nm. A preferred orientation seed layer at the c-axis was obtained, which promoted vertical growth of the ZnO nanorod arrays and formation of the ZnO nanosheets. X-ray diffraction patterns and high-resolution transmission electron microscope (HR-TEM) images confirmed that the ZnO nanorods and nanosheets consist of single crystalline and polycrystalline structures, respectively. Room temperature photoluminescence spectra of the ZnO nanorod–nanosheet composite films exhibited band-edge ultraviolet (UV) and visible emission (blue and green) indicating the formation of ZnO crystals with good crystallinity and are supported by Raman scattering results. The formation of one-dimensional (1D) ZnO nanorod arrays and two-dimensional (2D) ZnO nanosheet films using seeded substrates in a single low-temperature hydrothermal step would be beneficial for realization of device applications that utilize substrates with limited temperature stability. The ZnO nanorods and nanosheets composite structure demonstrated higher photocatalytic activity during degradation of aqueous methylene blue under visible-light irradiation. -- Graphical abstract: Schematic illustration of ZnO nanorod–nanosheet composite structure formation by hydrothermal at low-temperature of 80 °C against time. Highlights: • Novel simultaneous formation of ZnO nanorods and nanosheets composite structure. • Facile single hydrothermal step formation at low-temperature. • Photoluminescence showed ultraviolet and visible emission. • Feasible application on substrates with low temperature stability. • Improved photocatalytic activity under visible

  8. Functional carbonaceous materials from hydrothermal carbonization of biomass: an effective chemical process.

    PubMed

    Hu, Bo; Yu, Shu-Hong; Wang, Kan; Liu, Lei; Xu, Xue-Wei

    2008-10-28

    Recently, much attention has been attracted to the use of biomass to produce functional carbonaceous materials from the viewpoint of economic, environmental and societal issues. Among different techniques, the hydrothermal carbonization (HTC) process, a traditional but recently revived method, presents superior characteristics that make it a promising route of wide potential application. This perspective gives an overview of the latest advances in the HTC process of functional carbonaceous materials from biomass. First, we discuss the preparation of carbonaceous materials synthesized by the use of either highly directed or catalyst/template-assisted methods, from crude plant materials and carbohydrates respectively. These carbonaceous materials not only have special morphologies, such as nanospheres, nanocables, nanofibers, submicrocables, submicrotubes and porous structures, but also contain rich functional groups which can greatly improve hydrophilicity and chemical reactivity. Further, a general look is cast on the applications of this kind of carbonaceous materials in environmental, catalytic and electrical areas. Recent advances have demonstrated that the HTC process from biomass can provide promising methods for the rational design of a rich family of carbonaceous and hybrid functional carbon materials with important applications.

  9. Mass transfer constraints on the chemical evolution of an active hydrothermal system, Valles caldera, New Mexico

    USGS Publications Warehouse

    White, A.F.; Chuma, N.J.; Goff, F.

    1992-01-01

    Partial equilibrium conditions occur between fluids and secondary minerals in the Valles hydrothermal system, contained principally in the Tertiary rhyolitic Bandelier Tuff. The mass transfer processes are governed by reactive phase compositions, surface areas, water-rock ratios, reaction rates, and fluid residence times. Experimental dissolution of the vitric phase of the tuff was congruent with respect to Cl in the solid and produced reaction rates which obeyed a general Arrhenius release rate between 250 and 300??C. The 18O differences between reacted and unreacted rock and fluids, and mass balances calculations involving Cl in the glass phase, produced comparable water-rock ratios of unity, confirming the importance of irreversible reaction of the vitric tuff. A fluid residence time of approximately 2 ?? 103 years, determined from fluid reservoir volume and discharge rates, is less than 0.2% of the total age of the hydrothermal system and denotes a geochemically and isotopically open system. Mass transfer calculations generally replicated observed reservoir pH, Pco2, and PO2 conditions, cation concentrations, and the secondary mineral assemblage between 250 and 300??C. The only extraneous component required to maintain observed calcite saturation and high Pco2 pressures was carbon presumably derived from underlying Paleozoic limestones. Phase rule constraints indicate that Cl was the only incompatible aqueous component not controlled by mineral equilibrium. Concentrations of Cl in the reservoir directly reflect mass transport rates as evidenced by correlations between anomalously high Cl concentrations in the fluids and tuff in the Valles caldera relative to other hydrothermal systems in rhyolitic rocks. ?? 1992.

  10. Extensive hydrothermal activity revealed by multi-tracer survey in the Wallis and Futuna region (SW Pacific)

    NASA Astrophysics Data System (ADS)

    Konn, C.; Fourré, E.; Jean-Baptiste, P.; Donval, J. P.; Guyader, V.; Birot, D.; Alix, A. S.; Gaillot, A.; Perez, F.; Dapoigny, A.; Pelleter, E.; Resing, J. A.; Charlou, J. L.; Fouquet, Y.

    2016-10-01

    The study area is close to the Wallis and Futuna Islands in the French EEZ. It exists on the western boundary of the fastest tectonic area in the world at the junction of the Lau and North-Fiji basins. At this place, the unstable back-arc accommodates the plate motion in three ways: (i) the north Fiji transform fault, (ii) numerous unstable spreading ridges, and (iii) large areas of recent volcanic activity. This instability creates bountiful opportunity for hydrothermal discharge to occur. Based on geochemical (CH4, TDM, 3He) and geophysical (nephelometry) tracer surveys: (1) no hydrothermal activity could be found on the Futuna Spreading Centre (FSC) which sets the western limit of hydrothermal activity; (2) four distinct hydrothermal active areas were identified: Kulo Lasi Caldera, Amanaki Volcano, Fatu Kapa and Tasi Tulo areas; (3) extensive and diverse hydrothermal manifestations were observed and especially a 2D distribution of the sources. At Kulo Lasi, our data and especially tracer ratios (CH4/3He 50×106 and CH4/TDM 4.5) reveal a transient CH4 input, with elevated levels of CH4 measured in 2010, that had vanished in 2011, most likely caused by an eruptive magmatic event. By contrast at Amanaki, vertical tracer profiles and tracer ratios point to typical seawater/basalt interactions. Fatu Kapa is characterised by a substantial spatial variability of the hydrothermal water column anomalies, most likely due to widespread focused and diffuse hydrothermal discharge in the area. In the Tasi Tulo zone, the hydrothermal signal is characterised by a total lack of turbidity, although other tracer anomalies are in the same range as in nearby Fatu Kapa. The background data set revealed the presence of a Mn and 3He chronic plume due to the extensive and cumulative venting over the entire area. To that respect, we believe that the joined domain composed of our active area and the nearby active area discovered in the East by Lupton et al. (2012) highly contribute to the

  11. High-resolution water column survey to identify active sublacustrine hydrothermal discharge zones within Lake Rotomahana, North Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Walker, Sharon L.; de Ronde, Cornel E. J.; Fornari, Daniel; Tivey, Maurice A.; Stucker, Valerie K.

    2016-03-01

    Autonomous underwater vehicles were used to conduct a high-resolution water column survey of Lake Rotomahana using temperature, pH, turbidity, and oxidation-reduction potential (ORP) to identify active hydrothermal discharge zones within the lake. Five areas with active sublacustrine venting were identified: (1) the area of the historic Pink Terraces; (2) adjacent to the western shoreline subaerial "Steaming Cliffs," boiling springs and geyser; (3) along the northern shoreline to the east of the Pink Terrace site; (4) the newly discovered Patiti hydrothermal system along the south margin of the 1886 Tarawera eruption rift zone; and (5) a location in the east basin (northeast of Patiti Island). The Pink Terrace hydrothermal system was active prior to the 1886 eruption of Mount Tarawera, but venting along the western shoreline, in the east basin, and the Patiti hydrothermal system appear to have been initiated in the aftermath of the eruption, similar to Waimangu Valley to the southwest. Different combinations of turbidity, pH anomalies (both positive and negative), and ORP responses suggest vent fluid compositions vary over short distances within the lake. The seasonal period of stratification limits vertical transport of heat to the surface layer and the hypolimnion temperature of Lake Rotomahana consequently increases with an average warming rate of ~ 0.010 °C/day due to both convective hydrothermal discharge and conductive geothermal heating. A sudden temperature increase occurred during our 2011 survey and was likely the response to an earthquake swarm just 11 days prior.

  12. Shallow water submarine hydrothermal activity - A case study in the assessment of ocean acidification and fertilization

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Yoshida, K.; Hagiwara, T.; Nagao, K.; Kusakabe, M.; Wang, B.; Chen, C. A.

    2012-12-01

    Most natural Shallow Water submarine Hydrothermal activates (SWH) along coastlines are related to hydrothermal eruptions involving heating of groundwater with the volcanic gas. These SWHs supply nutrients such as phosphorus and micro nutrients like iron to the euphotic zone, contributing to the overall natural fertility and primary productivity of coastal waters. However, SWHs also have a negative effect, dispersing toxic materials such as mercury and arsenic, and affecting the acidification of the surrounding waters. In this study, we evaluate the impact of "iron supply" and "ocean acidification" on the primary production in a coastal marine environment, at a SWH area discovered off Gueshandao Island, northeast Taiwan. In the past three years, expeditions were conducted and observations made around this SWH site. Divers, small boats and a research vessel (R/V OR1, Ocean University National Taiwan) were used to survey successively larger areas around the site. Some of the results obtained are as follows. Hydrothermal vents are located in a hilly terrain rich with hot spring water with gas erupting intermittently. There are two types of vents, roughly divided by color, yellow hot spring water with higher temperature >110 degC ejected from sulfur chimneys of various sizes, and colorless water with lower temperature ~80 degC ejected directly from the crevices of the andesitic bedrock. Natural sulfur solidifying in the mouth of a small chimney was captured by a video camera, and explosions were also observed at intervals of a few minutes. Sediment, sand and particles of sulfur were deposited on the sides to a radius of about 50 m condensing around the chimney. The bottom type changes from sand/particles to outcrop/rock away from the vents. Moreover, gas samples were collected from the vents; the ratios of gas concentrations (N2/Ar) and isotopic composition of noble gas (3He/4He) suggest that these volcanic gases are mantle-derived. Hydrothermal fluid with high p

  13. Bioactive proteins and energy value of okara as a byproduct in hydrothermal processing of soy milk.

    PubMed

    Stanojevic, Sladjana P; Barac, Miroljub B; Pesic, Mirjana B; Jankovic, Vanja S; Vucelic-Radovic, Biljana V

    2013-09-25

    The nutritional properties of raw okara obtained as a byproduct from six soybean varieties during hydrothermal cooking (HTC) of soy milk were assessed. The composition and residual activity (rTIA) of trypsin inhibitors (TIs), contents of lectin, proteins, fats, and carbohydrates, and energy values (EV) were correlated with the respective physicochemical properties of soybean and okara. Kunitz (KTI) and Bowman-Birk (BBI) TIs both comprised okara rTIA. TIs content was higher in okara (5.19-14.40%) than in soybean (3.10-12.17%), which additionally enriched okara by cysteine. Contents of KTI (r = 1.00;p < 0.05) and BBI (r = 0.89;p < 0.05) as well as BBI monomeric (r = 0.89;p < 0.05) and polymeric forms (r = 0.95;p < 0.05) in okara and in soybean were strongly correlated. Low urease index activity indicated that okara was heated adequately to inactivate antinutritional factors. The proximate composition of raw okara, advantageous rTIA, and a very low EV (2.74-3.78 kJ/g) qualify this byproduct for potential application in food preparation as a functional ingredient in dietary products.

  14. Activity and hydrothermal stability of CeO₂-ZrO₂-WO₃ for the selective catalytic reduction of NOx with NH₃.

    PubMed

    Song, Zhongxian; Ning, Ping; Zhang, Qiulin; Li, Hao; Zhang, Jinhui; Wang, Yancai; Liu, Xin; Huang, Zhenzhen

    2016-04-01

    A series of CeO2-ZrO2-WO3 (CZW) catalysts prepared by a hydrothermal synthesis method showed excellent catalytic activity for selective catalytic reduction (SCR) of NO with NH3 over a wide temperature of 150-550°C. The effect of hydrothermal treatment of CZW catalysts on SCR activity was investigated in the presence of 10% H2O. The fresh catalyst showed above 90% NOx conversion at 201-459°C, which is applicable to diesel exhaust NOx purification (200-440°C). The SCR activity results indicated that hydrothermal aging decreased the SCR activity of CZW at low temperatures (below 300°C), while the activity was notably enhanced at high temperature (above 450°C). The aged CZW catalyst (hydrothermal aging at 700°C for 8 hr) showed almost 80% NOx conversion at 229-550°C, while the V2O5-WO3/TiO2 catalyst presented above 80% NOx conversion at 308-370°C. The effect of structural changes, acidity, and redox properties of CZW on the SCR activity was investigated. The results indicated that the excellent hydrothermal stability of CZW was mainly due to the CeO2-ZrO2 solid solution, amorphous WO3 phase and optimal acidity. In addition, the formation of WO3 clusters increased in size as the hydrothermal aging temperature increased, resulting in the collapse of structure, which could further affect the acidity and redox properties.

  15. Early Solar System hydrothermal activity in chondritic asteroids on 1–10-year timescales

    PubMed Central

    Dyl, Kathryn A.; Bischoff, Addi; Ziegler, Karen; Young, Edward D.; Wimmer, Karl; Bland, Phil A.

    2012-01-01

    Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar System. As undifferentiated objects, they also display widespread evidence of water–rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar System, and the formation of prebiotic molecules. The timescales of water–rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water–rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions. The profiles were modeled at T = 800 °C and P(H2O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa-1Al-1 exchange in a fumarole. The geochemical data are consistent with hydrothermal activity on the parent body lasting only 1–10 y. This result has wide-ranging implications for the geological history of chondritic asteroids. PMID:23093668

  16. Early Solar System hydrothermal activity in chondritic asteroids on 1-10-year timescales.

    PubMed

    Dyl, Kathryn A; Bischoff, Addi; Ziegler, Karen; Young, Edward D; Wimmer, Karl; Bland, Phil A

    2012-11-06

    Chondritic meteorites are considered the most primitive remnants of planetesimals from the early Solar System. As undifferentiated objects, they also display widespread evidence of water-rock interaction on the parent body. Understanding this history has implications for the formation of planetary bodies, the delivery of water to the inner Solar System, and the formation of prebiotic molecules. The timescales of water-rock reactions in these early objects, however, are largely unknown. Here, we report evidence for short-lived water-rock reactions in the highly metamorphosed ordinary chondrite breccia Villalbeto de la Peña (L6). An exotic clast (d = 2cm) has coexisting variations in feldspar composition and oxygen isotope ratios that can only result from hydrothermal conditions. The profiles were modeled at T = 800 °C and P(H(2)O) = 1 bar using modified grain-boundary diffusion parameters for oxygen self-diffusion and reaction rates of NaSiCa(-1)Al(-1) exchange in a fumarole. The geochemical data are consistent with hydrothermal activity on the parent body lasting only 1-10 y. This result has wide-ranging implications for the geological history of chondritic asteroids.

  17. Debris flow evolution and the activation of an explosive hydrothermal system; Te Maari, Tongariro, New Zealand

    NASA Astrophysics Data System (ADS)

    Procter, J. N.; Cronin, S. J.; Zernack, A. V.; Lube, G.; Stewart, R. B.; Nemeth, K.; Keys, H.

    2014-10-01

    Analysis of the pre- and post-eruption topography, together with observations of the avalanche deposition sequence, yields a triggering mechanism for the 6 August 2012 eruption of Upper Te Maari. The avalanche was composed of a wedge of c. 683 000-774 000 m3 of coarse breccia, spatter and clay-rich tuffs and diamictons which slid from the western flanks of the Upper Te Maari Crater, the failure plane is considered to be a hydrothermally altered clay layer. This landslide led to a pressure drop of up to 0.5 MPa, enough to generate an explosive eruption from the hydrothermal system below, which had been activated over the months earlier by additional heat and gas from a shallow intrusion. The landslide transformed after c. 700 m into a clay-rich cohesive debris flow, eroding soils from steep, narrow stretches of channel, before depositing on intermediate broad flatter reaches. After each erosive reach, the debris flow contained greater clay and mud contents and became more mobile. At c. 2 km flow distance, however, the unsaturated flow stopped, due to a lack of excess pore pressure. This volume controlled flow deposited thick, steep sided lobes behind an outer levee, accreting inward and upward to form a series of curved surface ridges.

  18. Fabrication of carbon/SiO2 composites from the hydrothermal carbonization process of polysaccharide and their adsorption performance.

    PubMed

    Li, Yinhui; Li, Kunyu; Su, Min; Ren, Yanmei; Li, Ying; Chen, Jianxin; Li, Liang

    2016-11-20

    In this work, carbon/SiO2 composites, using amylose and tetraethyl orthosilicate (TEOS) as raw materials, were successfully prepared by a facial hydrothermal carbonization process. The carbon/SiO2 composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption and Thermogravimetric (TG) analysis. The composites, which were made up of amorphous SiO2 and amorphous carbon, were found to have hierarchical porous structures. The mass ratios of amylose and SiO2 and the hydrothermal carbonization time had significant effects on the morphology of the composites, which had three shapes including monodispersed spheres, porous pieces and the nano-fibers combined with nano-spheres structures. The adsorption performance of the composites was studied using Pb(2+) as simulated contaminants from water. When the mass ratio of amylose and SiO2 was 9/1, the hydrothermal time was 30h and the hydrothermal temperature was 180°C, the adsorption capacity of the composites achieved to 52mg/g. Experimental data show that adsorption kinetics of the carbon/SiO2 composites can be fitted well by the Elovich model, while the isothermal data can be perfectly described by the Langmuir adsorption model and Freundlich adsorption model. The maximum adsorption capacity of the carbon/SiO2 composites is 56.18mgg(-1).

  19. New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece.

    PubMed

    Kilias, Stephanos P; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

    2013-01-01

    We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe(3+)-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe(2+)-oxidation, dependent on microbially produced nitrate.

  20. New insights into hydrothermal vent processes in the unique shallow-submarine arc-volcano, Kolumbo (Santorini), Greece

    PubMed Central

    Kilias, Stephanos P.; Nomikou, Paraskevi; Papanikolaou, Dimitrios; Polymenakou, Paraskevi N.; Godelitsas, Athanasios; Argyraki, Ariadne; Carey, Steven; Gamaletsos, Platon; Mertzimekis, Theo J.; Stathopoulou, Eleni; Goettlicher, Joerg; Steininger, Ralph; Betzelou, Konstantina; Livanos, Isidoros; Christakis, Christos; Bell, Katherine Croff; Scoullos, Michael

    2013-01-01

    We report on integrated geomorphological, mineralogical, geochemical and biological investigations of the hydrothermal vent field located on the floor of the density-stratified acidic (pH ~ 5) crater of the Kolumbo shallow-submarine arc-volcano, near Santorini. Kolumbo features rare geodynamic setting at convergent boundaries, where arc-volcanism and seafloor hydrothermal activity are occurring in thinned continental crust. Special focus is given to unique enrichments of polymetallic spires in Sb and Tl (±Hg, As, Au, Ag, Zn) indicating a new hybrid seafloor analogue of epithermal-to-volcanic-hosted-massive-sulphide deposits. Iron microbial-mat analyses reveal dominating ferrihydrite-type phases, and high-proportion of microbial sequences akin to "Nitrosopumilus maritimus", a mesophilic Thaumarchaeota strain capable of chemoautotrophic growth on hydrothermal ammonia and CO2. Our findings highlight that acidic shallow-submarine hydrothermal vents nourish marine ecosystems in which nitrifying Archaea are important and suggest ferrihydrite-type Fe3+-(hydrated)-oxyhydroxides in associated low-temperature iron mats are formed by anaerobic Fe2+-oxidation, dependent on microbially produced nitrate. PMID:23939372

  1. Synthesis of polyethylenimine (PEI) functionalized silver nanoparticles by a hydrothermal method and their antibacterial activity study.

    PubMed

    Liu, Zhiguo; Wang, Yuanlin; Zu, Yuangang; Fu, Yujie; Li, Na; Guo, Na; Liu, Ruisi; Zhang, Yiming

    2014-09-01

    In this study, we report a facile, one-step hydrothermal method to synthesize PEI-functionalized Ag nanoparticles in which no extra reducing agent is needed and PEI serves as a reducing agent and a stabilizing agent. The obtained Ag colloids have been characterized by TEM, UV absorption spectra and laser particle size analyzer. We found that the size of Ag nanoparticles can be tuned through the alteration of the temperature and growth mode. Under an acidic condition, PEI-functionalized Ag nanoparticles are positively charged. More importantly, the Ag colloids exhibited stronger antibacterial activity in the bactericidal test. Its bactericidal efficiency exceeds the commonly used antibacterial agents such as Erythromycin, chloramphenicol and penicillin as well as AgNO3 solution. These results prove that our synthesis method is very efficient to produce a stable PEI-functionalized Ag colloid with excellent antibacterial activity.

  2. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity.

    PubMed

    Alanis, Paul K B; Yamaya, Yusuke; Takeuchi, Akihiro; Sasai, Yoichi; Okada, Yoshihiro; Nagao, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km×3 km×3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano's activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions.

  3. A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity

    PubMed Central

    ALANIS, Paul K. B.; YAMAYA, Yusuke; TAKEUCHI, Akihiro; SASAI, Yoichi; OKADA, Yoshihiro; NAGAO, Toshiyasu

    2013-01-01

    Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km × 3 km × 3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano’s activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions. PMID:24126286

  4. Dynamics of the Yellowstone hydrothermal system

    USGS Publications Warehouse

    Hurwitz, Shaul; Lowenstern, Jacob B.

    2014-01-01

    The Yellowstone Plateau Volcanic Field is characterized by extensive seismicity, episodes of uplift and subsidence, and a hydrothermal system that comprises more than 10,000 thermal features, including geysers, fumaroles, mud pots, thermal springs, and hydrothermal explosion craters. The diverse chemical and isotopic compositions of waters and gases derive from mantle, crustal, and meteoric sources and extensive water-gas-rock interaction at variable pressures and temperatures. The thermal features are host to all domains of life that utilize diverse inorganic sources of energy for metabolism. The unique and exceptional features of the hydrothermal system have attracted numerous researchers to Yellowstone beginning with the Washburn and Hayden expeditions in the 1870s. Since a seminal review published a quarter of a century ago, research in many fields has greatly advanced our understanding of the many coupled processes operating in and on the hydrothermal system. Specific advances include more refined geophysical images of the magmatic system, better constraints on the time scale of magmatic processes, characterization of fluid sources and water-rock interactions, quantitative estimates of heat and magmatic volatile fluxes, discovering and quantifying the role of thermophile microorganisms in the geochemical cycle, defining the chronology of hydrothermal explosions and their relation to glacial cycles, defining possible links between hydrothermal activity, deformation, and seismicity; quantifying geyser dynamics; and the discovery of extensive hydrothermal activity in Yellowstone Lake. Discussion of these many advances forms the basis of this review.

  5. Life cycle assessment of microalgae to biofuel: Thermochemical processing through hydrothermal liquefaction or pyrolysis

    NASA Astrophysics Data System (ADS)

    Bennion, Edward P.

    Microalgae are currently being investigated as a renewable transportation fuel feedstock based on various advantages that include high annual yields, utilization of poor quality land, does not compete with food, and can be integrated with various waste streams. This study focuses on directly assessing the impact of two different thermochemical conversion technologies on the microalgae-to-biofuel process through life cycle assessment. A system boundary of a "well to pump" (WTP) is defined and includes sub-process models of the growth, dewatering, thermochemical bio-oil recovery, bio-oil stabilization, conversion to renewable diesel, and transport to the pump. Models were validated with experimental and literature data and are representative of an industrial-scale microalgae-to-biofuel process. Two different thermochemical bio-oil conversion systems are modeled and compared on a systems level, hydrothermal liquefaction (HTL) and pyrolysis. The environmental impact of the two pathways were quantified on the metrics of net energy ratio (NER), defined here as energy consumed over energy produced, and greenhouse gas (GHG) emissions. Results for WTP biofuel production through the HTL pathway were determined to be 1.23 for the NER and GHG emissions of -11.4 g CO2 eq (MJ renewable diesel)-1. WTP biofuel production through the pyrolysis pathway results in a NER of 2.27 and GHG emissions of 210 g CO2 eq (MJ renewable diesel)-1. The large environmental impact associated with the pyrolysis pathway is attributed to feedstock drying requirements and combustion of co-products to improve system energetics. Discussion focuses on a detailed breakdown of the overall process energetics and GHGs, impact of modeling at laboratory-scale compared to industrial-scale, environmental impact sensitivity to engineering systems input parameters for future focused research and development, and a comparison of results to literature.

  6. Characterization of yellow rice and development of instant flours by hydrothermal process.

    PubMed

    Martínez-Bustos, F; Delgado, L L; Victorio, M G; Morales, S E

    1997-03-01

    Commercial brown and yellow milled rice submitted to inappropriate storage conditions were characterized and utilized to develop instant flours that were used in the preparation of atoles. The grains were classified as long-thin; the average size was 2.13 x 6.79 mm. The milling yields obtained in laboratory with paddy rice were 70% brown rice and 60% milled rice. Brown rice and yellow milled rice had similar amylose contents, 22.5 and 25.6% respectively. Gel consistency was soft with low gelatinization temperature (63-68 degrees C) for both samples. Field fungi, such as Helminthosporium oryzae, and storage fungi, such as Aspergillus spp, were present in paddy, yellow milled and commercial rice. The fungus Helminthosporium oryzae, Aspergillus spp, and Penicillum spp were not present in instant flours. Instant flours were prepared by soaking the grain in water, and then steaming, drying and milling it. The highest values for water absorption index were obtained from yellow milled instant rice flour. The color of yellow milled instant rice flour varied from white ("L") to pale yellow (lesser values of "b"). The lower viscosity of the instant flours indicates the breakdown of polymers and reveals that unintact starch granules were not present in instant flours. Protein and ash contents of brown and milled rice were unaffected by hydrothermal process, and the lipid content showed only little changes. Sensory analyses carried out on the atoles prepared with instant flours considered them acceptable, specially for products made from milled yellow rice.

  7. Hydrothermally Processed Photosensitive Field-Effect Transistor Based on ZnO Nanorod Networks

    NASA Astrophysics Data System (ADS)

    Kumar, Ashish; Bhargava, Kshitij; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

    2016-11-01

    Formation of a stable, reproducible zinc oxide (ZnO) nanorod-network-based photosensitive field-effect transistor using a hydrothermal process at low temperature has been demonstrated. K2Cr2O7 additive was used to improve adhesion and facilitate growth of the ZnO nanorod network over the SiO2/Si substrate. Transistor characteristics obtained in the dark resemble those of the n-channel-mode field-effect transistor (FET). The devices showed I on/ I off ratio above 8 × 102 under dark condition, field-effect mobility of 4.49 cm2 V-1 s-1, and threshold voltage of -12 V. Further, under ultraviolet (UV) illumination, the FET exhibited sensitivity of 2.7 × 102 in off-state (-10 V) versus 1.4 in on-state (+9.7 V) of operation. FETs based on such nanorod networks showed good photoresponse, which is attributed to the large surface area of the nanorod network. The growth temperature for ZnO nanorod networks was kept at 110°C, enabling a low-temperature, cost-effective, simple approach for high-performance ZnO-based FETs for large-scale production. The role of network interfaces in the FET performance is also discussed.

  8. Hydrothermal Processes and Mobile Element Transport in Martian Impact Craters - Evidence from Terrestrial Analogue Craters

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Dressler, B. L.

    2005-01-01

    Hydrothermal alteration and chemical transport involving impact craters probably occurred on Mars throughout its history. Our studies of alteration products and mobile element transport in ejecta blanket and drill core samples from impact craters show that these processes may have contributed to the surface composition of Mars. Recent work on the Chicxulub Yaxcopoil-1 drill core has provided important information on the relative mobility of many elements that may be relevant to Mars. The Chicxulub impact structure in the Yucatan Peninsula of Mexico and offshore in the Gulf of Mexico is one of the largest impact craters identified on the Earth, has a diameter of 180-200 km, and is associated with the mass extinctions at the K/T boundary. The Yax-1 hole was drilled in 2001 and 2002 on the Yaxcopoil hacienda near Merida on the Yucatan Peninsula. Yax-1 is located just outside of the transient cavity, which explains some of the unusual characteristics of the core stratigraphy. No typical impact melt sheet was encountered in the hole and most of the Yax-1 impactites are breccias. In particular, the impact melt and breccias are only 100 m thick which is surprising taking into account the considerably thicker breccia accumulations towards the center of the structure and farther outside the transient crater encountered by other drill holes.

  9. Controllable synthesis of ultrathin vanadium oxide nanobelts via an EDTA-mediated hydrothermal process

    NASA Astrophysics Data System (ADS)

    Yu-Xiang, Qin; Cheng, Liu; Wei-Wei, Xie; Meng-Yang, Cui

    2016-02-01

    Ultrathin VO2 nanobelts with rough alignment features are prepared on the induction layer-coated substrates by an ethylenediaminetetraacetic acid (EDTA)-mediated hydrothermal process. EDTA acts as a chelating reagent and capping agent to facilitate the one-dimensional (1D) preferential growth of ultrathin VO2 nanobelts with high crystallinities and good uniformities. The annealed induction layer and concentration of EDTA are found to play crucial roles in the formation of aligned and ultrathin nanobelts. Variation in EDTA concentration can change the VO2 morphology of ultrathin nanobelts into that of thick nanoplates. Mild annealing of ultrathin VO2 nanobelts at 350 °C in air results in the formation of V2O5 nanobelts with a nearly unchanged ultrathin structure. The nucleation and growth mechanism involved in the formations of nanobelts and nanoplates are proposed. The ethanol gas sensing properties of the V2O5 nanobelt networks-based sensor are investigated in a temperature range from 100 °C to 300 °C over ethanol concentrations ranging from 3 ppm to 500 ppm. The results indicate that the V2O5 nanobelt network sensor exhibits high sensitivity, good reversibility, and fast response-recovery characteristics with an optimal working temperature of 250 °C. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274074, 61271070, and 61574100).

  10. Coupled sulfur isotopic and chemical mass transfer modeling: Approach and application to dynamic hydrothermal processes

    SciTech Connect

    Janecky, D.R.

    1988-09-21

    A computational modeling code (EQPSreverse arrowS) has been developed to examine sulfur isotopic distribution pathways coupled with calculations of chemical mass transfer pathways. A post processor approach to EQ6 calculations was chosen so that a variety of isotopic pathways could be examined for each reaction pathway. Two types of major bounding conditions were implemented: (1) equilibrium isotopic exchange between sulfate and sulfide species or exchange only accompanying chemical reduction and oxidation events, and (2) existence or lack of isotopic exchange between solution species and precipitated minerals, parallel to the open and closed chemical system formulations of chemical mass transfer modeling codes. All of the chemical data necessary to explicitly calculate isotopic distribution pathways is generated by most mass transfer modeling codes and can be input to the EQPS code. Routines are built in to directly handle EQ6 tabular files. Chemical reaction models of seafloor hydrothermal vent processes and accompanying sulfur isotopic distribution pathways illustrate the capabilities of coupling EQPSreverse arrowS with EQ6 calculations, including the extent of differences that can exist due to the isotopic bounding condition assumptions described above. 11 refs., 2 figs.

  11. Luminescence properties of ZnS:Cu, Eu semiconductor nanocrystals synthesized by a hydrothermal process

    NASA Astrophysics Data System (ADS)

    Xin, Mei; Hu, Li-Zhong

    2013-08-01

    ZnS:Cu, Eu nanocrystals with an average diameter of ~ 80 nm are synthesized using a hydrothermal approach at 200 °C. The photoluminescence (PL) properties of the ZnS:Cu, Eu nanocrystals before and after annealing, as well as the doping form of Eu, are studied. The as-synthesized samples are characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, and the excitation and emission spectra (PL). The results show that both Cu and Eu are indeed incorporated into the ZnS matrix. Compared with the PL spectrum of the Cu mono-doped sample, the PL emission intensity of the Cu and Eu-codoped sample increases and a peak appears at 516 nm, indicating that Eu3+ ions, which act as an impurity compensator and activator, are incorporated into the ZnS matrix, forming a donor level. Compared with the unannealed sample, the annealed one has an increased PL emission intensity and the peak position has a blue shift of 56 nm from 516 nm to 460 nm, which means that Eu3+ ions reduce to Eu2+ ions, thereby leading to the appearance of Eu2+ characteristic emission and generating effective host-to-Eu2+ energy transfer. The results indicate the potential applications of ZnS:Cu, Eu nanoparticles in optoelectronic devices.

  12. Hydrothermal treatment and enzymatic hydrolysis of Tamarix ramosissima: evaluation of the process as a conversion method in a biorefinery concept.

    PubMed

    Xiao, Ling-Ping; Shi, Zheng-Jun; Xu, Feng; Sun, Run-Cang

    2013-05-01

    The present work investigated the effects of hydrothermal treatment (HTT) of Tamarix ramosissima by determination of sugar and inhibitor formation in the liquid fraction, and chemical and morphological changes of the pretreated solid material coupled with an evaluation of enzymatic hydrolysis. HTT was carried out in a batch reactor system at a maximal temperature (TMAX 180-240 °C) and evaluated for severities logRo ranging from 2.40 to 4.17. The liquid fractions were analyzed by HPLC, GPC, and GC-MS. The morphology and composition of the solid residues were characterized using an array of techniques, such as SEM, XRD, BET surface area, and CP/MAS (13)C NMR. Using a variety of tools, we have developed a better understanding of how HTT process affects biomass structure and cellulose properties that impact on its digestibility. These results provided new insights into the factors limiting enzymatic digestibility and mechanism of biomass deconstruction during hydrothermal process.

  13. Evaluation of the US DOE's conceptual model of hydrothermal activity at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Dublyansky, Y. V.

    2012-11-01

    A unique conceptual model envisaging conductive heating of rocks in the thick unsaturated zone of Yucca Mountain, Nevada by a silicic pluton emplaced several kilometers away is accepted by the US Department of Energy (DOE) as an explanation of the elevated depositional temperatures measured in fluid inclusions in secondary fluorite and calcite. Acceptance of this model allowed the DOE not to consider hydrothermal activity in the performance assessment of the proposed high-level nuclear waste disposal facility. Evaluation shows that validation of the model by computational modeling and by observations at a natural analog site was unsuccessful. Due to the lack of validation, the reliance on this model must be discontinued and the scientific defensibility of decisions which rely on this model must be re-evaluated.

  14. Enhanced East Pacific Rise hydrothermal activity during the last two glacial terminations.

    PubMed

    Lund, D C; Asimow, P D; Farley, K A; Rooney, T O; Seeley, E; Jackson, E W; Durham, Z M

    2016-01-29

    Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Melt production is apparently modulated by glacial-interglacial changes in sea level, raising the possibility that magmatic flux acts as a negative feedback on ice-sheet size. The timing of melt variability is poorly constrained, however, precluding a clear link between ridge magmatism and Pleistocene climate transitions. Here we present well-dated sedimentary records from the East Pacific Rise that show evidence of enhanced hydrothermal activity during the last two glacial terminations. We suggest that glacial maxima and lowering of sea level caused anomalous melting in the upper mantle and that the subsequent magmatic anomalies promoted deglaciation through the release of mantle heat and carbon at mid-ocean ridges.

  15. ESR dating of barite in sulphide deposits formed by the sea-floor hydrothermal activities.

    PubMed

    Toyoda, Shin; Fujiwara, Taisei; Uchida, Ai; Ishibashi, Jun-ichiro; Nakai, Shun'ichi; Takamasa, Asako

    2014-06-01

    Barite is a mineral newly found to be practically useful for electron spin resonance (ESR) dating of sulphide deposits formed by the sea-floor hydrothermal activities. The recent studies for the properties of the ESR dating signal in barite are summarised in the present paper as well as the formulas for corrections for accurate dose-rate estimation are developed including the dose-rate conversion factors, shape correction for gamma-ray dose and decay of (226)Ra. Although development of the techniques for ESR dating of barite has been completed, further comparative studies with other dating techniques such as U-Th and (226)Ra-(210)Pb dating are necessary for the technique to be widely used.

  16. Enhanced East Pacific Rise hydrothermal activity during the last two glacial terminations

    NASA Astrophysics Data System (ADS)

    Lund, D. C.; Asimow, P. D.; Farley, K. A.; Rooney, T. O.; Seeley, E.; Jackson, E. W.; Durham, Z. M.

    2016-01-01

    Mid-ocean ridge magmatism is driven by seafloor spreading and decompression melting of the upper mantle. Melt production is apparently modulated by glacial-interglacial changes in sea level, raising the possibility that magmatic flux acts as a negative feedback on ice-sheet size. The timing of melt variability is poorly constrained, however, precluding a clear link between ridge magmatism and Pleistocene climate transitions. Here we present well-dated sedimentary records from the East Pacific Rise that show evidence of enhanced hydrothermal activity during the last two glacial terminations. We suggest that glacial maxima and lowering of sea level caused anomalous melting in the upper mantle and that the subsequent magmatic anomalies promoted deglaciation through the release of mantle heat and carbon at mid-ocean ridges.

  17. Tracking Stress and Hydrothermal Activity Along Oceanic Spreading Centers Using Tomographic Images of Seismic Anisotropy

    NASA Astrophysics Data System (ADS)

    Dunn, R. A.; Conder, J. A.; Canales, J. P.

    2014-12-01

    Marine controlled-source seismic tomography experiments now utilize 50+ ocean-bottom seismographs and source grids consisting of many tens of seismic lines with <500 m shot spacing. These dense experiments focus on the upper 10 km of the lithosphere over areas approaching 9000 sq-km. Because of the dense sampling and large azimuthal coverage of ray paths (200,000+ travel time measurements possible), it is now feasible to solve for 3-D images of P-wave azimuthal anisotropy with resolving lengths approaching 1km. Recent examples include the L-SCAN and MARINER experiments, performed at the Eastern Lau Spreading Center and Mid-Atlantic Ridge (36N), respectively. In each case, background anisotropy of ~4% is found in the upper 3-4 km of lithosphere and is consistent with pervasive stress-aligned cracks and microcracks. The fast axes are generally oriented parallel to the trend of the spreading center, as expected for cracks that form in association with seafloor spreading. Three-dimensional images of anisotropy magnitude and orientation reveal variations interpreted as arising from changes in the ambient stress field. Near the ends of ridge segments, where the ridge axis jumps from one spreading center to the next, anisotropy is high with orientations that are out of alignment relative to the background trend. This agrees with numerical models and seafloor morphology that suggest tensile stress concentration and brittle crack formation in these areas. Anisotropy also increases in areas along the ridges where the underlying magma supply and hydrothermal output are greater. This is opposite the trend expected if simple tectonic stress models govern anisotropy. Increased hydrothermal activity, due to increased magma supply, can explain higher anisotropy via increased pore pressure and hydrofracturing. These studies provide the first evidence that images of seismic anisotropy can be used to map variations in hydrologic activity along the crests of oceanic spreading centers.

  18. Diffuse flow hydrothermal manganese mineralization along the active Mariana and southern Izu-Bonin arc system, western Pacific

    USGS Publications Warehouse

    Hein, J.R.; Schulz, M.S.; Dunham, R.E.; Stern, R.J.; Bloomer, S.H.

    2008-01-01

    Abundant ferromanganese oxides were collected along 1200 km of the active Izu-Bonin-Mariana arc system. Chemical compositions and mineralogy show that samples were collected from two deposit types: Fe-Mn crusts of mixed hydrogenetic/hydrothermal origin and hydrothermal Mn oxide deposits; this paper addresses only the second type. Mn oxides cement volcaniclastic and biogenic sandstone and breccia layers (Mn sandstone) and form discrete dense stratabound layers along bedding planes and within beds (stratabound Mn). The Mn oxide was deposited within coarse-grained sediments from diffuse flow systems where precipitation occurred below the seafloor. Deposits were exposed at the seabed by faulting, mass wasting, and erosion. Scanning electron microscopy and microprobe analyses indicate the presence of both amorphous and crystalline 10 ?? and 7 ?? manganate minerals, the fundamental chemical difference being high water contents in the amorphous Mn oxides. Alternation of amorphous and crystalline laminae occurs in many samples, which likely resulted from initial rapid precipitation of amorphous Mn oxides from waxing pulses of hydrothermal fluids followed by precipitation of slow forming crystallites during waning stages. The chemical composition is characteristic of a hydrothermal origin including strong fractionation between Fe (mean 0.9 wt %) and Mn (mean 48 wt %) for the stratabound Mn, generally low trace metal contents, and very low rare earth element and platinum group element contents. However, Mo, Cd, Zn, Cu, Ni, and Co occur in high concentrations in some samples and may be good indicator elements for proximity to the heat source or to massive sulfide deposits. For the Mn sandstones, Fe (mean-8.4%) and Mn (12.4%) are not significantly fractionated because of high Fe contents in the volcaniclastic material. However, the proportion of hydrothermal Fe (nondetrital Fe) to total Fe is remarkably constant (49-58%) for all the sample groups, regardless of the degree of

  19. Enhanced electrorheological performance and antisedimentation property of mesoporous anatase TiO2 shell prepared by hydrothermal process

    NASA Astrophysics Data System (ADS)

    Wang, Jiahui; Chen, Guowei; Yin, Jianbo; Luo, Chunrong; Zhao, Xiaopeng

    2017-03-01

    Mesoporous anatase TiO2 hollow microspheres (MTHMs) with a high surface area (231.1 m2 g‑1) were synthesized by sol-gel template-assisted approach and hydrothermal process. The materials possessed a uniform diameter of about 620 nm and a mesoporous shell with thickness of about 180 nm. The microspheres were used as dispersing materials for electrorheological (ER) fluids, which exhibited better ER performance and antisedimentation property than common anatase TiO2 hollow microspheres and ordinary anatase TiO2 particles. The yield stress of the MTHM-based ER fluid (30.0 vol%) was approximately 7.8 kPa under an electric field of 3 kV mm‑1, and the sedimentation ratio was maintained above 78% after 250 h. The good ER activity of the MTHM-based ER fluid was mainly attributed to the high surface effect provided by mesoporous and hollow structure of the MTHMs, leading to a high interfacial polarization under the action of an external electric field. The mesoporous and hollow structure also improved the antisedimentation property of the suspensions by lowering the density of microspheres.

  20. METEORIC-HYDROTHERMAL SYSTEMS.

    USGS Publications Warehouse

    Criss, Robert E.; Taylor, Hugh P.

    1986-01-01

    This paper summarizes the salient characteristics of meteoric-hydrothermal systems, emphasing the isotopic systematics. Discussions of permeable-medium fluid dynamics and the geology and geochemistry of modern geothermal systems are also provided, because they are essential to any understanding of hydrothermal circulation. The main focus of the paper is on regions of ancient meteoric-hydrothermal activity, which give us information about the presently inaccessible, deep-level parts of modern geothermal systems. It is shown oxygen and hydrogen isotopes provide a powerful method to discover and map fossil hydrothermal systems and to investigate diverse associated aspects of rock alteration and ore deposition.

  1. Recovery of alumina and alkali in Bayer red mud by the formation of andradite-grossular hydrogarnet in hydrothermal process.

    PubMed

    Zhang, Ran; Zheng, Shili; Ma, Shuhua; Zhang, Yi

    2011-05-30

    Bayer red mud (RM) is an alumina refinery waste product rich in aluminum oxides and alkalis which are present primarily in the form of sodium hydro-aluminosilicate desilication product (DSP). A hydrothermal process was employed to recover alumina and alkali from "Fe-rich" and "Fe-lean" RM, the two representative species of RM produced in China. The hydrothermal process objective phase is andradite-grossular hydrogarnet characterized by the isomorphic substitution of Al and Fe. Batch experiments were used to evaluate the main factors influencing the recovery process, namely reaction temperature, caustic ratio (molar ratio of Na(2)O to Al(2)O(3) in sodium solution), sodium concentration and residence time. The results revealed that the Na(2)O content of 0.5 wt% and A/S of 0.3 (mass ratio of Al(2)O(3) to SiO(2)) in leached residue could be achieved with Fe-rich RM under optimal conditions. However, the hydrothermal treatment of Fe-lean RM proved less successful unless the reaction system was enriched with iron. Subsequent experiments examined the effects of the ferric compound's content and type on the substitution ratio.

  2. The effect of stirring in the hydrothermal process to convert the mixed municipal solid waste into uniform solid fuel

    NASA Astrophysics Data System (ADS)

    Prawisudha, P.; Mu'min, G. F.; Yoshikawa, K.; Pasek, A. D.

    2016-06-01

    An innovative waste treatment technology has been developed in Indonesia to treat the mixed municipal solid waste into a solid fuel by employing the hydrothermal process. A mixture of organic and plastic waste was treated in a 2.5 L reactor using saturated steam in the temperature range of 120 to 180 °C. Two modes of operation were employed to achieve two different goals, i.e. without stirring (NS mode) and with stirring (WS mode). It was observed that both modes resulted in increasing density of product up to twofold of the raw MSW. In NS mode, the processed mixed MSW was converted into two different products; however, in WS mode the bulky plastic was converted into small granules, producing a uniform product. The results suggest that by hydrothermal treatment, the organic fibers in the organic parts are trapped into the plastic, and the stirring breaks the bulky plastics, producing uniform granules suitable as solid fuel. Therefore, the stirring during the hydrothermal process can be a solution to treat the MSW as it is, without any separation, to produce a clean and renewable energy source.

  3. Transportability Class of Americium in K Basin Sludge under Ambient and Hydrothermal Processing Conditions

    SciTech Connect

    Delegard, Calvin H.; Schmitt, Bruce E.; Schmidt, Andrew J.

    2006-08-01

    data is derived spent nuclear fuel corroded within the K Basins at 10-15?C. The STP process will place water-laden sludges from the K Basin in process vessels at {approx}150-180 C. Therefore, published studies with other irradiated (uranium oxide) fuel were examined. From these studies, the affinity of plutonium and americium for uranium in irradiated UO2 also was demonstrated at hydrothermal conditions (150 C anoxic liquid water) approaching those proposed for the STP process and even for hydrothermal conditions outside of the STP operating envelope (e.g., 150 C oxic and 100 C oxic and anoxic liquid water). In summary, by demonstrating that the chemical and physical behavior of 241Am in the sludge matrix is similar to that of the predominant species (uranium and for the plutonium from which it originates), a technical basis is provided for using the slow uptake transportability factor for 241Am that is currently used for plutonium and uranium oxides. The change from moderate to slow uptake for 241Am could reduce the overall analyzed dose consequences for the STP by more than 30%.

  4. Metaproteomic Analysis of a Chemosynthetic Hydrothermal Vent Community Reveals Insights into Key-Metabolic Processes

    NASA Astrophysics Data System (ADS)

    Steen, I.; Stokke, R.; Lanzen, A.; Pedersen, R.; Øvreås, L.; Urich, T.

    2010-12-01

    In 2005 researchers at the Centre for Geobiology, University of Bergen, Norway, discovered two active vent fields at the southwestern Mohns Ridge in the Norwegian-Greenland Sea. The fields harbours both low-temperature iron deposits and high-temperature white smoker vents. Distinct microbial mats were abundantly present and located in close vicinity to the hydrothermal vent sites. Characteristics of the mat environment were steep physical and chemical gradients with temperatures ranging from 10°C in the top layer to 90°C at 10 cm bsf and high concentrations of hydrogen sulfide and methane. The work presented here focus on the In situ community activities, and is part of an integrated strategy combining metagenomics, metatranscriptomics and metaproteomics to in-depth characterise these newly discovered hydrothermal vent communities. Extracted proteins were separated via SDS-PAGE. Peptides extracted after In-gel tryptic digest was injected into an Ultimate 3000 nanoLC system connected to a linear quadropole ion trap-orbitrap (LTQ-Orbitrap XL) mass spectrometer equipped with a nanoelectrospray ion source. A custom database of open reading frames (ORFs) from the combined metatranscriptome and metagenome datasets was implemented and searched against using Mascot 2.2; the IRMa tool box [1] was used in peptide validation. Validated ORFs were subjected to a Blastp search against Refseq with an E-value cut-off of 0.001. A total of 1097 proteins with ≥ 2 peptides were identified of which 921 gave a hit against Refseq, containing 519 unique proteins. Key enzymes of the sulfur oxidation pathway (sox) were found, which were taxonomically affiliated to Epsilonproteobacteria. In addition, this group actively expressed hydrogenases and membrane proteins involved in aerobic and anaerobic respiratory chains. Enzymes of dissimilatory sulfate-reduction (APS-reductase, AprAB and DsrA2) were found with closest hit to members of the Deltaproteobacteria. These findings indicate an

  5. Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A.

    USGS Publications Warehouse

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

    2010-01-01

    Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

  6. Diversity of Active Seafloor Hydrothermal Mineralization in the Manus Back-Arc Basin, Papua New Guinea

    NASA Astrophysics Data System (ADS)

    Gena, K.; Chiba, H.

    2004-12-01

    sulfidation mineralization is considered to be a product of magmatic degassing and is a typical example of an acid-sulphate type of hydrothermal activity developing on the seafloor.

  7. Enhanced sludge processing of HLW: Hydrothermal oxidation of chromium, technetium, and complexants by nitrate. 1997 mid-year progress report

    SciTech Connect

    Buelow, S.

    1997-06-01

    'Treatment of High Level Waste (HLW) is the second most costly problem identified by OEM. In order to minimize costs of disposal, the volume of HLW requiring vitrification and long term storage must be reduced. Methods for efficient separation of chromium from waste sludges, such as the Hanford Tank Wastes (HTW), are key to achieving this goal since the allowed level of chromium in high level glass controls waste loading. At concentrations above 0.5 to 1.0 wt.% chromium prevents proper vitrification of the waste. Chromium in sludges most likely exists as extremely insoluble oxides and minerals, with chromium in the plus III oxidation state [1]. In order to solubilize and separate it from other sludge components, Cr(III) must be oxidized to the more soluble Cr(VI) state. Efficient separation of chromium from HLW could produce an estimated savings of $3.4B[2]. Additionally, the efficient separation of technetium [3], TRU, and other metals may require the reformulation of solids to free trapped species as well as the destruction of organic complexants. New chemical processes are needed to separate chromium and other metals from tank wastes. Ideally they should not utilize additional reagents which would increase waste volume or require subsequent removal. The goal of this project is to apply hydrothermal processing for enhanced chromium separation from HLW sludges. Initially, the authors seek to develop a fundamental understanding of chromium speciation, oxidation/reduction and dissolution kinetics, reaction mechanisms, and transport properties under hydrothermal conditions in both simple and complex salt solutions. The authors also wish to evaluate the potential of hydrothermal processing for enhanced separations of technetium and TRU by examining technetium and TRU speciation at hydrothermal conditions optimal for chromium dissolution.'

  8. Age, Episodicity and Migration of Hydrothermal Activity within the Axial Valley, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Jamieson, J. W.; Hannington, M. D.; Kelley, D. S.; Clague, D. A.; Holden, J. F.; Tivey, M. K.; Delaney, J. R.

    2011-12-01

    Hydrothermal sulfide deposits record the history of high-temperature venting along the Endeavour Segment. Active venting is currently located within five discreet vent fields, with minor diffuse venting occurring between the fields. However, inactive and/or extinct sulfide structures are found throughout the entire axial valley of the ridge segment, suggesting that hydrothermal activity has been more vigorous in the past or focused venting has migrated with time. Here, we present age constraints from U-series dating of 44 sulfide samples collected by manned submersible from between the Mothra Field in the south to Sasquatch in the north. Samples are dated using 226Ra/Ba ratios from hydrothermal barite that precipitates along with the sulfide minerals. Most samples have been collected from within or near the active vent fields. Fifteen samples from the Main Endeavour Field (MEF) show a spectrum of ages from present to 2,430 years old, indicating that this field has been continuously active for at least ~2,400 years. MEF appears to be oldest currently active field. This minimum value for the age of hydrothermal activity also provides a minimum age of the axial valley itself. Ages from thirteen samples from the High-Rise Field indicate continuous venting for at least the past ~1,250 years. These age data are used in conjunction with age constraints of the volcanic flows to develop an integrated volcanic, hydrothermal and tectonic history of the Endeavour Segment. The total volume of hydrothermal sulfide within the axial valley, determined from high-resolution bathymetry, is used in conjunction with the age constraints of the sulfide material to determine the mass accumulation rates of sulfide along the Endeavour Segment. These data can be used to calibrate the efficiency of sulfide deposition from the hydrothermal vents, and provide a time-integrated history of heat, fluid and chemical fluxes at the ridge-segment scale. The comparison of time-integrated rates with

  9. Hydrothermal Biogeochemistry

    NASA Astrophysics Data System (ADS)

    Shock, E.; Havig, J.; Windman, T.; Meyer-Dombard, D.; Michaud, A.; Hartnett, H.

    2006-12-01

    Life in hot spring ecosystems is confronted with diverse challenges, and the responses to those challenges have dynamic biogeochemical consequences over narrow spatial and temporal scales. Within meters along hot spring outflow channels at Yellowstone, temperatures drop from boiling, and the near-boiling conditions of hot chemolithotrophic communities, to those that permit photosynthesis and on down to conditions where nematodes and insects graze on the edges of photosynthetic mats. Many major and trace element concentrations change only mildly in the water that flows through the entire ecosystem, while concentrations of other dissolved constituents (oxygen, sulfide, ammonia, total organic carbon) increase or decrease dramatically. Concentrations of metals and micronutrients range from toxic to inadequate for enzyme synthesis depending on the choice of hot spring. Precipitation of minerals may provide continuous growth of microbial niches, while dissolution and turbulent flow sweeps them away. Consequently, microbial communities change at the meter scale, and even more abruptly at the photosynthetic fringe. Isotopic compositions of carbon and nitrogen in microbial biomass reflect dramatic and continuous changes in metabolic strategies throughout the system. Chemical energy sources that support chemolithotrophic communities can persist at abundant or useless levels, or change dramatically owing to microbial activity. The rate of temporal change depends on the selection of hot spring systems for study. Some have changed little since our studies began in 1999. Others have shifted by two or more units in pH over several years, with corresponding changes in other chemical constituents. Some go through daily or seasonal desiccation cycles, and still others exhibit pulses of changing temperature (up to 40°C) within minutes. Taken together, hydrothermal ecosystems provide highly manageable opportunities for testing how biogeochemical processes respond to the scale of

  10. Distribution, activity and function of short-chain alkane degrading phylotypes in hydrothermal vent sediments

    NASA Astrophysics Data System (ADS)

    Adams, M. M.; Joye, S. B.; Hoarfrost, A.; Girguis, P. R.

    2012-12-01

    Global geochemical analyses suggest that C2-C4 short chain alkanes are a common component of the utilizable carbon pool in deep-sea sediments worldwide and have been found in diverse ecosystems. From a thermodynamic standpoint, the anaerobic microbial oxidation of these aliphatic hydrocarbons is more energetically yielding than the anaerobic oxidation of methane (AOM). Therefore, the preferential degradation of these hydrocarbons may compete with AOM for the use of oxidants such as sulfate, or other potential oxidants. Such processes could influence the fate of methane in the deep-sea. Sulfate-reducing bacteria (SRB) from hydrocarbon seep sediments of the Gulf of Mexico and Guaymas Basin have previously been enriched that anaerobically oxidize short chain alkanes to generate CO2 with the preferential utilization of 12C-enriched alkanes (Kniemeyer et al. 2007). Different temperature regimens along with multiple substrates were tested and a pure culture (deemed BuS5) was isolated from mesophilic enrichments with propane or n-butane as the sole carbon source. Through comparative sequence analysis, strain BuS5 was determined to cluster with the metabolically diverse Desulfosarcina / Desulfococcus cluster, which also contains the SRB found in consortia with anaerobic, methane-oxidizing archaea in seep sediments. Enrichments from a terrestrial, low temperature sulfidic hydrocarbon seep also corroborated that propane degradation occurred with most bacterial phylotypes surveyed belonging to the Deltaproteobacteria, particularly Desulfobacteraceae (Savage et al. 2011). To date, no microbes capable of ethane oxidation or anaerobic C2-C4 alkane oxidation at thermophilic temperature have been isolated. The sediment-covered, hydrothermal vent systems found at Middle Valley (Juan de Fuca Ridge, eastern Pacific Ocean) are a prime environment for investigating mesophilic to thermophilic anaerobic oxidation of short-chain alkanes, given the elevated temperatures and dissolved

  11. Cinnabar, arsenian pyrite and thallium-enrichment in active shallow submarine hydrothermal vents at Paleochori Bay, Milos Island, Greece

    NASA Astrophysics Data System (ADS)

    Kati, Marianna; Voudouris, Panagiotis; Valsami-Jones, Eugenia; Magganas, Andreas; Baltatzis, Emmanouil; Kanellopoulos, Christos; Mavrogonatos, Constantinos

    2015-04-01

    We herein report the discovery of active cinnabar-depositing hydrothermal vents in a submarine setting at Paleochori Bay, within the offshore southeastern extension of the Milos Island Geothermal Field, South Aegean Active Volcanic Arc. Active, low temperature (up to 115 °C) hydrothermal venting through volcaniclastic material has led to a varied assemblage of sulfide and alteration mineral phases in an area of approximately 1 km2. Our samples recovered from Paleochori Bay are hydrothermal edifices composed of volcaniclastic detrital material cemented by pyrite, or pure sulfide (mainly massive pyrite) mounts. Besides pyrite and minor marcasite, the hydrothermal minerals include cinnabar, amorphous silica, hydrous ferric oxides, carbonates (aragonite and calcite), alunite-jarosite solid solution and Sr-rich barite. Among others, growth textures, sieve-textured pyrite associated with barite, alunite-jarosite solid solution and hydrous ferric oxides rims colloform-banded pyrite layers. Overgrowths of arsenian pyrite layers (up to 3.2 wt. % As and/or up to 1.1 wt. % Mn) onto As-free pyrite indicate fluctuation in As content of the hydrothermal fluid. Mercury, in the form of cinnabar, occurs in up to 5 μm grains within arsenian pyrite layers, usually forming distinct cinnabar-enriched micro-layers. Hydrothermal Sr-rich barite (barite-celestine solid solution), pseudocubic alunite-jarosite solid solution and Mn- and Sr-enriched carbonates occur in various amounts and closely associated with pyrite and/or hydrous ferric oxides. Thallium-bearing sulfides and/or sulfosalts were not detected during our study; however, hydrous ferric oxides show thallium content of up to 0.5 wt. % Tl. The following scenarios may have played a role in pyrite precipitation at Paleochori: (a) H2S originally dissolved in the deep fluid but separated upon boiling could have reacted with oxygenated seawater under production of sulphuric acid, thus causing leaching and dissolution of primary iron

  12. Large-scale fabrication of In2S3 porous films via one-step hydrothermal process.

    PubMed

    Chen, Fei; Deng, Dan; Lei, Yinlin

    2013-10-01

    Large-scale indium sulfide (In2S3) porous films were fabricated via a facile one-step and non-template hydrothermal process using L-cysteine as a capping agent. The impact of reaction conditions such as reaction time, temperatures, and capping agents on the synthesis of the In2S3 porous films were studied. The morphology, structure, and phase composition of In2S3 porous films were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The formation process and the optical property of the In2S3 porous films were also evaluated.

  13. Characteristics of Hydrothermal Mineralization in Ultraslow Spreading Ridges

    NASA Astrophysics Data System (ADS)

    Zhou, H.; Yang, Q.; Ji, F.; Dick, H. J.

    2014-12-01

    Hydrothermal activity is a major component of the processes that shape the composition and structure of the ocean crust, providing a major pathway for the exchange of heat and elements between the Earth's crust and oceans, and a locus for intense biological activity on the seafloor and underlying crust. In other hand, the structure and composition of hydrothermal systems are the result of complex interactions between heat sources, fluids, wall rocks, tectonic controls and even biological processes. Ultraslow spreading ridges, including the Southwest Indian Ridge, the Gakkel Ridge, are most remarkable end member in plate-boundary structures (Dick et al., 2003), featured with extensive tectonic amagmatic spreading and frequent exposure of peridotite and gabbro. With intensive surveys in last decades, it is suggested that ultraslow ridges are several times more effective than faster-spreading ridges in sustaining hydrothermal activities. This increased efficiency could attributed to deep mining of heat and even exothermic serpentinisation (Baker et al., 2004). Distinct from in faster spreading ridges, one characteristics of hydrothermal mineralization on seafloor in ultraslow spreading ridges, including the active Dragon Flag hydrothermal field at 49.6 degree of the Southwest Indian Ridge, is abundant and pervasive distribution of lower temperature precipitated minerals ( such as Fe-silica or silica, Mn (Fe) oxides, sepiolite, pyrite, marcasite etc. ) in hydrothermal fields. Structures formed by lower temperature activities in active and dead hydrothermal fields are also obviously. High temperature precipitated minerals such as chalcopyrite etc. are rare or very limited in hydrothermal chimneys. Distribution of diverse low temperature hydrothermal activities is consistence with the deep heating mechanisms and hydrothermal circulations in the complex background of ultraslow spreading tectonics. Meanwhile, deeper and larger mineralization at certain locations along the

  14. Vent fluid chemistry of the Rainbow hydrothermal system (36°N, MAR): Phase equilibria and in situ pH controls on subseafloor alteration processes

    NASA Astrophysics Data System (ADS)

    Seyfried, W. E., Jr.; Pester, Nicholas J.; Ding, Kang; Rough, Mikaella

    2011-03-01

    The Rainbow hydrothermal field is located at 36°13.8'N-33°54.15'W at 2300 m depth on the western flank of a non-volcanic ridge between the South AMAR and AMAR segments of the Mid-Atlantic Ridge. The hydrothermal field consists of 10-15 active chimneys that emit high-temperature (˜365 °C) fluid. In July 2008, vent fluids were sampled during cruise KNOX18RR, providing a rich dataset that extends in time information on subseafloor chemical and physical processes controlling vent fluid chemistry at Rainbow. Data suggest that the Mg concentration of the hydrothermal end-member is not zero, but rather 1.5-2 mmol/kg. This surprising result may be caused by a combination of factors including moderately low dissolved silica, low pH, and elevated chloride of the hydrothermal fluid. Combining end-member Mg data with analogous data for dissolved Fe, Si, Al, Ca, and H 2, permits calculation of mineral saturation states for minerals thought appropriate for ultramafic-hosted hydrothermal systems at temperatures and pressures in keeping with constraints imposed by field observations. These data indicate that chlorite solid solution, talc, and magnetite achieve saturation in Rainbow vent fluid at a similar pH (T,P) (400 °C, 500 bar) of approximately 4.95, while higher pH values are indicated for serpentine, suggesting that serpentine may not coexist with the former assemblage at depth at Rainbow. The high Fe/Mg ratio of the Rainbow vent fluid notwithstanding, the mole fraction of clinochlore and chamosite components of chlorite solid solution at depth are predicted to be 0.78 and 0.22, respectively. In situ pH measurements made at Rainbow vents are in good agreement with pH (T,P) values estimated from mineral solubility calculations, when the in situ pH data are adjusted for temperature and pressure. Calculations further indicate that pH (T,P) and dissolved H 2 are extremely sensitive to changes in dissolved silica owing to constraints imposed by chlorite solid solution

  15. Hydrothermal synthesis of ZTO/graphene nanocomposite with excellent photocatalytic activity under visible light irradiation.

    PubMed

    Ben Ali, Monaam; Yolcu, Haci Hasan; Elhouichet, Habib; Sieber, Brigitte; Addad, Ahmed; Boussekey, Luc; Moreau, Myriam; Férid, Mokhtar; Szunerits, Sabine; Boukherroub, Rabah

    2016-07-01

    A facile and efficient one-step hydrothermal approach for the synthesis of Zn2SnO4 nanoparticles/reduced graphene oxide (ZTO/rGO) nanocomposites using zinc acetate, tin chloride and graphene oxide (GO) as precursors, and sodium hydroxide as reducing agent has been developed. This approach allows simultaneous reduction of GO and growth of spinel ZTO nanoparticles (NPs) on the rGO sheets. The morphology and microstructure characterizations of ZTO/rGO nanocomposites revealed that this method leads to close interfacial contact of ZTO NPs and rGO and efficient dispersion of ZTO NPs on the surface of rGO sheets. The photocatalytic activity of the ZTO/rGO nanocomposite was investigated for the reduction of rhodamine B under visible light irradiation. Compared to pure ZTO NPs, ZTO/rGO nanocomposite exhibited superior photocatalytic activity with a full degradation of rhodamine B within 15min. The enhanced photocatalytic performance of ZTO/rGO was mainly attributed to excellent electron trapping and effective adsorption properties of rGO.

  16. Anomalous quartz from the Roter Kamm impact crater, Namibia: Evidence for post-impact hydrothermal activity

    SciTech Connect

    Koeberl, C. Univ. of Vienna ); Fredriksson, K. ); Goetzinger, M. ); Reimold, W.U. )

    1989-08-01

    Centimeter-sized quartz pebbles have been found on the rim of the Roter Kamm impact crater. The Roter Kamm crater has a diameter of about 2.5 km and is situated in the Namib Desert, SWA/Namibia. Because of the sand coverage, impact products are exposed exclusively in the form of ejecta on the crater rim. The quartz pebbles were found close to the main deposits of the impact breccias and show signs of wind abrasion. Thin sections revealed that the pebbles consist of individual quartz domains that are up to 1 mm in size. Under crossed nicols (polarized light), all individual domains show extinction almost simultaneously within {plus minus}2{degree}, which is a rare phenomenon. Microprobe studies, neutron activation analyses, and X-ray diffractometry confirmed that the material consists of pure quartz. The quartz contains three different types of fluid inclusions: primary inclusions that record the formation conditions of the quartz, very small (<1 {mu}m) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. Freezing point depression measurements of the primary inclusions indicate fluid salinities between 18.3 and 19.6 wt% NaCl. Homogenization temperatures (T{sub h}) for the primary inclusions range from 165 to 250{degree}C. The quartz and the primary inclusions may provide evidence for a post-impact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  17. Acid-Base Behavior in Hydrothermal Processing of Wastes - Final Report

    SciTech Connect

    Johnston, K.; Rossky, P.

    2000-12-01

    A major obstacle to development of hydrothermal oxidation technology has been a lack of scientific knowledge of chemistry in hydrothermal solution above 350 C, particularly acid-base behavior, and transport phenomena, which is needed to understand corrosion, metal-ion complexation, and salt precipitation and recovery. Our objective has been to provide this knowledge with in situ UV-visible spectroscopic measurements and fully molecular computer simulation. Our recent development of relatively stable organic UV-visible pH indicators for supercritical water oxidation offers the opportunity to characterize buffers and to monitor acid-base titrations. These results have important implications for understanding reaction pathways and yields for decomposition of wastes in supercritical water.

  18. Seawater bicarbonate removal during hydrothermal circulation

    NASA Astrophysics Data System (ADS)

    Proskurowski, G. K.; Seewald, J.; Sylva, S. P.; Reeves, E.; Lilley, M. D.

    2013-12-01

    High temperature fluids sampled at hydrothermal vents represent a complex alteration product of water-rock reactions on a multi-component mixture of source fluids. Sources to high-temperature hydrothermal samples include the 'original' seawater present in the recharge limb of circulation, magmatically influenced fluids added at depth as well as any seawater entrained during sampling. High-temperature hydrothermal fluids are typically enriched in magmatic volatiles, with CO2 the dominant species, characterized by concentrations of 10's-100's of mmol/kg (1, 2). Typically, the high concentration of CO2 relative to background seawater bicarbonate concentrations (~2.3 mmol/kg) obscures a full analysis of the fate of seawater bicarbonate during high-temperature hydrothermal circulation. Here we present data from a suite of samples collected over the past 15 years from high-temperature hydrothermal vents at 9N, Endeavour, Lau Basin, and the MAR that have endmember CO2 concentrations less than 10 mmol/kg. Using stable and radiocarbon isotope measurements these samples provide a unique opportunity to examine the balance between 'original' seawater bicarbonate and CO2 added from magmatic sources. Multiple lines of evidence from multiple hydrothermal settings consistently points to the removal of ~80% of the 'original' 2.3 mmol/kg seawater bicarbonate. Assuming that this removal occurs in the low-temperature, 'recharge' limb of hydrothermal circulation, this removal process is widely occurring and has important contributions to the global carbon cycle over geologic time. 1. Lilley MD, Butterfield DA, Lupton JE, & Olson EJ (2003) Magmatic events can produce rapid changes in hydrothermal vent chemistry. Nature 422(6934):878-881. 2. Seewald J, Cruse A, & Saccocia P (2003) Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity. Earth and Planetary Science Letters 216(4):575-590.

  19. Potential of the hydrothermal carbonization process for the degradation of organic pollutants.

    PubMed

    Weiner, Barbara; Baskyr, Igor; Poerschmann, Jürgen; Kopinke, Frank-Dieter

    2013-07-01

    The degree of degradation of 12 organic compounds from various classes, comprising of pharmaceuticals, pesticides, and industrial chemicals, was analyzed after hydrothermal treatment at 200°C for 4 or 16h, or 255°C for 16h. The reactions were conducted in water, aqueous H2SO4, or sucrose solution in aqueous H2SO4 as a representative matrix of hydrothermal carbonization (HTC) of wet biomasses. The impact of the sucrose-matrix, which formed during the HTC reaction as a solid hydrochar material and a complex pattern of dissolved organic matter in the aqueous phase, was found to be insignificant for the degree of conversion of most compounds. On the contrary, the degree of degradation of 2,6-dinitrotoluene, 2-chloronaphthalene and 3-chlorobiphenyl was enhanced when biomass was present. At high temperatures most of the pollutants were converted except for ibuprofen and chlorinated aromatics. Hydrothermal treatment of β-hexachlorocyclohexane and 4,4'-dichlorodiphenyltrichloroethane led to the formation of stable chlorinated aromatic intermediates.

  20. Synthesis and electrochemical performance of Ti3C2Tx with hydrothermal process

    NASA Astrophysics Data System (ADS)

    Wang, Libo; Zhang, Heng; Wang, Bo; Shen, Changjie; Zhang, Chuanxiang; Hu, Qianku; Zhou, Aiguo; Liu, Baozhong

    2016-09-01

    In this study, a simple hydrothermal method has been developed to prepare Ti3C2Tx from Ti3AlC2 as a high-performance electrode material for supercapacitors. This method is environmentally friendly and has a low level of danger. The morphology and structure of the Ti3C2Tx can be controlled by hydrothermal reaction time, temperature and NH4F amounts. The prepared Ti3C2Tx was characterized by X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and Brunauer-Emmet-Teller. The results show that the prepared Ti3C2Tx is terminated by O, OH, and F groups. The electrochemical properties of the Ti3C2Tx sample exhibit specific capacitance up to 141 Fcm-3 in 3 M KOH aqueous electrolyte, and even after 1000 cycles, no significant degradation of the volumetric capacitance was observed. These results indicate that the Ti3C2Tx material prepared by this hydrothermal method can be used in high performance supercapacitors.

  1. Integrated Geoscience Studies in the Greater Yellowstone Area - Volcanic, Tectonic, and Hydrothermal Processes in the Yellowstone Geoecosystem

    USGS Publications Warehouse

    Morgan, Lisa A.

    2007-01-01

    Yellowstone National Park, rimmed by a crescent of older mountainous terrain, has at its core the Quaternary Yellowstone Plateau, an undulating landscape shaped by forces of volcanism, tectonism, and later glaciation. Its spectacular hydrothermal systems cap this landscape. From 1997 through 2003, the United States Geological Survey Mineral Resources Program conducted a multidisciplinary project of Yellowstone National Park entitled Integrated Geoscience Studies of the Greater Yellowstone Area, building on a 130-year foundation of extensive field studies (including the Hayden survey of 1871, the Hague surveys of the 1880s through 1896, the studies of Iddings, Allen, and Day during the 1920s, and NASA-supported studies starting in the 1970s - now summarized in USGS Professional Paper 729 A through G) in this geologically dynamic terrain. The project applied a broad range of scientific disciplines and state-of-the-art technologies targeted to improve stewardship of the unique natural resources of Yellowstone and enable the National Park Service to effectively manage resources, protect park visitors from geologic hazards, and better educate the public on geologic processes and resources. This project combined a variety of data sets in characterizing the surficial and subsurface chemistry, mineralogy, geology, geophysics, and hydrothermal systems in various parts of the park. The sixteen chapters presented herein in USGS Professional Paper 1717, Integrated Geoscience Studies in the Greater Yellowstone Area - Volcanic, Tectonic, and Hydrothermal Processes in the Yellowstone Geoecosystem, can be divided into four major topical areas: (1) geologic studies, (2) Yellowstone Lake studies, (3) geochemical studies, and (4) geophysical studies. The geologic studies include a paper by Ken Pierce and others on the influence of the Yellowstone hotspot on landscape formation, the ecological effects of the hotspot, and the human experience and human geography of the greater

  2. Permeability Reduction in Passively Degassing Seawater-dominated Volcanic-hydrothermal systems: Processes and Perils on Raoul Island, Kermadecs (NZ)

    NASA Astrophysics Data System (ADS)

    Christenson, B. W.; Reyes, A. G.

    2014-12-01

    The 2006 eruption from Raoul Island occurred apparently in response to local tectonic swarm activity, but without any precursory indication of volcanic unrest within the hydrothermal system on the island. The eruption released some 200 T of SO2, implicating the involvement of a deep magmatic vapor input into the system during/prior to the event. In the absence of any recognized juvenile material in the eruption products, previous explanations for this eruptive event focused on this vapor being a driving force for the eruption. In 2004, at least 80 T/d of CO2 was escaping from the hydrothermal system, but mainly through areas that did not correspond to the 2006 eruption vents. The lack of a pre-eruptive hydrothermal system response related to the seismic event in 2006 can be explained by the presence of a hydrothermal mineralogic seal in the vent area of the volcano. Evidence for the existence of such a seal was found in eruption deposits in the form of massive fracture fillings of aragonite, calcite and anhydrite. Fluid inclusion homogenization temperatures in these phases range from ca. 140 °C to 220 °C which, for pure water indicate boiling point depths of between 40 and 230 m assuming a cold hydrostatic pressure constraint. Elevated pressures behind this seal are consistent with the occurrence of CO2 clathrates in some inclusion fluids, indicating CO2 concentrations approaching 1 molal in the parent fluids. Reactive transport modeling of magmatic volatile inputs into what is effectively a seawater-dominated hydrothermal system provide valuable insights into seal formation. Carbonate mineral phases ultimately come to saturation along this flow path, but we suggest that focused deposition of the observed massive carbonate seal is facilitated by near-surface boiling of these CO2-enriched altered seawaters, leading to large degrees of supersaturation which are required for the formation of aragonite. As the seal grew and permeability declined, pore pressures

  3. Active braze process

    SciTech Connect

    Levine, I.L.; Pike, R.A.

    1990-11-02

    Active metal bonding using Cusil (silver-copper) braze alloys is a well established method used at GE Neutron Devices (GEND) for bonding metal to metal, metal to ceramics, and ceramics to ceramics. However, there are many instances in which using a silver alloy for bonding is undesirable (e.g., in vacuum tube envelopes, or where sequential braze steps at different temperatures are required to complete an assembly). The Material and Processes Laboratory at GEND has discovered a new method of active brazing with non-silver alloys which has proved especially successful in ceramic-to-ceramic joints. This method has the added advantage of eliminating several steps which are required in conventional bonding techniques. 2 figs., 10 tabs.

  4. State of the hydrothermal activity of Soufrière of Guadeloupe volcano inferred by VLF surveys

    NASA Astrophysics Data System (ADS)

    Zlotnicki, J.; Vargemezis, G.; Mille, A.; Bruère, F.; Hammouya, G.

    2006-04-01

    La Soufrière (1467 m) is the active island arc volcano of Guadeloupe Island in the Lesser Antilles arc. Its historical eruptions are more or less violent phreatic outbursts the last of which, in 1976-1977, led to the evacuation of nearly 70 000 persons. The subsurface structure of the volcano consists of calderas, craters, and avalanche amphitheatres nested within the composite pile of eruptive products. Since the last magmatic eruption, dated ca. 1440 AD, the four phreatic eruptions have developed radial fractures on Soufrière dome favouring the development of a huge active hydrothermal system emphasized by a tropical environment. After the eruptions, the thermal state and the stable ground water flow are completely disorganised during several years during which the slow mineralization of rocks is becoming again preponderant. Sealing of fractures and decay of rocks permeability act as a cap for upward thermal transfers. Therefore Soufrière dome operates as a valve, resealing the hydrothermal system underlying the volcano thus providing over pressurization that could lead to the next phreatic eruption. In 1992 new small seismic swarms have appeared. Several of them are recorded every year while the emission of acid gas slowly increases. In order to recognise the superficial electrical resistive and conductive zones (less than 100 m depth) as well as the cavities on Soufrière volcano, we have made Very Low Frequency (VLF) surveys in 2000. Electrical conductive zones are clearly associated with major radial faults starting from the summit in which the hydrothermal activity takes place. In the continuation of these active hydrothermal fractures hot springs are located down slope. Conversely some of the resistive zones are associated with inactive clayed and sealed or opened faults. The distribution of the conductive zones allows detailing the state of the superficial part of the hydrothermal system of La Soufrière. The distribution of vertical clayed zones

  5. Hydrothermal REE and Zr Ore Forming Processes in Peralkaline Granitic Systems

    NASA Astrophysics Data System (ADS)

    Gysi, A. P.

    2015-12-01

    Anorogenic peralkaline igneous systems display extreme enrichment of REE and Zr with a hydrothermal overprint leading to post-magmatic metal mobilization. Strange Lake in Canada, for example, is a mid-Proterozoic peralkaline granitic intrusion and host to a world-class REE-Zr deposit with >50 Mt ore (>1.5 wt.% REE and >3 wt.% Zr). In contrast to porphyry systems, peralkaline systems are poorly understood and hydrothermal metal mobilization models are only in the early stage of their development. This is partly due to the paucity of thermodynamic data for REE-bearing minerals and aqueous species, and the complexity of the hydrothermal fluids (enrichment of F, P and Cl), which make it difficult to develop thermodynamic models of metal partitioning. This study aims to show the link between alteration stages and metal mobilization using Strange Lake as a natural laboratory and combine these observations with numerical modeling. Four types of alteration were recognized at Strange Lake: i) alkali (i.e. K and Na) metasomatism related to interaction with NaCl-bearing orthomagmatic fluids, ii) acidic alteration by HCl-HF-bearing fluids originating from the pegmatites followed by iii) aegirinization of the border of the pegmatites and surrounding granites and by iv) pervasive Ca-F-metasomatism. The acidic alteration accounts for most of the hydrothermal metal mobilization in and outward from the pegmatites, whereas the Ca-F-metasomatism led to metal deposition and resulted from interaction of an acidic F-rich fluid with a Ca-bearing fluid. Numerical simulations of fluid-rock reactions with saline HCl-HF-bearing fluids at 400 °C to 250 °C indicate that temperature, availability of F/Cl and pH limit the mobility of Zr and REE. Fluids with pH <2 led to the formation of quartz and fluorite in the core of the pegmatites and to an increase in the stability of REE chloride species favorable for REE mobilization. The mobilization of Zr was favored at low temperature with the

  6. Synthesis and Enhanced Photocatalytic Activity of Ce-Doped Zinc Oxide Nanorods by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Aisah, N.; Gustiono, D.; Fauzia, V.; Sugihartono, I.; Nuryadi, R.

    2017-02-01

    Zinc oxide (ZnO) is a n-type semiconductor material which has a wide direct band gap energy of ∼ 3.3 eV, and other interesting optical properties, hence it’s potentially applied to various fields such as electronics, optoelectronics, sensors, photonic devices, and also photocatalyst. Dopant in ZnO nanostructures is an effective way to improve ZnO’s structural properties in various applications. In this study, undoped and Ce doped ZnO nanorods were synthesized on ITO coated glass substrates by ultrasonic spray pyrolysis for seeding deposition and hydrothermal methods at a temperature of 95 0C for 2 hours for growth. X-ray diffraction, field emission scanning electron microscopy (FESEM), UV-VIS and Photoluminescence spectroscopy were used to characterize the crystal structure, surface morphology and optical properties of ZnO nanorods and the photocatalytic activity test for methylene blue degradation. The experimental results showed that 3% Cerium dopant has produced hexagonal morphology ZnO nanorod growing more uniform on (002) crystal planes, increased the intensity of ultraviolet absorbance thereby increase the degradation speed of methylene blue.

  7. Evaluation of the US DOE's conceptual model of hydrothermal activity at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Dublyansky, Y. V.

    2014-08-01

    A unique conceptual model describing the conductive heating of rocks in the thick unsaturated zone of Yucca Mountain, Nevada by a silicic pluton emplaced several kilometers away is accepted by the US Department of Energy (DOE) as an explanation of the elevated depositional temperatures measured in fluid inclusions in secondary fluorite and calcite. Acceptance of this model allowed the DOE to keep from considering hydrothermal activity in the performance assessment of the proposed high-level nuclear waste disposal facility. The evaluation presented in this paper shows that no computational modeling results have yet produced a satisfactory match with the empirical benchmark data, specifically with age and fluid inclusion data that indicate high temperatures (up to ca. 80 °C) in the unsaturated zone of Yucca Mountain. Auxiliary sub-models complementing the DOE model, as well as observations at a natural analog site, have also been evaluated. Summarily, the model cannot be considered as validated. Due to the lack of validation, the reliance on this model must be discontinued and the appropriateness of decisions which rely on this model must be re-evaluated.

  8. Discovery of sublacustrine hydrothermal activity and associated massive sulfides and hydrocarbons in the north Tanganyika trough, East African Rift

    SciTech Connect

    Tiercelin, J.J.; Mondeguer, A. ); Thouin, C. ); Kalala, T. )

    1989-11-01

    Massive sulfides and carbonate mineral deposits associated with sublacustrine thermal springs were recently discovered along the Zaire side of the north Tanganyika trough, western branch of the East African Rift. This hydrothermal activity, investigated by scuba diving at a maximum depth of 20 m, is located at the intersection of major north-south normal faults and northwest-southeast faults belonging to the Tanganyika-Rukwa-Malawi (TRM) strike-slip fault zone. The preliminary results presented here come from analyses of sulfide deposits, hydrothermal fluids, and associated hydrocarbons that result from geothermal activity in this part of the East African Rift filled by a thick pile of sediment, the north Tanganyika trough.

  9. P-doped TiO2 with superior visible-light activity prepared by rapid microwave hydrothermal method

    NASA Astrophysics Data System (ADS)

    Niu, Jinfen; Lu, Pan; Kang, Mei; Deng, Kunfa; Yao, Binghua; Yu, Xiaojiao; Zhang, Qian

    2014-11-01

    Phosphorous-doped anatase TiO2 powders (P-TiO2) were prepared by rapid microwave hydrothermal method. The resulting materials were characterized by XRD, SEM, XPS, DRS and N2 adsorption. P-doping decreased the band gap and enlarged the surface area of P-doped samples than that of undoped TiO2 samples. Therefore, the photocatalytic degradation of methyl blue (MB) and tetracycline hydrochloride (Tc) experiments showed that the P-TiO2 catalysts, especially the two-steps-controlling products P-TiO2-2, exhibited higher degradation efficiency than the undoped TiO2 and commercial P25 under visible-light irradiation. Hydroxyl radicals (rad OH) have been confirmed to be the active species during the photocatalytic oxidation reaction. The microwave hydrothermal method confirms to be very suitable for the synthesis of superior visible-light activity P-doped samples.

  10. Hydrothermal carbonization and torrefaction of grape pomace: a comparative evaluation.

    PubMed

    Pala, Mehmet; Kantarli, Ismail Cem; Buyukisik, Hasan Baha; Yanik, Jale

    2014-06-01

    Grape pomace was treated by hydrothermal carbonization (sub-critical water, 175-275°C) and torrefaction (nitrogen atmosphere, 250 and 300°C), with mass yield of solid product (char) ranging between 47% and 78%, and energy densification ratio to 1.42-1.15 of the original feedstock. The chars were characterised with respect to their fuel properties, morphological and structural properties and combustion characteristics. The hydrothermal carbonization produced the char with greater energy density than torrefaction. The chars from torrefaction were found to be more aromatic in nature than that from hydrothermal carbonization. Hydrothermal carbonization process produced the char having high combustion reactivity. Most interesting was the finding that aqueous phase from hydrothermal carbonization had antioxidant activity. The results obtained in this study showed that HTC appears to be promising process for a winery waste having high moisture content.

  11. Soluble inhibitors generated during hydrothermal pretreatment of oil palm mesocarp fiber suppressed the catalytic activity of Acremonium cellulase.

    PubMed

    Zakaria, Mohd Rafein; Hirata, Satoshi; Fujimoto, Shinji; Ibrahim, Izzudin; Hassan, Mohd Ali

    2016-01-01

    Oil palm mesocarp fiber was subjected to hydrothermal pretreatment under isothermal and non-isothermal conditions. The pretreated slurries were separated by filtration, pretreated liquids and solids were characterized. An enzymatic digestibility study was performed for both pretreated slurries and solids to understand the effect of soluble inhibitors generated during the pretreatment process. The highest glucose yield obtained from pretreated slurries was 70.1%, and gradually decreased with higher pretreatment severities. The highest glucose yield obtained in pretreated solids was 100%, after pretreatment at 210°C for 20min. In order to study the inhibitory effects of compounds generated during pretreatment with cellulase, technical grade solutions that mimic the pretreated liquid were prepared and their effect on Acremonium cellulase activity was monitored using Avicel. Xylo-oligomers and tannic acid were identified as powerful inhibitors of Acremonium cellulase, and the lowest hydrolysis rate of Avicel of 0.18g/g-glucose released/L/h was obtained from tannic acid.

  12. Nitrogen-doped graphene/ZnSe nanocomposites: hydrothermal synthesis and their enhanced electrochemical and photocatalytic activities.

    PubMed

    Chen, Ping; Xiao, Tian-Yuan; Li, Hui-Hui; Yang, Jing-Jing; Wang, Zheng; Yao, Hong-Bin; Yu, Shu-Hong

    2012-01-24

    Nitrogen-doped graphene (GN) has great potential applications in many fields because doping with nitrogen can alter the electrical properties of graphene. It is still a challenge to develop a convenient method for synthesis of GN sheets. In this paper, we first report the synthesis of a nitrogen-doped graphene/ZnSe nanocomposite (GN-ZnSe) by a one-pot hydrothermal process at low temperature using graphene oxide nanosheets and [ZnSe](DETA)(0.5) nanobelts as precursors. ZnSe nanorods composed of ZnSe nanoparticles were found to deposit on the surface of the GN sheets. The results demonstrated that [ZnSe](DETA)(0.5) nanobelts were used not only as the source of ZnSe nanoparticles but also as the nitrogen source. Interestingly, it was found that the as-prepared nanocomposites exhibit remarkably enhanced electrochemical performance for oxygen reduction reaction and photocatalytic activities for the bleaching of methyl orange dye under visible-light irradiation. This facile and catalyst-free approach for depositing ZnSe nanoparticles onto the graphene sheets may provide an alternative way for preparation of other nanocomposites based on GN sheets under mild conditions, which show their potential applications in wastewater treatment, fuel cells, energy storage, nanodevices, and so on.

  13. Mixing vs Boiling process in a shallow submarine hydrothermal system of Bahía Concepción, Mexico

    NASA Astrophysics Data System (ADS)

    Villanueva Estrada, R.; Prol-Ledesma, R.; Rodríguez, A.; Canet, C.; Torres, I.; González, E.

    2009-12-01

    In this paper we use geochemical modeling and fluid inclusions to support the hypothesis that the main process that undergoes the fluid discharged by submarine vents in Bahia Concepcion is mixing rather than boiling. Mixing modeling of two different fluids: a high salinity fluid that is mixed with a deep thermal fluid of meteoric origin indicate that the thermal water responsible for the formation of the thermal EM of Bahía Concepción is composed by 20-30% of a HDF and 70-80% of a hot DF of meteoric origin. Boiling would be an alternate process; however, fluid inclusions petrography and microthermometry reveal no boiling evidence present in the samples, as breccias, bladed calcite, or coexisting liquid-rich and vapor-rich inclusions. Furthermore, the salinity of pseudosecondary and secondary fluid inclusions is similar to seawater. The mixing model is consistent with fluid inclusion data, which provide evidence that two different hydrothermal fluids are involved in barite deposition at veins related to the submarine manifestations of Bahía Concepción: a low salinity fluid (139°C and 3.2 wt % NaCl eq) and HSF (129°C and 10.6 wt % NaCl eq.) The trend observed between high- to low-salinity fluids shows the occurrence of mixing processes between both hydrothermal fluids.

  14. Microearthquakes at the active Trans-Atlantic Geotraverse (TAG) hydrothermal mound, Mid-Atlantic Ridge, 26°08'N

    NASA Astrophysics Data System (ADS)

    Pontbriand, C.; Reves-Sohn, R. A.

    2010-12-01

    A small 200 m aperture network of five ocean bottom seismometers around the periphery the active TAG hydrothermal mound on the Mid-Atlantic Ridge (26°08’N) detected microearthquake events that may be associated with the subsurface hydraulics of the massive hydrothermal deposit. Seismic data were sampled at 100 Hz for a period of eight months spanning June, 2003 to February, 2004, during which time 24,191 locatable events were detected. Microearthquake hypocenters are concentrated within a 300 m radius of the sulfide mound in the top 250 m of crust, and exhibit a conical shape with the deepest events beneath the mound center. Event rates are steady at 180 events per day at the beginning of the study period and decline slightly to 116 events per day after whale calls elevate background noise levels about 2/3 of the way through the deployment. The mean local magnitude of events is -1.2 with a range of -2.9≦ML≦0.3. We suggest that events may be largely due to hydraulic fracturing of clogged flow conduits in the mineral deposit, which provides the possibility of using the microearthquake data to constrain subsurface flow parameters and the permeability structure of the active TAG deposit. Figure: A bathymetric map of the TAG area depicts a small aperture network of 5 ocean bottom seismometers (white triangles) around the periphery of the active TAG hydrothermal mound. High resolution bathymetry is from Roman and Singh, 2005.

  15. A Fluorescein Tracer Release Experiment in the Hydrothermally Active Crater of Vailulu'u Volcano, Samoa

    NASA Astrophysics Data System (ADS)

    Hart, S. R.; Staudigel, H.; Workman, R.; Koppers, A.; Girard, A.

    2001-12-01

    Vailulu'u (Rockne) volcano marks the active end of the Samoa hotspot chain. The volcano is 4400 meters high, with a summit crater 2000 meters wide by 400 meters deep and summit peaks reaching to within 600 meters of the sea surface. The crater is hydrothermally active, as witnessed by intense particulate concentrations in the water column (values to 1.4 NTU's), a particulate smog ``halo'' surrounding the summit and extending out many kilometers, high Mn concentrations and 3He/4He ratios (values to 3.8 ppb and 8.6 Ra, respectively), and bottom-water temperature anomalies of 0.5oC. Basalts from the crater have been dated in the range 5-50 years, and likely reflect eruptions associated with a 1995 earthquake swarm. On April 3, 2001, we released a 20 kg point-source charge of fluorescein dye 30 meters above the 975m deep crater floor. The dye was dissolved in a 180 liter mixture of propanol and water, adjusted to a density 1.3 per mil heavier than the ambient water at the release depth. Released from a rubberized bag by means of a galvanic link. First detection of the released dye was 39 hours after the deployment; the dye was in a 50 meter thick layer, with a concentration peak at 900 meters (relative to the release depth of 945m). Tracking was carried out by a CTD-based fluorometer operated in tow-yo mode from the U.S.C.G. Icebreaker Polar Sea. The detection limit was 25 picograms/gram, and the maximum detected concentration was 18,000 pg/g (if evenly dispersed in the lower 150 meters of water in the crater, the expected concentration would be approx. 130 pg/g). While the dye pool was only surveyed for 4 days due to ship-transit constraints, significant horizontal and vertical dispersion was apparent. Vertical dispersion velocities were typically 0.05 cm/sec; horizontal velocities were typically higher by a factor of 10. An approximate diapycnal or eddy diffusivity, K, can be calculated from the rate of vertical spreading of the dye layer: K = Z2/2(t-t0), where Z is

  16. The non-transform discontinuity on the Central Indian Ridge at 11°S: The transtensional basin formation and hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Pak, S. J.; Kim, H. S.; Son, J.; Kim, J.; Moon, J. W.; Son, S. K.

    2014-12-01

    The bathymetric and magnetic survey, hydrocasting and seabed sampling have been carried out in the middle portion of the Central Indian Ridge (MCIR) between 7°S and 17°S. The MCIR constitutes six first-order segments and seven second-order segments with four non-transform discontinuities (NTDs) and twelve ocean core complexes (OCCs). These segments are characterized by asymmetric accretion that corresponds to about 70% of the surveyed MCIR segment. One of the outstanding NTD in the area is a basin like NTD3-1 at 11°S (50km in length) which strike at 035°, approximately 45° oblique in a clockwise direction to the orientation of two adjoining second-order segments. The hydrothermal activity is recognized at the tips of NTD3-1. No abyssal hills paralleling to basin-shape NTD3-1 are observed. Anomalous depth of the basin, lack of positive magnetic anomaly across the basin and rare seismic activities in the basin floor suggests that extensional tectonism with a sparse volcanism is the dominant process occurring along the NTD3-1. Based on the previous researches that the counterclockwise rotation of ridge is predominant in the area, the region of NTD3-1 largely accommodates shear strain by left-lateral sense motion and consequently forms a transtensional basin, i.e., a pull-apart basin. The strong and frequent hydrothermal plume signals, and highly tectonized rocks in both tips of the NTD3-1 are reflective of the dilation zones or tensional fractures accompanied by the pull-apart basin formation. It is the first identification of a pull-apart basin associated with hydrothermal activity in the Central Indian Ridge.

  17. SeaVOICE: Sea-going Experiments to Test Potential Linkages among Sea Level Change, Ocean Ridge Volcanism, and Hydrothermal Activity.

    NASA Astrophysics Data System (ADS)

    Langmuir, C. H.; Carbotte, S. M.; Huybers, P. J.; McManus, J. F.; Mukhopadhyay, S.; Winckler, G.; Boulahanis, B.; Costa, K.; Ferguson, D.; Katz, R. F.; Li, Y.; Middleton, J. L.

    2015-12-01

    Changes in sea level influence the pressure of the solid Earth over entire ocean basins. While the absolute changes in sea level caused by glacial cycles are small relative to ocean depths, the temporal variations in sea level can lead to pressure changes of similar order to mantle upwelling rates, with the potential to significantly perturb short term rates of melt production at ocean ridges (Huybers and Langmuir, EPSL, 2009). Such changes could then lead to fluctuations in crustal thickness, magma composition and hydrothermal activity. To investigate possible relationships between glacial cycles and ocean ridge processes, we carried out an 18 day cruise of mapping and sediment coring to the Cleft Segment of the Juan de Fuca ridge. High resolution bathymetry was obtained on the west side of the ridge axis to beyond 1Ma to test whether abyssal hill fabric shows periodicities consistent with glacial cycles. Nine successful piston cores up to 7.6m in length provide a sedimentary record back to more than 600kyr to test for spatial and temporal variations in hydrothermal activity. Oxygen isotope stratigraphy on these cores is systematic and provides good age constraints. Short cores near the ridge axis provide a record of the current trace of hydrothermal activity in youngest sediments. Several of the cores impacted basement and recovered a basement sample. Above basement, basaltic glass shards were recovered in the bottom meter of sediment, raising the possibility of temporal records of basalt chemical compositions using the age constraints the sediments provide. The glass samples provide a unique and new perspective on ridge volcanism, since previous off-axis samples were restricted to dredging old fault scarps. Cores can be taken anywhere, raising the potential for global time series studies of ridge volcanism. The coupled bathymetry, sediment geochemistry and magmatic glass compositions hold the promise of a definitive advance in our understanding of the

  18. Seismic structure and seismicity at the southern Mariana Trough with hydrothermal activities

    NASA Astrophysics Data System (ADS)

    Sato, T.; Mizuno, M.; Takada, H.; Yamada, T.; Isse, T.; Shinohara, M.

    2012-12-01

    The Southern Mariana Trough back-arc spreading system shows asymmetry spreading, and has high relief at spreading axes, which infers abundant melt supply. Furthermore, five hydrothermal vents that extrude different water contents, exist within 5 km near the spreading axis. To investigate upper mantle structure, crustal structure and hypocenter distribution provide important constraint on following four main points to understand the back-arc spreading system; 1) imaging melt delivery to the spreading axis and off axis seamount including volcanic arc, 2) production and character of the crust, 3) relationship between melt supply and crustal formation, and 4) pathway and heat source for hydrothermal circulation with related to its formation. We conducted a seismic reflection/refraction survey and seismicity observation at the hydrothermal area in the Southern Mariana Trough from August to November in 2010. We used 9 ocean bottom seismometers, an air gun (GI gun) and a single channel streamer cable. We took 7 parallel lines and 7 perpendicular lines to the spreading center. Line length was 15 km each, and line interval was 2.5 km. From the survey and observation, we obtained very low seismicity at the hydrothermal area in the 3 month's observation. The reflection survey shows that some reflectors exist under the hydrothermal area. In this presentation, we will also show seismic velocity structures from the refraction survey.

  19. Enceladus and Europa: How Does Hydrothermal Activity Begin at the Surface?

    NASA Technical Reports Server (NTRS)

    Matson, D. L.; Castillo-Rogez, J. C.; Johnson, T. V.; Lunine, J. I.; Davies, A. G.

    2011-01-01

    The question of how the surface hydrothermal activity (e.g., eruptive plumes and heat flow) is initiated can be addressed within the frame-work of our "Perrier Ocean" model. This model delivers the necessary heat and chemicals to support the heat flow and plumes observed by Cassini in Enceladus' South Polar Region. The model employs closed-loop circulation of water from a sub-surface ocean. The ocean is the main reservoir of heat and chemicals, including dissolved gases. As ocean water moves up toward the surface, pressure is re-duced and gases exsolve forming bubbles. This bub-bly mixture is less dense than the icy crust and the buoyant ocean-water mixture rises toward the surface. Near the surface, heat and chemicals, including some volatiles, are delivered to the chambers in which plumes form and also to shallow reservoirs that keep the surface ice "warm". (Plume operations, per se, are as described by Schmidt et al. and Postberg et al. and are adopted by us.) After transferring heat, the water cools, bubbles contract and dissolve, and the mixture is now relatively dense. It descends through cracks in the crust and returns to the ocean. Once the closed-loop circulation has started it is self-sustaining. Loss of water via the erupting plumes is relatively negligible compared to the amount needed to maintain the heat flow.We note that the activity described herein for the the "Perrier-Ocean" model could, a priori, apply to all small icy bodies that sheltered an interior ocean at some point in their history.

  20. Linking microbial ultrastructure and physiology to iron depositional processes in deep sea hydrothermal environments

    NASA Astrophysics Data System (ADS)

    Chan, C. S.; Fleming, E. J.; Emerson, D.; Edwards, K. J.

    2008-12-01

    Clara S. Chan, Emily Fleming, David Emerson, Katrina J. Edwards Iron microbial mats have been discovered in a variety of deep-sea hydrothermal environments and are increasingly being recognized as more seafloor is explored. The predominant structures found in many of these mats are iron oxyhydroxide-rich filaments. One of the most common structures is a helical stalk bearing a resemblance to the twisted stalk of the terrestrial iron-oxidizing microbe, Gallionella ferruginea. While Gallionella has not been detected in, or isolated from, these mats microaerophilic iron-oxidizing, a stalk- forming bacterium, Mariprofundus ferrooxydans (PV-1 and related strains) has been isolated from mats at the Loihi seamount in Hawaii (Emerson et al. 2007, PLoS One 2(8): e667). Fossilized aggregates of iron filaments have been observed in the rock record (e.g. Little et al. 2004, Geomicrobiol. J. 21:415), and may represent ancient versions of these microbial mats. If this is shown to be true, such filaments would represent one of the few microfossil morphologies that can be linked to a specific microbial metabolism. We have used a combination of test tube culturing, microslide culturing, time lapse microscopy, and electron microscopy to study Mariprofundus stalk morphology and genesis and link these details to physiological responses to environmental chemistry. The goals include determining specific attributes of stalk morphology that can be used to determine the biogenicity of putative iron microfossils, and interpret the conditions of the depositional environment. Light microscopic observation of microslide cultures over the course of several days allowed for determination of bacterial response to developing oxygen and Fe(II) gradients. Once gradients have been established, given an abundant supply of oxygen, cells congregate in a band perpendicular to the gradient and stalks are formed, growing in the direction of increasing oxygen (and decreasing Fe) concentration. This

  1. Photocatalytic activity of tungsten-doped TiO2 with hydrothermal treatment under blue light irradiation.

    PubMed

    Putta, Thapanan; Lu, Ming-Chun; Anotai, Jin

    2011-09-01

    Tungsten doping and hydrothermal treatment were found to significantly improve the visible-light photoactivity of TiO(2) synthesized by the sol-gel method. It was observed that TiO(2) doped with a 0.5% W:Ti mole ratio and treated with 4 h of hydrothermal curing showed photoactivity under blue light irradiation equal to 74% of the commercial Degussa P-25 under UV irradiation, i.e., 0.01 mM 2-chlorophenol was completely removed in 120 and 90 min, respectively. Light absorptivity and photocatalytic activity under blue light irradiation were not dependent on the crystallite structure of the TiO(2). The oxidation kinetics under blue light irradiation can be effectively explained by the Langmuir-Hinshelwood model with an apparent reaction rate constant and a Langmuir constant of 3.60 × 10(-4) mM min(-1) and 206.53 mM(-1), respectively.

  2. Hydrothermal processing and enzymatic hydrolysis of sorghum bagasse for fermentable carbohydrates production.

    PubMed

    Dogaris, Ioannis; Karapati, Sofia; Mamma, Diomi; Kalogeris, Emmanuel; Kekos, Dimitris

    2009-12-01

    Untreated and hydrothermally treated sorghum bagasse (SB) was hydrolyzed to simple sugars by the synergistic action of cellulases and hemicellulases produced by the fungi Fusarium oxysporum and Neurospora crassa. Synergism between the two lignocellulolytic systems was maximized with the application of higher fraction of N. crassa enzymes. Hydrothermolysis of SB was studied at a wide range of treatment times and temperatures. At intense pretreatment conditions (210 degrees C for 20 min; logR(0)=4.54), the residual hemicellulose percentage was 17.45%, while formation of inhibitory products, 5-hydromethyl-furfural (HMF), furfural, acetic and formic acid, (0.21, 0.51, 3.36 and 1.80 g/l, respectively) remained in acceptable levels. Maximum conversion of cellulose and total polysaccharides of the untreated SB were 23.18% and 18.79%, respectively. Combining hydrothermal treatment and enzymatic hydrolysis of released oligosaccharides and insoluble solids resulted in improvement of cellulose (approximately 15% increase) and total polysaccharides (two fold) hydrolysis compared to that of untreated SB.

  3. Recent uplift and hydrothermal activity at Tangkuban Parahu volcano, west Java, Indonesia

    USGS Publications Warehouse

    Dvorak, J.; Matahelumual, J.; Okamura, A.T.; Said, H.; Casadevall, T.J.; Mulyadi, D.

    1990-01-01

    Tangkuban Parahu is an active stratovolcano located 17 km north of the city of Bandung in the province west Java, Indonesia. All historical eruptive activity at this volcano has been confined to a complex of explosive summit craters. About a dozen eruptions-mostly phreatic events- and 15 other periods of unrest, indicated by earthquakes or increased thermal activity, have been noted since 1829. The last magmatic eruption occurred in 1910. In late 1983, several small phreatic explosions originated from one of the summit craters. More recently, increased hydrothermal and earthquake activity occurred from late 1985 through 1986. Tilt measurements, using a spirit-level technique, have been made every few months since February 1981 in the summit region and along the south and east flanks of the volcano. Measurements made in the summit region indicated uplift since the start of these measurements through at least 1986. From 1981 to 1983, the average tilt rate at the edges of the summit craters was 40-50 microradians per year. After the 1983 phreatic activity, the tilt rate decreased by about a factor of five. Trilateration surveys across the summit craters and on the east flank of the volcano were conducted in 1983 and 1986. Most line length changes measured during this three-year period did not exceed the expected uncertainty of the technique (4 ppm). The lack of measurable horizontal strain across the summit craters seems to contradict the several years of tilt measurements. Using a point source of dilation in an elastic half-space to model tilt measurements, the pressure center at Tangkuban Parahu is located about 1.5 km beneath the southern part of the summit craters. This is beneath the epicentral area of an earthquake swarm that occurred in late 1983. The average rate in the volume of uplift from 1981 to 1983 was 3 million m3 per year; from 1983 to 1986 it averaged about 0.4 million m3 per year. Possible causes for this uplift are increased pressure within a very

  4. Making a black shale shine: the interaction of hydrothermal fluids and diagenetic processes

    NASA Astrophysics Data System (ADS)

    Gleeson, Sarah; Magnall, Joe; Reynolds, Merilie

    2016-04-01

    Hydrothermal fluids are important agents of mass and thermal transfer in the upper crust. This is exemplified by shale-hosted massive sulphide deposits (SHMS), which are anomalous accumulations of Zn and Pb sulphides (± barite) in sedimentary basins created by hydrothermal fluids. These deposits occur in passive margin settings and, typically, there is no direct evidence of magmatic input. Recent studies of Paleozoic deposits in the North American Cordillera (MacMillan Pass and Red Dog Districts) have shown that the deposits are formed in a sub-seafloor setting, where the potential for thermal and chemical gradients is high. Mineralization is characterized by the replacement and displacement of unconsolidated, partially lithified and lithified biosiliceous mudstones (± carbonates), and commonly the sulphide mineralization post-dates, and replaces, bedded barite units in the sediments. The Red Dog District (Alaska, USA) contain some of the largest Zn-Pb deposits ever discovered. The host-rocks are dominantly carbonaceous mudstones, with carbonate units and some radiolarites. The ore forms massive sulphide bodies that replace pyritized mudstones, barite and carbonate units. Lithological and textural relationships provide evidence that much of the ore formed in bioturbated, biosiliceous zones that may have had high primary porosity and/or permeability. Sediment permeability may have been further modified by aging of the silica rich sediments and the dissolution/replacement of carbonate and barite beds. At the Tom and Jason deposits (MacMillan Pass, Yukon) the fault-controlled hydrothermal upflow zone is uniquely preserved as an unequivocal vent complex. Here, the metal bearing fluids are hot (300°C), low salinity (6 wt% NaCl equiv.) and acidic (pH < 4.5). These fluids were initially in thermal and chemical disequilibrium with a partially lithified organic rich host-rock but cooled rapidly during fluid rock interaction and the input of diagenetic pore fluids

  5. Investigating microbial colonization in actively forming hydrothermal deposits using thermocouple arrays

    NASA Astrophysics Data System (ADS)

    Tivey, M. K.; Reysenbach, A. L.; Hirsch, M.; Steinberg, J.; Flores, G. E.

    2010-12-01

    Investigations of microbial colonization of very young hydrothermal deposits were carried out in 2009 at hydrothermal vents in the Lau Basin (SW Pacific), and in Guaymas Basin, Gulf of California, with a test deployment at the Rainbow vent field on the Mid-Atlantic Ridge in 2008. Our method entailed razing active chimneys and placing arrays of temperature probes (8 titanium-encased probes with their tips placed within a titanium cage) over the active flow. The chimneys that grew back through each array, encasing the temperature probe tips, were recovered after 2 to 15 days, along with temperature records. Molecular phylogenetic methods are being used to reveal the members of the microbial communities that developed in each chimney of known age and thermal history. A total of 15 array deployments were made at 10 vents in 6 different vent fields. Similar morphology beehives (with porous fine-grained interiors and steep temperature gradients across the outermost more-consolidated “wall”) formed at 2 of the 3 vents in Guaymas Basin (in 2 and 5 days at one vent and 3 and 15 days at a second), and at one vent each in the Kilo Moana (in 3 days), Tahi Moana (in 2.5 days), and Tui Malila (in 3 and 8 days) vent fields in the Lau Basin. In contrast, open conduit, thin walled chimneys grew within arrays at the Mariner vent field, Lau Basin, at 3 different vents (in 3 days at one vent, in 3 and 11 days at a second vent, and in 13 days at a third vent). A lower temperature (<280C) diffuser/spire with a filamentous biofilm formed in 15 days in an array at a hydrocarbon-rich vent in the Guaymas Basin. A similar biofilm formed after 6 days within an array placed earlier at this same vent, with little mineralization. Preliminary diversity data from the 6 and 15 day Guaymas deployments show an increased diversity of bacteria with time with initial colonizers being primarily sulfur-oxidizing Epsilonproteobacteria, with members of the Aquificales and Deltaproteobacteria appearing

  6. High-resolution surveys along the hot spot-affected Gálapagos Spreading Center: 3. Black smoker discoveries and the implications for geological controls on hydrothermal activity

    NASA Astrophysics Data System (ADS)

    Haymon, Rachel M.; White, Scott M.; Baker, Edward T.; Anderson, Peter G.; MacDonald, Ken C.; Resing, Joseph A.

    2008-12-01

    To explore effects of hot spots on mid-ocean ridge hydrothermal systems, we conducted nested sonar, hydrothermal plume, and near-bottom photographic surveys along the portion of the Galápagos Spreading Center (GSC) influenced by the Galápagos hot spot, from longitude 95°-89.5°W. We report the first active high-temperature black smokers to be found on the GSC, at longitudes 94°4.5'W and 91°56.2'-54.3'W; describe two areas of recently inactive smokers, at longitudes 91°23.4'-23.7'W and 91°13.8'W; and document an older inactive site, at longitude 90°33.4'W. All imaged vents issue either from dike-induced fissures along linear axial volcanic ridges and collapses or from a caldera. Magmatic control of hydrothermal systems also is revealed by spatial clustering of plumes within the topographically elevated middles of volcanic ridge segments with inferred centralized melt supply. In searched areas, smokers are more typical than diffuse flow vents, but total GSC plume incidence is half of that expected from the spreading rate. Why? Dike-fed fissures provide permeable pathways for efficient hydrothermal extraction of magmatic heat, but cones without calderas do not. Among many point-source cones surveyed, only the two with calderas had detectable plumes. Possibly, dominance of point-source over linear-source melt delivery on the GSC decreases plume incidence. Also, similar maturities of observed vents and their host lava flows indicate that hydrothermally active volcanic segments along the western GSC are contemporaneously in a waning phase of volcanic-hydrothermal activity. Perhaps ridge/hot spot interaction produces melt pulses that drive near-synchronous volcanic-hydrothermal activity on the volcanic segments spanning the hot spot. During active periods, hydrothermally active dike-fed fissures and calderas may be more abundant than we currently observe.

  7. Acid-base behavior in hydrothermal processing of wastes. 1998 annual progress report

    SciTech Connect

    Johnson, K.P.; Rossky, P.J.

    1998-06-01

    'A new technology, hydrothermal oxidation (also called supercritical water oxidation), is being developed to treat high level nuclear wastes. Nitrates are reduced to nitrogen; furthermore, phosphates, alumina sludge, and chromium are solubilized, and the sludge is reconstituted as fine oxide particles. A major obstacle to development of this technology has been a lack of scientific knowledge of chemistry in hydrothermal solution above 350 C, particularly acid-base behavior, and transport phenomena, which is needed to understand corrosion, metal-ion complexation, and salt precipitation and recovery. The objective is to provide this knowledge with in-situ UV-vis spectroscopic measurements and fully molecular computer simulation. A major objective of the experimental studies has been to determine the equilibria for Cr(VI) up to 420 C as this is a key species to be removed from nuclear wastes. A wide range of concentrations of KOH and perchloric acid were utilized to manipulate the acid-base equilibria and to understand the effects of ion solvation and ion pairing. The second system is the equilibria between nitric acid, nitrous acid, nitrogen dioxide, nitrite and nitrate ions and oxygen. For both of these systems, chemical equilibria has not been measured previously in hydrothermal solution at these temperatures. On the theoretical side, the authors have focused on the study of the transport properties of aqueous ions in supercritical water. The motivation for these studies is two fold. First, although transport coefficients are fundamental to solution chemistry reaction rates, the behavior of such transport properties over wide ranges of density and temperature are not well established experimentally, particularly at the densities typically of interest (< 0.5 g/cc). Second, due to practical challenges, ionic association equilibria in SCW is typically accessed via measurements of conductivity followed by analysis through a theoretical model that incorporates ion

  8. Tectonic and magmatic control of hydrothermal activity along the slow-spreading Central Indian Ridge, 8°S-17°S

    NASA Astrophysics Data System (ADS)

    Son, Juwon; Pak, Sang-Joon; Kim, Jonguk; Baker, Edward T.; You, Ok-Rye; Son, Seung-Kyu; Moon, Jai-Woon

    2014-05-01

    complex geology and expansive axial valleys typical of slow-spreading ridges makes evaluating their hydrothermal activity a challenge. This challenge has gone largely unmet, as the most undersampled MOR type for hydrothermal activity is slow spreading (20-55 mm/yr). Here we report the first systematic hydrothermal plume survey conducted on the Central Indian Ridge (CIR, 8°S-17°S), the most extensive such survey yet conducted on a slow-spreading ridge. Using a combined CTD/Miniature Autonomous Plume Recorder (MAPR) package, we used 118 vertical casts along seven segments of the CIR (˜700 km of ridge length) to estimate the frequency of hydrothermal activity. Evidence for hydrothermal activity (particle and methane plumes) was found on each of the seven spreading segments, with most plumes found between 3000 and 3500 m, generally <1000 m above bottom. We most commonly found plumes on asymmetric ridge sections where ultramafic massifs formed along one ridge flank near ridge-transform intersections or nontransform offsets. The estimated plume incidence (ph) for axial and wall casts (ph=0.30, 35 of 118 casts) is consistent with the existing global trend, indicating that the long-term magmatic budget on the CIR is the primary control on the spatial frequency of hydrothermal venting. Our results show that the tectonic fabric of the CIR strongly determines where hydrothermal venting is expressed, and that using only near-axial sampling might underestimate hydrothermal activity along slow-spreading and ultraslow-spreading ridges. Serpentinization is a minor contributor to the plume inventory, based on 15 profiles with methane anomalies only, predominantly at depths above the local valley walls.

  9. [Novel process utilizing alkalis assisted hydrothermal process to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water].

    PubMed

    Wang, Lei; Jin, Jian; Li, Xiao-dong; Chi, Yong; Yan, Jian-hua

    2010-08-01

    An alkalis assisted hydrothermal process was induced to stabilize heavy metals both from municipal solid waste or medical waste incinerator fly ash and waste water. The results showed that alkalis assisted hydrothermal process removed the heavy metals effectively from the waste water, and reduced leachability of fly ash after process. The heavy metal leachabilities of fly ash studied in this paper were Mn 17,300 microg/L,Ni 1650 microg/L, Cu 2560 microg/L, Zn 189,000 microg/L, Cd 1970 microg/L, Pb 1560 microg/L for medical waste incinerator fly ash; Mn 17.2 microg/L, Ni 8.32 microg/L, Cu 235.2 microg/L, Zn 668.3 microg/L, Cd 2.81 microg/L, Pb 7200 microg/L for municipal solid waste incinerator fly ash. After hydrothermal process with experimental condition [Na2CO3 dosage (5 g Na2CO3/50 g fly ash), reaction time = 10 h, L/S ratio = 10/1], the heavy metal removal efficiencies of medical waste incinerator fly ash were 86.2%-97.3%, and 94.7%-99.6% for municipal solid waste incinerator fly ash. The leachabilities of both two kinds of fly ash were lower than that of the Chinese national limit. The mechanism of heavy metal stabilization can be concluded to the chemisorption and physically encapsulation effects of aluminosilicates during its formation, crystallization and aging process, the high pH value has some contribution to the heavy metal removal and stabilization.

  10. Geologic history of Martian regolith breccia Northwest Africa 7034: Evidence for hydrothermal activity and lithologic diversity in the Martian crust

    USGS Publications Warehouse

    McCubbin, Francis M.; Boyce, Jeremy W.; Novak-Szabo, Timea; Santos, Alison; Tartese, Romain; Muttik, Nele; Domokos, Gabor; Vazquez, Jorge A.; Keller, Lindsay P.; Moser, Desmond E.; Jerolmack, Douglas J.; Shearer, Charles K.; Steele, Andrew; Elardo, Stephen M.; Rahman, Zia; Anand, Mahesh; Delhaye, Thomas; Agee, Carl B.

    2016-01-01

    The timing and mode of deposition for Martian regolith breccia Northwest Africa (NWA) 7034 were determined by combining petrography, shape analysis, and thermochronology. NWA 7034 is composed of igneous, impact, and brecciated clasts within a thermally annealed submicron matrix of pulverized crustal rocks and devitrified impact/volcanic glass. The brecciated clasts are likely lithified portions of Martian regolith with some evidence of past hydrothermal activity. Represented lithologies are primarily ancient crustal materials with crystallization ages as old as 4.4 Ga. One ancient zircon was hosted by an alkali-rich basalt clast, confirming that alkalic volcanism occurred on Mars very early. NWA 7034 is composed of fragmented particles that do not exhibit evidence of having undergone bed load transport by wind or water. The clast size distribution is similar to terrestrial pyroclastic deposits. We infer that the clasts were deposited by atmospheric rainout subsequent to a pyroclastic eruption(s) and/or impact event(s), although the ancient ages of igneous components favor mobilization by impact(s). Despite ancient components, the breccia has undergone a single pervasive thermal event at 500–800°C, evident by groundmass texture and concordance of ~1.5 Ga dates for bulk rock K-Ar, U-Pb in apatite, and U-Pb in metamict zircons. The 1.5 Ga age is likely a thermal event that coincides with rainout/breccia lithification. We infer that the episodic process of regolith lithification dominated sedimentary processes during the Amazonian Epoch. The absence of pre-Amazonian high-temperature metamorphic events recorded in ancient zircons indicates source domains of static southern highland crust punctuated by episodic impact modification.

  11. Geologic history of Martian regolith breccia Northwest Africa 7034: Evidence for hydrothermal activity and lithologic diversity in the Martian crust

    NASA Astrophysics Data System (ADS)

    McCubbin, Francis M.; Boyce, Jeremy W.; Novák-Szabó, Tímea; Santos, Alison R.; Tartèse, Romain; Muttik, Nele; Domokos, Gabor; Vazquez, Jorge; Keller, Lindsay P.; Moser, Desmond E.; Jerolmack, Douglas J.; Shearer, Charles K.; Steele, Andrew; Elardo, Stephen M.; Rahman, Zia; Anand, Mahesh; Delhaye, Thomas; Agee, Carl B.

    2016-10-01

    The timing and mode of deposition for Martian regolith breccia Northwest Africa (NWA) 7034 were determined by combining petrography, shape analysis, and thermochronology. NWA 7034 is composed of igneous, impact, and brecciated clasts within a thermally annealed submicron matrix of pulverized crustal rocks and devitrified impact/volcanic glass. The brecciated clasts are likely lithified portions of Martian regolith with some evidence of past hydrothermal activity. Represented lithologies are primarily ancient crustal materials with crystallization ages as old as 4.4 Ga. One ancient zircon was hosted by an alkali-rich basalt clast, confirming that alkalic volcanism occurred on Mars very early. NWA 7034 is composed of fragmented particles that do not exhibit evidence of having undergone bed load transport by wind or water. The clast size distribution is similar to terrestrial pyroclastic deposits. We infer that the clasts were deposited by atmospheric rainout subsequent to a pyroclastic eruption(s) and/or impact event(s), although the ancient ages of igneous components favor mobilization by impact(s). Despite ancient components, the breccia has undergone a single pervasive thermal event at 500-800°C, evident by groundmass texture and concordance of 1.5 Ga dates for bulk rock K-Ar, U-Pb in apatite, and U-Pb in metamict zircons. The 1.5 Ga age is likely a thermal event that coincides with rainout/breccia lithification. We infer that the episodic process of regolith lithification dominated sedimentary processes during the Amazonian Epoch. The absence of pre-Amazonian high-temperature metamorphic events recorded in ancient zircons indicates source domains of static southern highland crust punctuated by episodic impact modification.

  12. Chlorine isotope and Cl-Br fractionation in fluids of Poás volcano (Costa Rica): Insight into an active volcanic-hydrothermal system

    NASA Astrophysics Data System (ADS)

    Rodríguez, Alejandro; Eggenkamp, H. G. M.; Martínez-Cruz, María; van Bergen, Manfred J.

    2016-10-01

    Halogen-rich volcanic fluids issued at the surface carry information on properties and processes operating in shallow hydrothermal systems. This paper reports a long-term record of Cl-Br concentrations and δ37Cl signatures of lake water and fumaroles from the active crater of Poás volcano (Costa Rica), where surface expressions of magmatic-hydrothermal activity have shown substantial periodic changes over the last decades. Both the hyperacid water of its crater lake (Laguna Caliente) and subaerial fumaroles show significant temporal variability in Cl-Br concentrations, Br/Cl ratios and δ37Cl, reflecting variations in the mode and magnitude of volatile transfer. The δ37Cl signatures of the lake, covering the period 1985-2012, show fluctuations between + 0.02 ± 0.06‰ and + 1.15 ± 0.09‰. Condensate samples from adjacent fumaroles on the southern shore, collected during the interval (2010-2012) with strong changes in gas temperature (107-763°C), display a much larger range from - 0.43 ± 0.09‰ to + 14.09 ± 0.08‰. Most of the variations in Cl isotope, Br/Cl and concentration signals can be attributed to interaction between magma-derived gas and liquid water in the volcanic-hydrothermal system below the crater. The δ37Cl were lowest and closest to magmatic values in (1) fumarolic gas that experienced little or no interaction with subsurface water and followed a relatively dry pathway, and (2) water that captured the bulk of magmatic halogen output so that no phase separation could induce fractionation. In contrast, elevated δ37Cl can be explained by partial scavenging and fractionation during subsurface gas-liquid interaction. Hence, strong Cl isotope fractionation leading to very high δ37Cl in Poás' fumaroles indicates that they followed a wet pathway. Highest δ37Cl values in the lake water were found mostly in periods when it received a significant input from subaqueous fumaroles or when high temperatures and low pH caused HCl evaporation. It is

  13. Synthesis of highly magnetic graphite-encapsulated FeCo nanoparticles using a hydrothermal process.

    PubMed

    Lee, Seung Jae; Cho, Jee-Hyun; Lee, Chulhyun; Cho, Janggeun; Kim, Yong-Rok; Park, Joung Kyu

    2011-09-16

    The graphite encapsulation of metal alloy magnetic nanoparticles has attracted attention for biological applications because of the high magnetization of the encapsulated particles. However, most of the synthetic methods have limitations in terms of scalability and economics because of the demanding synthetic conditions and low yields. Here, we show that well controlled graphite-encapsulated FeCo core-shell nanoparticles can be synthesized by a hydrothermal method, simply by mixing Fe/Co with sucrose as a carbon source. Various Fe/Co metal ratios were used to determine the compositional dependence of the saturation magnetization and relaxivity coefficient. Transmission electron microscopy indicated that the particle sizes were 7 nm. In order to test the capability of graphite-encapsulated FeCo nanoparticles as magnetic resonance imaging (MRI) contrast agents, these nanoparticles were solubilized in water by the nonspecific physical adsorption of sodium dodecylbenzene sulfonate.

  14. Characterization of products from hydrothermal carbonization of orange pomace including anaerobic digestibility of process liquor.

    PubMed

    Erdogan, Ezgi; Atila, Buse; Mumme, Jan; Reza, M Toufiq; Toptas, Asli; Elibol, Murat; Yanik, Jale

    2015-11-01

    In this study, the effect of the temperature and reaction time on hydrothermal carbonization (HTC) of orange pomace was investigated. In addition, a set of anaerobic batch tests were performed to determine the resulting biogas and methane potential of the spent liquor. Hydrochar yields followed a decreasing trend with the increasing temperature, whereas reaction time had no considerably effect on the yield. The evolution of the H/C and O/C atomic ratios from the raw material to the hydrochars suggested that dehydration reactions prevail during HTC. The hydrochars tended to become enriched in Ca, Mg and P minerals by increasing HTC temperature. The heavy metal contents in hydrochars were found below limits and no PAH compound was detected. Anaerobic digestion tests showed that the aqueous phase from HTC can be used as feedstocks for biogas production.

  15. Algal biofuels from urban wastewaters: maximizing biomass yield using nutrients recycled from hydrothermal processing of biomass.

    PubMed

    Selvaratnam, T; Pegallapati, A K; Reddy, H; Kanapathipillai, N; Nirmalakhandan, N; Deng, S; Lammers, P J

    2015-04-01

    Recent studies have proposed algal cultivation in urban wastewaters for the dual purpose of waste treatment and bioenergy production from the resulting biomass. This study proposes an enhancement to this approach that integrates cultivation of an acidophilic strain, Galdieria sulphuraria 5587.1, in a closed photobioreactor (PBR); hydrothermal liquefaction (HTL) of the wet algal biomass; and recirculation of the nutrient-rich aqueous product (AP) of HTL to the PBR to achieve higher biomass productivity than that could be achieved with raw wastewater. The premise is that recycling nutrients in the AP can maintain optimal C, N and P levels in the PBR to maximize biomass growth to increase energy returns. Growth studies on the test species validated growth on AP derived from HTL at temperatures from 180 to 300°C. Doubling N and P concentrations over normal levels in wastewater resulted in biomass productivity gains of 20-25% while N and P removal rates also doubled.

  16. The effect of solution chemistry on the preparation of MgAl{sub 2}O{sub 4} by hydrothermal-assisted sol-gel processing

    SciTech Connect

    Amini, M.M. . E-mail: m-pouramini@cc.sbu.ac.ir; Mirzaee, M.; Sepanj, N.

    2007-03-22

    Preparation of magnesium aluminate spinel powder by hydrothermal-assisted sol-gel processing from MgAl{sub 2}(OCH{sub 2}CH{sub 2}OR){sub 8}, R=CH{sub 3} (1), CH{sub 2}CH{sub 2}OCH{sub 3} (2), MgAl{sub 2}[OCH(CH{sub 3}){sub 2}]{sub 8} (3) and MgAl{sub 2}(O- {sup s}Bu){sub 8} (4) in toluene and parent alcohol has been investigated. Coordination status of aluminum atom in precursors was determined by {sup 27}Al NMR and correlation between coordination number of aluminum and development of spinel phase in hydrothermal-assisted sol-gel processing has been studied. The gels obtained from hydrothermal-assisted hydrolysis of magnesium-aluminum alkoxides that contain six-coordinated aluminum atoms in solution (1 and 2) after calcination at 700 deg. C resulted in the formation of pure spinel phase, whereas in similar hydrolysis and calcination processes of precursors that contain four-coordinated aluminum (3 and 4) spinel phase forms along with some Al{sub 2}O{sub 3} and MgO. Selected powders obtained from hydrothermal-assisted sol-gel processing were characterized by thermal analysis (TGA/DSC), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Results indicate that the coordination status of aluminum in the precursor is very crucial for the formation of pure phase spinel. The morphology of prepared spinels was studied by SEM and the results showed that the solvent in hydrothermal-assisted sol-gel processing has a marked effect on the morphology of the resulting MgAl{sub 2}O{sub 4}. In hydrothermal-assisted sol-gel processing of aluminum-magnesium alkoxides in hydrophobic solvent, spherical particles are formed, while in the parent alcohol, non-spherical powders are formed.

  17. Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity

    PubMed Central

    Wu, Shuisheng; Dai, Weili

    2017-01-01

    SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs. PMID:28336888

  18. Microwave-Hydrothermal Synthesis of SnO2-CNTs Hybrid Nanocomposites with Visible Light Photocatalytic Activity.

    PubMed

    Wu, Shuisheng; Dai, Weili

    2017-03-03

    SnO2 nanoparticles coated on carbon nanotubes (CNTs) were prepared via a simple microwave-hydrothermal route. The as-obtained SnO2-CNTs composites were characterized using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2-CNTs for degradation of Rhodamine B under visible light irradiation was investigated. The results show that SnO2-CNTs nanocomposites have a higher photocatalytic activity than pure SnO2 due to the rapid transferring of electrons and the effective separation of holes and electrons on SnO2-CNTs.

  19. Crustal flushing and its relationship to magnetic and hydrothermal processes on the East Pacific Rise crest

    NASA Technical Reports Server (NTRS)

    Wright, Dawn J.; Haymon, Rachel M.; Fornari, Daniel J.

    1995-01-01

    The deep-towed Argo I optical/acoustical vehicle and a geographic information system (GIS) have been used to establish the abundance, widths, and spatial distribution of fissures, as well as the relative age distribution of lavas along the narrow (less than 500 m wide) axial zone of the East Pacific Rise (EPR) from 9 deg 12 min to 9 deg 54 min N. On a second-order scale (approximately 78 km long), wider but less numerous fissures are found in the northern portion of the survey area; this changes to narrower, more abundant fissures in the south. A profile of the cumulative width added by fissures to the axial zone exhibits minima in three areas along strike (near 9 deg 49 min, 9 deg 35 min, and 9 deg 15 min N), where the most recent eruptions have occurred above sites of magmatic injection from the upper mantle, filling and covering older fissures. On a fourth-order scale (5-15 km long) the mean density of fissuring on a given segment is greater where relative axial lava age is greater. Fissure density also correlates with hydrothermal vent abundance and type. Increased cracking toward segment tips is observed at the second-order scale, whereas fourth-order segments tend to be more cracked in the middle. Cracking on a fourth-order scale may be driven by the propagation of dikes, rather than by the far-field plate stresses. The above relations constrain the model of Haymon et al. (1991) in which individual fourth-order segments are in different phases of a volcanic-hydrothermal-tectonic cycle.

  20. Geochemical constraints on the diversity and activity of H2 -oxidizing microorganisms in diffuse hydrothermal fluids from a basalt- and an ultramafic-hosted vent.

    PubMed

    Perner, Mirjam; Petersen, Jillian M; Zielinski, Frank; Gennerich, Hans-Hermann; Seifert, Richard

    2010-10-01

    Mixing processes of reduced hydrothermal fluids with oxygenated seawater and fluid-rock reactions contribute to the chemical signatures of diffuse venting and likely determine the geochemical constraints on microbial life. We examined the influence of fluid chemistry on microbial diversity and activity by sampling diffuse fluids emanating through mussel beds at two contrasting hydrothermal vents. The H(2) concentration was very low at the basalt-hosted Clueless site, and mixing models suggest O(2) availability throughout much of the habitat. In contrast, effluents from the ultramafic-hosted Quest site were considerably enriched in H(2) , while O(2) is likely limited to the mussel layer. Only two different hydrogenase genes were identified in clone libraries from the H(2) -poor Clueless fluids, but these fluids exhibited the highest H(2) uptake rates in H(2) -spiked incubations (oxic conditions, at 18 °C). In contrast, a phylogenetically diverse H(2) -oxidizing potential was associated with distinct thermal conditions in the H(2) -rich Quest fluids, but under oxic conditions, H(2) uptake rates were extremely low. Significant stimulation of CO(2) fixation rates by H(2) addition was solely illustrated in Quest incubations (P-value <0.02), but only in conjunction with anoxic conditions (at 18 °C). We conclude that the factors contributing toward differences in the diversity and activity of H(2) oxidizers at these sites include H(2) and O(2) availability.

  1. The giant Carlin gold province: A protracted interplay of orogenic, basinal, and hydrothermal processes above a lithospheric boundary

    USGS Publications Warehouse

    Emsbo, P.; Groves, D.I.; Hofstra, A.H.; Bierlein, F.P.

    2006-01-01

    Northern Nevada hosts the only province that contains multiple world-class Carlin-type gold deposits. The first-order control on the uniqueness of this province is its anomalous far back-arc tectonic setting over the rifted North American paleocontinental margin that separates Precambrian from Phanerozoic subcontinental lithospheric mantle. Globally, most other significant gold provinces form in volcanic arcs and accreted terranes proximal to convergent margins. In northern Nevada, periodic reactivation of basement faults along this margin focused and amplified subsequent geological events. Early basement faults localized Devonian synsedimentary extension and normal faulting. These controlled the geometry of the Devonian sedimentary basin architecture and focused the discharge of basinal brines that deposited syngenetic gold along the basin margins. Inversion of these basins and faults during subsequent contraction produced the complex elongate structural culminations that characterize the anomalous mineral deposit "trends." Subsequently, these features localized repeated episodes of shallow magmatic and hydrothermal activity that also deposited some gold. During a pulse of Eocene extension, these faults focused advection of Carlin-type fluids, which had the opportunity to leach gold from gold-enriched sequences and deposit it in reactive miogeoclinal host rocks below the hydrologic seal at the Roberts Mountain thrust contact. Hence, the vast endowment of the Carlin province resulted from the conjunction of spatially superposed events localized by long-lived basement structures in a highly anomalous tectonic setting, rather than by the sole operation of special magmatic or fluid-related processes. An important indicator of the longevity of this basement control is the superposition of different gold deposit types (e.g., Sedex, porphyry, Carlin-type, epithermal, and hot spring deposits) that formed repeatedly between the Devonian and Miocene time along the trends

  2. Observations of Flatfish "Spas" From Three Hydrothermally Active Seamounts in the Mariana Arc

    NASA Astrophysics Data System (ADS)

    Dower, J.; Tunnicliffe, V.; Tyler, J.; Juniper, K.; Stevens, C.; Kouris, A.; Takano, B.

    2006-12-01

    During a cruise to the Mariana Islands in spring 2004, dense aggregations of small flatfish were recorded from areas of diffuse flow on two hydrothermally active seamounts known as Kasuga-2 and Daikoku. This is quite novel, as flatfish are not known to be part of vent faunas elsewhere. Based on a single specimen, it was determined to be a new species of tonguefish in the genus Symphurus, and is currently under description. In October 2005, we returned to the Mariana Arc and collected about 60 specimens from Kasuga-2, Daikoku, and a third site, Nikko Seamount. Interestingly, the Nikko specimens were about twice as large as the flatfish from Kasuga-2 and Daikoku. Current molecular work (using the Barcode of Life Data System) will determine the relationship among these populations, and verify whether they are the same species. Under the microscope, the sandy sediments from the flatfish habitat were found to be full of tiny nematodes and polychaete worms. Our current hypothesis is that the fish are feeding on both and, thus, are ultimately supported by chemosynthesis, since the worms likely feed on bacteria in the sediments. However, during our most recent cruise in May 2006, we also observed several instances in which dead (or nearly dead) mid-water fish and shrimp fell out of the water column onto the bottom, after which they were almost immediately fed upon by the flatfish. This suggests that there may also be an additional energy subsidy to the seamount benthos from the water column. We hypothesize that sulfite (or some other toxic chemical) in the plume overlying these active volcanoes either kills or anesthetizes small pelagics that get advected over the seamount summit while feeding in near-surface waters at night. Stable isotope and lipid analysis of samples from these "fish spas" are currently underway to establish trophic relationships. We hope to use otolith microstructure analyses to quantify individual growth trajectories and population age structure of

  3. Constraints on Alpine hydrothermal activity and deformation from U-Th-Pb dating of cleft monazite and xenotime (Western Alps)

    NASA Astrophysics Data System (ADS)

    Grand'Homme, Alexis; Janots, Emilie; Bosse, Valerie; Seydoux-Guillaume, Anne-Magali; De Ascencao, Roger

    2016-04-01

    In this large-scale regional study, age of hydrothermal monazite (and xenotime) precipitation has been investigated through in-situ U-Th-Pb dating of crystals collected in 11 clefts (veins) taken in the internal and external massifs (Western Alps). The investigated clefts are composed of quartz, chlorite (± epidote), albite and millimetric accessory minerals (monazite, apatite, xenotime, anatase, rutile). Prior to dating, cleft monazite composition was thoroughly studied to reveal potential zoning. In-situ dating through different compositional domains of single monazite crystal yields well-resolved Th-Pb ages (typically with 0.1-0.3 Ma resolution) indicating for growth episodes with short duration. Comparison of U-Pb and Th-Pb dating indicates that the U-Pb systematics appears successful to date cleft monazite with low Th/U ratio (typically <30). In one cleft, in which monazite and xenotime coexist, xenotime was dated using the monazite analytical protocol. Hydrothermal xenotime has remarkably high Th/U ratio and U-Pb dating shows evidence of 206Pb excess. In comparison, Th-Pb dating gives robust ages (35.2 ± 0.8 Ma) that are close but higher than the monazite date obtained in the same cleft (32.3 ± 0.3 Ma). Brief episodic monazite crystallization is likely attributed to enhanced hydrothermal activity during periods of higher tectonic activity. Correlation with other geochronological data suggests that it occurs in a host-rock that already cooled down at temperature close or below to the zircon fission track. In the Belledonne massif, the new monazite ages confirm for two periods of hydrothermal activity at around 11-13 Ma and 8-6 Ma, respectively. Only one vertical cleft monazite was investigated in the Mont-Blanc massif but it gives an age that is similar to the early population of the Belledonne massif (11.1 ± 0.2 Ma). Monazite dating therefore suggests for similar late-stage tectonic activity from Belledonne up to the Aar massifs, likely due to dextral

  4. Volcanic and Tectonic Setting of Hydrothermal Activity on the Southern Mid-Atlantic Ridge, 4° - 11°S

    NASA Astrophysics Data System (ADS)

    Melchert, B.; Devey, C. W.; German, C. R.; Haase, K. M.; Koschinsky, A.; Lackschewitz, K.; Yoerger, D. R.

    2006-12-01

    The recurrence rate of volcanism at mid-ocean ridges should drop with spreading rate. Although the southern Mid-Atlantic Ridge, with a spreading full rate of ~3.6 cm/yr, might therefore be expected to show only sporadic magmatic activity, we present information on recently-discovered volcanically, tectonically and hydrothermally active areas south of the equator (at 4°48'S and 9°33'S, see also German et al. 2005; Haase et al. 2005 EOS Trans. AGU 86 (52) Fall Meet. Suppl. Abstr. OS21C-04 & -05). Around the 4°48'S area the median valley floor forms a ~10 km wide, hour-glass shaped, plateau with water depths of around 3000 m. Four closely-spaced vent fields (the high-temperature sites Turtle Pits, Red Lion and Comfortless Cove and the diffuse low-temperature Wideawake site) occur along a flat (total relief 50 m), volcanically and tectonically active 2 km section of this plateau (see German et al. 2005, Haase et al. 2005 op. cit. also Koschinsky et al. this meeting). The Turtle Pits site lies within a small depression associated with a fracture marked by aligned collapse pits. This central depression is surrounded by laminated sheet flows to the north and northwest, whereas jumbled flows are more prevalent to the east. Comfortless Cove is also associated with young volcanics and shows strong tectonic influence on vent location. Red Lion in contrast shows no clear tectonic control - it is characterised by four active chimneys which sit directly on a pillow lava floor. The 9°33'S area is situated on 11 km-thick crust (Bruguier et al. 2003 JGR 108 2093) at 1490 m water depth and is marked by fresh pillow lavas, sheet flows, lava lakes and collapse structures. Low- temperature, diffuse hydrothermal activity is abundant in the area (Haase et al. 2005; Koschinsky et al. 2006 op. cit.) as are larger extinct hydrothermal mounds suggesting more vigourous hydrothermalism in the past. All sites are located east of a large NNW trending escarpment flanking horst and graben

  5. Screw-dislocation-driven growth of ZnO nanotubes seeded by self-perpetuating spirals during hydrothermal processing

    NASA Astrophysics Data System (ADS)

    Kim, Sojin; Kang, Hyon Chol

    2016-09-01

    We report the effects of precursor concentration on the characteristics of ZnO nanostructures during hydrothermal processing. Self-perpetuating surface spirals are fabricated at concentrations of 0.25 and 0.5 M, with samples grown at concentrations of 0.05 and 0.125 M exhibiting ZnO nanorods. This can be explained by a change in the growth mode from an initial columnar growth to a screw-dislocation-driven growth with decreased supersaturation. The screw dislocations nucleate at the V-shaped valleys of the columnar boundaries during the intermediate stage. We demonstrate that continuous screw-dislocation-driven growth leads to the formation of ZnO nanotubes having Burger's vectors of 1.45 nm.

  6. Stratigraphic development and hydrothermal activity in the central western Cascade Range, Oregon

    SciTech Connect

    Cummings, M.L.; Bull, M.K. ); Pollock, J.M. ); Thompson, G.D. )

    1990-11-10

    Two volcanic sequences bounded by erosional unconformities compose the stratigraphy of the North Santiam mining district, Western Cascade Range, Oregon. Diorite, grandodiorite, and leucocratic quartz porphyry dikes, stocks, and sills intrude the breccias, flows, and tuffs of a volcanic center in the older Sardine Formation. Tourmaline-bearing breccia pipes are associated with the porphyritic granodiorite intrusions. An erosional unconformity separates the Sardine Formation from the overlying Elk Lake formation. The alteration patterns in the two formations are consistent with the development of hydrothermal systems during the eruption of each formation. However, the development of the two hydrothermal systems is separated by a period of erosion of the older volcanic pile. Early formation of mineralization that resembles porphyry copper deposits occurred within the Sardine Formation, and later, after eruption of the Elk Lake formation, epithermal veins and alteration developed along faults, fractures, and the margins of dikes in the Sardine Formation.

  7. Synthesis and photocatalytic activity for water-splitting reaction of nanocrystalline mesoporous titania prepared by hydrothermal method

    SciTech Connect

    Jitputti, Jaturong; Pavasupree, Sorapong; Suzuki, Yoshikazu; Yoshikawa, Susumu

    2007-05-15

    Nanocrystalline mesoporous TiO{sub 2} was synthesized by hydrothermal method using titanium butoxide as starting material. XRD, SEM, and TEM analyses revealed that the synthesized TiO{sub 2} had anatase structure with crystalline size of about 8 nm. Moreover, the synthesized titania possessed a narrow pore size distribution with average pore diameter and high specific surface area of 215 m{sup 2}/g. The photocatalytic activity of synthesized TiO{sub 2} was evaluated with photocatalytic H{sub 2} production from water-splitting reaction. The photocatalytic activity of synthesized TiO{sub 2} treated with appropriate calcination temperature was considerably higher than that of commercial TiO{sub 2} (Ishihara ST-01). The utilization of mesoporous TiO{sub 2} photocatalyst with high crystallinity of anatase phase promoted great H{sub 2} production. Furthermore, the reaction temperature significantly influences the water-splitting reaction. - Graphical abstract: Nanocrystalline mesoporous TiO{sub 2} was synthesized by hydrothermal method. The physical properties of the synthesized TiO{sub 2} were thoroughly studied in relation to its photocatalytic activity for H{sub 2} evolution from water-splitting reaction. It was found that the photocatalytic activity of synthesized TiO{sub 2} treated with appropriate calcination temperature was considerably higher than that of commercial TiO{sub 2} (Ishihara ST-01)

  8. Coupled RNA-SIP and metatranscriptomics of active chemolithoautotrophic communities at a deep-sea hydrothermal vent

    PubMed Central

    Fortunato, Caroline S; Huber, Julie A

    2016-01-01

    The chemolithoautotrophic microbial community of the rocky subseafloor potentially provides a large amount of organic carbon to the deep ocean, yet our understanding of the activity and metabolic complexity of subseafloor organisms remains poorly described. A combination of metagenomic, metatranscriptomic, and RNA stable isotope probing (RNA-SIP) analyses were used to identify the metabolic potential, expression patterns, and active autotrophic bacteria and archaea and their pathways present in low-temperature hydrothermal fluids from Axial Seamount, an active submarine volcano. Metagenomic and metatranscriptomic results showed the presence of genes and transcripts for sulfur, hydrogen, and ammonium oxidation, oxygen respiration, denitrification, and methanogenesis, as well as multiple carbon fixation pathways. In RNA-SIP experiments across a range of temperatures under reducing conditions, the enriched 13C fractions showed differences in taxonomic and functional diversity. At 30 °C and 55 °C, Epsilonproteobacteria were dominant, oxidizing hydrogen and primarily reducing nitrate. Methanogenic archaea were also present at 55 °C, and were the only autotrophs present at 80 °C. Correspondingly, the predominant CO2 fixation pathways changed from the reductive tricarboxylic acid (rTCA) cycle to the reductive acetyl-CoA pathway with increasing temperature. By coupling RNA-SIP with meta-omics, this study demonstrates the presence and activity of distinct chemolithoautotrophic communities across a thermal gradient of a deep-sea hydrothermal vent. PMID:26872039

  9. Coupled RNA-SIP and metatranscriptomics of active chemolithoautotrophic communities at a deep-sea hydrothermal vent.

    PubMed

    Fortunato, Caroline S; Huber, Julie A

    2016-08-01

    The chemolithoautotrophic microbial community of the rocky subseafloor potentially provides a large amount of organic carbon to the deep ocean, yet our understanding of the activity and metabolic complexity of subseafloor organisms remains poorly described. A combination of metagenomic, metatranscriptomic, and RNA stable isotope probing (RNA-SIP) analyses were used to identify the metabolic potential, expression patterns, and active autotrophic bacteria and archaea and their pathways present in low-temperature hydrothermal fluids from Axial Seamount, an active submarine volcano. Metagenomic and metatranscriptomic results showed the presence of genes and transcripts for sulfur, hydrogen, and ammonium oxidation, oxygen respiration, denitrification, and methanogenesis, as well as multiple carbon fixation pathways. In RNA-SIP experiments across a range of temperatures under reducing conditions, the enriched (13)C fractions showed differences in taxonomic and functional diversity. At 30 °C and 55 °C, Epsilonproteobacteria were dominant, oxidizing hydrogen and primarily reducing nitrate. Methanogenic archaea were also present at 55 °C, and were the only autotrophs present at 80 °C. Correspondingly, the predominant CO2 fixation pathways changed from the reductive tricarboxylic acid (rTCA) cycle to the reductive acetyl-CoA pathway with increasing temperature. By coupling RNA-SIP with meta-omics, this study demonstrates the presence and activity of distinct chemolithoautotrophic communities across a thermal gradient of a deep-sea hydrothermal vent.

  10. Photocatalytic activity of BiFeO{sub 3} nanoparticles synthesized through hydrothermal method

    SciTech Connect

    Dhanalakshmi, Radhalayam; Muneeswaran, M.; Vanga, Pradeep Reddy; Ashok, M.; Giridharan, N. V.

    2015-06-24

    Multiferroic BiFeO{sub 3} (BFO) nanoparticles (Nps) were synthesized using hydrothermal method. From the X-Ray diffraction analysis (XRD), the synthesized Nps were found to having rhombohedral structure with R3c space group confirmed by Rietveld analysis. Fourier transform infrared spectroscopy (FTIR) analysis was carried out to identify the chemical bonds present in the BFO Nps. Photocatalytic properties of synthesized Nps were studied for the degradation of Methylene Blue (MB) dye under visible light of 150W.

  11. Carbon Isotopes of Alkanes in Hydrothermal Abiotic Organic Synthesis Processes at High Temperatures and Pressures: An Experimental Study

    NASA Technical Reports Server (NTRS)

    Fu, Qi; Socki, Richard A.; Niles, Paul B.

    2010-01-01

    Observation of methane in the Martian atmosphere has been reported by different detection techniques [1-4]. With more evidence showing extensive water-rock interaction in Martian history [5-7], abiotic formation by Fischer-Tropsch Type (FTT) synthesis during serpentization reactions may be one possible process responsible for methane generation on Mars [8, 9]. While the experimental studies performed to date leave little doubt that chemical reactions exist for the abiotic synthesis of organic compounds by mineral surface-catalyzed reactions [10-12], little is known about the reaction pathways by which CO2 and/or CO are reduced under hydrothermal conditions. Carbon and hydrogen isotope measurements of alkanes have been used as an effective tool to constrain the origin and reaction pathways of hydrocarbon formation. Alkanes generated by thermal breakdown of high molecular weight organic compounds have carbon and hydrogen isotopic signatures completely distinct from those formed abiotically [13-15]. Recent experimental studies, however, showed that different abiogenic hydrocarbon formation processes (e.g., polymerization vs. depolymerization) may have different carbon and hydrogen isotopic patterns [16]. Results from previous experiments studying decomposition of higher molecular weight organic compounds (lignite) also suggested that pressure could be a crucial factor affecting fractionation of carbon isotopes [17]. Under high pressure conditions, no experimental data are available describing fractionation of carbon isotope during mineral catalyzed FTT synthesis. Thus, hydrothermal experiments present an excellent opportunity to provide the requisite carbon isotope data. Such data can also be used to identify reaction pathways of abiotic organic synthesis under experimental conditions.

  12. Field Trip Guide to Serpentinite, Silica-Carbonate Alteration, and Related Hydrothermal Activity in the Clear Lake Region, California

    SciTech Connect

    Fraser Goff; George Guthrie

    1999-06-01

    This guide is designed to familiarize scientists with the geology, structure, alteration, and fluids typical of California serpentinites for purposes of carbon dioxide sequestration (Lackner et al., 1995). Goff et al. (1997) and Goff and Lackner (1998) describe the geology and geochemistry of some of the serpentinites from this area. Mechanisms of silica-carbonate alteration were outlined by Barnes et al. (1973). Donnelly-Nolan et al. (1993) most recently reviewed relations between regional hydrothermal alteration and Quarternary volcanic activity. Stanley et al. (1998) summarized geophysical characteristics of the region.

  13. Hydrothermal processes at Gusev Crater: An evaluation of Paso Robles class soils

    USGS Publications Warehouse

    Yen, A. S.; Morris, R.V.; Clark, B. C.; Gellert, Ralf; Knudson, A.T.; Squyres, S.; Mittlefehldt, D. W.; Ming, D. W.; Arvidson, R.; McCoy, T.; Schmidt, M.; Hurowitz, J.; Li, R.; Johnson, J. R.

    2008-01-01

    The Mars Exploration Rover Spirit analyzed multiple occurrences of sulfur-rich, light-toned soils along its traverse within Gusev Crater. These hydrated deposits are not readily apparent in images of undisturbed soil but are present at shallow depths and were exposed by the actions of the rover wheels. Referred to as 'Paso Robles' class soils, they are dominated by ferric iron sulfates, silica, and Mg-sulfates. Ca-sulfates, Ca-phosphates, and other minor phases are also indicated in certain specific samples. The chemical compositions are highly variable over both centimeter-scale distances and between the widely separated exposures, but they clearly reflect the elemental signatures of nearby rocks. The quantity of typical basaltic soil mixed into the light-toned materials prior to excavation by the rover wheels is minimal, suggesting negligible reworking of the deposits after their initial formation. The mineralogy, geochemistry, variability, association with local compositions, and geologic setting of the deposits suggest that Paso Robles class soils likely formed as hydrothermal and famarolic condensates derived from magma degassing and/ or oxidative alteration of crustal iron sulfide deposits. Their occurrence as unconsolidated, near-surface soils permits, though does not require, an age that is significantly younger than that of the surrounding rocks. Copyright 2008 by the American Geophysical Union.

  14. Growth and photocatalytic properties of Sb-doped ZnO nanoneedles by hydrothermal process

    NASA Astrophysics Data System (ADS)

    Abaker, M.; Umar, Ahmad; Al-Sayari, S. A.; Dar, G. N.; Faisal, M.; Kim, S. H.; Hwang, S. W.

    2011-10-01

    This paper reports a facile hydrothermal synthesis of Sb-doped ZnO nanoneedles by using aqueous mixtures of zinc chloride, antimony (Sb) chloride, hexamethylenetetramine (HMTA) and ammonium hydroxide at low temperature of 110 °C. The morphological characterizations of as-synthesized nanoneedles were done by field emission scanning electron microscopy (FESEM) which reveals that the nanoneedles are grown in large-quantity and arranged in such a special manner that they made flower-like morphologies. The structural characterization of as-synthesized nanoneedles was investigated by X-ray diffraction (XRD) pattern which confirm the well-crystalline and wurtzite hexagonal phase of as-synthesized products. The compositional characterization of as-synthesized nanoneedles was characterized by energy dispersive spectroscopy (EDS), which verify that the synthesized nanoneedles are composed of zinc, Sb and oxygen. For application point of view, the synthesized nanoneedles were used as photocatalyst for photocatalytic degradation of methylene blue (MBB) and it was found that it exhibit good photocatalytic properties towards the photocatalytic degradation of methylene blue.

  15. Controllable synthesis of hydroxyapatite nanocrystals via a dendrimer-assisted hydrothermal process

    SciTech Connect

    Zhou Zhuohua; Zhou, Ping-Le; Yang Shiping . E-mail: shipingy@shnu.edu.cn; Yu Xibin; Yang Liangzhun

    2007-09-04

    The morphology and size of hydroxyapatite Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2} (denoted HAP) can be controlled under hydrothermal treatment assisted with different dendrimers, such as carboxylic terminated poly(amidoamine) (PAMAM) and polyhydroxy terminated PAMAM. The structure and morphology were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR) and transmission electron microscopy (TEM). IR spectra were also used to investigate the complexation of Ca{sup 2+} with PAMAM. The results revealed that the inner cores of the PAMAM dendrimers are hydrophilic and potentially open to calcium ions, since interior nitrogen moieties serve as complexation sites, especially in case of the polyhydroxy terminated PAMAM. And the reasonable mechanism of crystallization was proposed that it can be attributed to the localization of nucleation site: external or interior PAMAM. Additionally, the PAMAM dendrimer with carboxylic and polyhydroxy groups has an effective influence on the size and shape of hydroxyapatite (HAP) nanostructures. Different crystal morphology was accomplished by adsorption of different dendrimers onto specific faces of growing crystals, altering the relative growth rates of the different crystallographic faces and leading to different crystal habits.

  16. Utilization of recovered nitrogen from hydrothermal carbonization process by Arthrospira platensis.

    PubMed

    Yao, Changhong; Pan, Yanfei; Lu, Hongbin; Wu, Peichun; Meng, Yingying; Cao, Xupeng; Xue, Song

    2016-07-01

    In the context of sustainable cultivation of microalgae, the present study focused on the use of nitrogen from the hot-water extracted biomass residue of Arthrospira platensis by hydrothermal carbonization (HTC) and the sequential cultivation of the same alga with the HTC aqueous phase (AP). Nearly 90% of the nitrogen recovered from HTC into AP was in the organic form. Under nitrogen-limited condition with HTCAP as nitrogen source the yield and content of carbohydrate were enhanced by 21% and 15% respectively compared with that under the same nitrogen level provided by NaNO3, which entitled HTCAP for the substitution of conventional nitrate. In the same way pilot-scale cultivation of A. platensis in raceway ponds outdoors demonstrated that carbohydrate content of 43.8% DW and productivity of 10.3g/m(2)/d was achieved. Notably 54% of organic nitrogen in the HTCAP could be recycled by cultivation of pre-nitrogen starved A. platensis as seeds under nitrogen limitation.

  17. Silica mesostructures: control of pore size and surface area using a surfactant-templated hydrothermal process.

    PubMed

    Ganguly, Aparna; Ahmad, Tokeer; Ganguli, Ashok K

    2010-09-21

    The cooperative self-assembly of the silica precursor, tetraethyl ortho silicate (TEOS), with the surfactant molecule followed by the basic hydrolysis led to the formation of mesoporous silica with varying pore sizes. The pores are formed by the removal of the intermediate assemblies of the charged surfactant molecules. In the absence of formation of such assemblies of surfactants (example in the case of nonionic surfactants), the resulting mesostructures have very small pores, giving low surface area mesostructures. This study outlines the precise control of pore size in a wide size distribution (3.4-22 nm) by the systematic variation of the surfactant. The addition of polyethylene glycol (in situ) while carrying out the hydrolysis of TEOS results in the formation of large-sized cavities (∼40 nm). Uniform spherical particles with pores (different from the cavities) as large as 22 nm and surface areas of ∼1100 m(2)/g have been obtained by the combined effect of the hydrothermal conditions on the cetyl trimethyl ammonium bromide-templated synthesis.

  18. Composition of proteins in okara as a byproduct in hydrothermal processing of soy milk.

    PubMed

    Stanojevic, Sladjana P; Barac, Miroljub B; Pesic, Mirjana B; Vucelic-Radovic, Biljana V

    2012-09-12

    Protein quality, based on its subunit composition, in okara obtained as a byproduct during hydrothermal cooking of soy milk was assessed. The composition of 7S and 11S protein fractions was correlated with the physicochemical properties of protein in okara produced from six soybean varieties. The basic 7S globulin (Bg7S) and 11S protein were two main proteins in okara. Investigated soybean genotypes produced okara with mainly acidic A(5) and basic B(1,2,4) polypeptides of 11S proteins. Soybean 11S content was not an indicator of okara protein recovery or extractability. Of all tested relationships, extractable soluble protein content of okara was influenced only by soybean Bg7S (r = 0.86; p < 0.05) and its light subunit contents (r = 0.93; p < 0.05). Okara protein recovery depended on Bg7S heavy subunit content in soybeans (r = 0.81; p < 0.05). The high quantity of vegetable protein in okara (around 35%) and very high protein extractability (around 85%) qualify this byproduct for potential application in food preparation as a functional ingredient.

  19. Effect of calcination temperature on the photocatalytic reduction and oxidation processes of hydrothermally synthesized titania nanotubes.

    SciTech Connect

    Viayan, B.; Dimitrijevic, N. M.; Rajh, T.; Gray, K.; Northwestern Univ.

    2010-08-05

    Titania nanotubes having diameters 8 to 12 nm and lengths of 50-300 nm were prepared using a hydrothermal method. Further, the titania nanotubes were calcined over the temperature range 200-800 C in order to enhance their photocatalytic properties by altering their morphology. The calcined titania nanotubes were characterized by using X-ray diffraction and surface area analysis and their morphological features were studied by scanning and transmission electron microscopy. Nanotubes calcined at 400 C showed the maximum extent of photocatalyitc reduction of carbon dioxide to methane, whereas samples calcined at 600 C produced maximum photocatalytic oxidation of acetaldehyde. Electron paramagnetic resonance (EPR) spectroscopy was used to interrogate the effects of nanotube structure on the charge separation and trapping as a function of calcination temperature. EPR results indicated that undercoordinated titania sites are associated with maximum CO{sub 2} reduction occurring in nanotubes calcined at 400 C. Despite the collapse of the nantube structure to form nanorods and the concomitant loss of surface area, the enhanced charge separation associated with increased crystallinity promoted high rates of oxidation of acetaldehyde in titania materials calcined at 600 C. These results illustrate that calcination temperature allows us to tune the morphological and surface features of the titania nanostructures for particular photocatalytic reactions.

  20. Towards the kinetics of diagenetic overprint processes deduced from laboratory-based hydrothermal alteration of modern Arctica islandica shell material

    NASA Astrophysics Data System (ADS)

    Casella, Laura A.; Griesshaber, Erika; Mavromatis, Vasileios; Dietzel, Martin; Immenhauser, Adrian; Schmahl, Wolfgang W.

    2016-04-01

    Benthic and nektonic marine biogenic carbonate archives represent the foundation of numerous studies aiming at paleo-environment reconstructions. However, living organisms are not in thermodynamic equilibrium as they form local chemical environments for physiologic processes such as biological mineralization of their hard tissues. This disequilibrium is not sustained after death and all biological tissues are altered by equilibration with the surrounding environment: diagenesis. To understand transformation during diagenesis we performed laboratory-based hydrothermal alteration experiments on Arctica islandica shells at four different temperatures between 100 °C and 175 °C treated in simulated meteoric and burial waters, respectively. We investigated, relative to unaltered shells, the kinetics of Arctica islandica bioaragonite to calcite transition as well as microstructural- and nanostructural characteristics of the altered shells with X-ray diffraction, micro-Raman, high-resolution SEM and EBSD. At hydrothermal treatment at 100 °C bioaragonite - although metastable at 1 bar - does not transform to calcite, even in meteoric fluids and over a time period of 28 days. We noted a drastic recrystallization from the initial fine-grained fractal microstructure and pronounced axial texture to a new and still fine-grained microstructure with an almost randomized orientation distribution. At 175 °C the transformation to coarse-grained calcite is complete after 8 days. Calcite formation starts after a passive incubation period of 4 days; after 6 days the aragonite is almost completely transformed. In solutions simulating meteoric water the grain size of the newly formed calcite reaches 100-150 μm, while in burial fluids the calcite reaches sizes in the 1mm range during 28 days of alteration. Phase transformation proceeds where the hydrothermal fluid is in contact with the aragonite: at shell surfaces, around pores and in growth lines. Our observations lead us to the

  1. Galapagos rift at 86 /sup 0/W: 4. Structure and morphology of hydrothermal fields and their relationship to the volcanic and tectonic processes of the rift valley

    SciTech Connect

    Crane, K.; Ballard, R.D.

    1980-03-10

    The Angus camera system is used to investigate the detailed structure and morphology of the active hydrothermal vent fields of the Galapagos Rift. Precision navigational data are combined with microtopographic information and detailed geological and biological observations obtained from an analysis of the color bottom pictures to create a series of three-dimensional models for each vent field.

  2. Process Design and Economics for the Conversion of Algal Biomass to Hydrocarbons: Whole Algae Hydrothermal Liquefaction and Upgrading

    SciTech Connect

    Jones, Susanne B.; Zhu, Yunhua; Anderson, Daniel B.; Hallen, Richard T.; Elliott, Douglas C.; Schmidt, Andrew J.; Albrecht, Karl O.; Hart, Todd R.; Butcher, Mark G.; Drennan, Corinne; Snowden-Swan, Lesley J.; Davis, Ryan; Kinchin, Christopher

    2014-03-20

    This report provides a preliminary analysis of the costs associated with converting whole wet algal biomass into primarily diesel fuel. Hydrothermal liquefaction converts the whole algae into an oil that is then hydrotreated and distilled. The secondary aqueous product containing significant organic material is converted to a medium btu gas via catalytic hydrothermal gasification.

  3. Mineralogy and Geochemistry of Dacitic domes and associated Cu- Fe-Au Veins occurences during hydrothermal processes, Yazd Province, Iran

    NASA Astrophysics Data System (ADS)

    Sharifi, R.

    2009-04-01

    The Panah-koh Cu-Fe-Au vein deposit, located 60 km south west of Yazd Province, between Central Iranian Zone and Orumieh-Dokhtar tectnomagmatic belt. The vains result from hydrothermal processes related to a Neogenes volcanism which produced a dacitic to rhyodacitic dome which responsible for most of the altration and mineralization in this area. mineralization occurs in a series of NW-SW trending fault planes and breccia zones in (Early Combrian) and sand stone (Percambrian) rocks. the main ore minerals are Chalcopyrite, Pyrite,Arsenopyrite,Hematite,Limonite,Malachite,Azurite, with Quartz,Calcite,Dolomite,Barite and minor Chlorite as the main qanque phases.The Panah- Koh volcanic domes crystallized from an I-Type magma formed in a volcanic arc setting.the volcanic rocks show geochemical evidence of fractionation of Biotite,Hornblande and Fledspars.altration of the minerals in the host rocks suggests pH<5.5 and oxidized conditions.On variation diagrams, MgO, MnO, TiO2, CaO, P2O5, Fe2O3, display negative correlations suggesting that these volcanic rocks experienced fractionation of early-crystallized Biotite, Magnetite, Apatite and Plagioclase. The concentration of Sr, Ni, Ba and V decrease with increasing SiO2 suggesting fractionation of early formed Biotite, K-Feldspar, Magnetite and Plagioclase. supergene effects, with penetration of surface waters along faults and fractures, has led to the oxidation and leaching of the host rocks and the enrichment of copper. Quartz crystals were deposited as layers in crustification banding and comb structures along the walls of veins or the composition of the mineralizing fluids. shallow level of emplacement and low temprature of magma, shows that the hydrothermal system was not able to form a skarn deposit in the Panah-Koh district.

  4. Contrasting hydrological processes of meteoric water incursion during magmatic-hydrothermal ore deposition: An oxygen isotope study by ion microprobe

    NASA Astrophysics Data System (ADS)

    Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Bouvier, Anne-Sophie; Baumgartner, Lukas; Heinrich, Christoph A.

    2016-10-01

    Meteoric water convection has long been recognized as an efficient means to cool magmatic intrusions in the Earth's upper crust. This interplay between magmatic and hydrothermal activity thus exerts a primary control on the structure and evolution of volcanic, geothermal and ore-forming systems. Incursion of meteoric water into magmatic-hydrothermal systems has been linked to tin ore deposition in granitic plutons. In contrast, evidence from porphyry copper ore deposits suggests that crystallizing subvolcanic magma bodies are only affected by meteoric water incursion in peripheral zones and during late post-ore stages. We apply high-resolution secondary ion mass spectrometry (SIMS) to analyze oxygen isotope ratios of individual growth zones in vein quartz crystals, imaged by cathodo-luminescence microscopy (SEM-CL). Existing microthermometric information from fluid inclusions enables calculation of the oxygen isotope composition of the fluid from which the quartz precipitated, constraining the relative timing of meteoric water input into these two different settings. Our results confirm that incursion of meteoric water directly contributes to cooling of shallow granitic plutons and plays a key role in concurrent tin mineralization. By contrast, data from two porphyry copper deposits suggest that downward circulating meteoric water is counteracted by up-flowing hot magmatic fluids. Our data show that porphyry copper ore deposition occurs close to a magmatic-meteoric water interface, rather than in a purely magmatic fluid plume, confirming recent hydrological modeling. On a larger scale, the expulsion of magmatic fluids against the meteoric water interface can shield plutons from rapid convective cooling, which may aid the build-up of large magma chambers required for porphyry copper ore formation.

  5. Fluids in the lithosphere: The dimensions of rheological and hydrothermal processes

    SciTech Connect

    Kerrich, R.K. . Dept. of Geological Sciences)

    1992-01-01

    The lithosphere contains approximately the same mass of water, in the form of pore fluids and hydrates, as the hydrosphere and there is a continuous exchange of volatiles between these reservoirs at a rate of Ca 10[sup 16]/ga. Fluids influence the rheological behavior of the lithosphere over 16 orders of magnitude, from the scale of intracrystalline bonding to the dimensions of entire plates. Pore fluid pressure is one of the major controls on the depth of the seismic-aseismic transition, and at least one major class of ore deposit, namely mesothermal gold, forms dominantly at this rheological transition as a result of fluid pressure fluctuations. A single metallogenic province of this type involves advection of ca 10[sup 18] g of hydrothermal fluid through the seismic-aseismic transition. Sibson and coworkers model of seismic pumping is well established. A major unresolved question, however, is whether surface waters that infiltrate to depth under hydrostatic pressure, become valved off, raised to lithostatic pressure, and discharge, in a cyclic pattern; or alternatively, whether deep crustal fluid reservoirs at lithostatic pressure intermittently breach the seismic-aseismic transition. Another fundamental problem is the depth to which surface fluids penetrate the crust. In the Canadian Shield, tectonic pumping of fluids to depths of 12 km has occurred episodically at 2.6, 2.2, 1.8, 1.1 and 0.5 Ga, involving ca 10[sup 4] km[sup 3] H[sub 2]O per event, during tectonic and/or thermal events, principally along reactivated Archean structures. It is becoming increasingly clear that fluids not only govern rheological behavior, but may also reset radiogenic isotope systems well below the conventional blocking temperature, by solution-reprecipitation, resulting in reversed apparent blocking ages where T(K-Ar) > T(Rb-Sr)>T(Sm-Nd).

  6. Exploring for Volcanic and Hydrothermal Activity Above Off-axis Melt Lenses near the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    White, S. M.; Lee, A. J.; Rubin, K. H.

    2015-12-01

    Two Alvin dives (AL 4771 and 4774) transected the seafloor directly above the two largest Off-Axis Melt Lenses (O-AML) east of the East Pacific Rise (EPR) axis at 9 39'N and 9 54'N. In 2008, a 3D high-resolution seismic reflection survey (MGL-0812) discovered O-AMLs 3-7 km from the EPR at 2-3 km below the seafloor. Several other O-AML in the crust have been subsequently detected in several locations up to 20 km from the spreading axis at fast and intermediate spreading ridges; understanding their impacts is increasingly important. During the dives, no currently active hydrothermal venting or fresh lava was seen, suggesting that these features do not constantly power off-axis geological activity. However, the seafloor appears much younger at small volcanic seamounts in the 9 39'N than at the 9 54'N site. At 9 39'N, we used Alvin to explore the off-axis volcanic mound complex, reaching the summit of the three largest mounds. Although no evidence for on-going hydrothermal or volcanic activity was detected, the seafloor wore a thin sediment layer of ~10cm and thin Mn-coatings on 9 rock samples, suggesting volcanism more recently than would be expected based on the spreading-rate age of the crust. At 9 54'N, the Alvin trackline started south of a prominent abyssal hill, which has an unusual D-shape over 1 km wide in the center, crossed the abyssal hill, visited two local hummocks on top, and then attempted to find volcanic activity on the near slope of EPR axis by going as far west was possible during the dive. Heavy sediment everywhere on the abyssal hill, to the depth of push cores (~30 cm) and probably much deeper in many areas and 4 rock samples from the abyssal hill were quite weathered with little glass intact, suggest that this site is unaffected by the underlying O-AML. Upslope toward the EPR west of the abyssal hill, 4 rocks collected appear somewhat younger, and sediment became thinner. In addition, 3 CTD tow-yos over each O-AML found no evidence of active

  7. Exploring for Volcanic and Hydrothermal Activity Above Off-axis Melt Lenses near the East Pacific Rise

    NASA Astrophysics Data System (ADS)

    West, A. J.; Torres, M. A.; Nealson, K. H.

    2014-12-01

    Two Alvin dives (AL 4771 and 4774) transected the seafloor directly above the two largest Off-Axis Melt Lenses (O-AML) east of the East Pacific Rise (EPR) axis at 9 39'N and 9 54'N. In 2008, a 3D high-resolution seismic reflection survey (MGL-0812) discovered O-AMLs 3-7 km from the EPR at 2-3 km below the seafloor. Several other O-AML in the crust have been subsequently detected in several locations up to 20 km from the spreading axis at fast and intermediate spreading ridges; understanding their impacts is increasingly important. During the dives, no currently active hydrothermal venting or fresh lava was seen, suggesting that these features do not constantly power off-axis geological activity. However, the seafloor appears much younger at small volcanic seamounts in the 9 39'N than at the 9 54'N site. At 9 39'N, we used Alvin to explore the off-axis volcanic mound complex, reaching the summit of the three largest mounds. Although no evidence for on-going hydrothermal or volcanic activity was detected, the seafloor wore a thin sediment layer of ~10cm and thin Mn-coatings on 9 rock samples, suggesting volcanism more recently than would be expected based on the spreading-rate age of the crust. At 9 54'N, the Alvin trackline started south of a prominent abyssal hill, which has an unusual D-shape over 1 km wide in the center, crossed the abyssal hill, visited two local hummocks on top, and then attempted to find volcanic activity on the near slope of EPR axis by going as far west was possible during the dive. Heavy sediment everywhere on the abyssal hill, to the depth of push cores (~30 cm) and probably much deeper in many areas and 4 rock samples from the abyssal hill were quite weathered with little glass intact, suggest that this site is unaffected by the underlying O-AML. Upslope toward the EPR west of the abyssal hill, 4 rocks collected appear somewhat younger, and sediment became thinner. In addition, 3 CTD tow-yos over each O-AML found no evidence of active

  8. New large volume hydrothermal reaction cell for studying chemical processes under supercritical hydrothermal conditions using time-resolved in situ neutron diffraction

    NASA Astrophysics Data System (ADS)

    Ok, Kang Min; O'Hare, Dermot; Smith, Ronald I.; Chowdhury, Mohammed; Fikremariam, Hanna

    2010-12-01

    The design and testing of a new large volume Inconel pressure cell for the in situ study of supercritical hydrothermal syntheses using time-resolved neutron diffraction is introduced for the first time. The commissioning of this new cell is demonstrated by the measurement of the time-of-flight neutron diffraction pattern for TiO2 (Anatase) in supercritical D2O on the POLARIS diffractometer at the United Kingdom's pulsed spallation neutron source, ISIS, Rutherford Appleton Laboratory. The sample can be studied over a wide range of temperatures (25-450 °C) and pressures (1-355 bar). This novel apparatus will now enable us to study the kinetics and mechanisms of chemical syntheses under extreme environments such as supercritical water, and in particular to study the crystallization of a variety of technologically important inorganic materials.

  9. New large volume hydrothermal reaction cell for studying chemical processes under supercritical hydrothermal conditions using time-resolved in situ neutron diffraction.

    PubMed

    Ok, Kang Min; O'Hare, Dermot; Smith, Ronald I; Chowdhury, Mohammed; Fikremariam, Hanna

    2010-12-01

    The design and testing of a new large volume Inconel pressure cell for the in situ study of supercritical hydrothermal syntheses using time-resolved neutron diffraction is introduced for the first time. The commissioning of this new cell is demonstrated by the measurement of the time-of-flight neutron diffraction pattern for TiO(2) (Anatase) in supercritical D(2)O on the POLARIS diffractometer at the United Kingdom's pulsed spallation neutron source, ISIS, Rutherford Appleton Laboratory. The sample can be studied over a wide range of temperatures (25-450 °C) and pressures (1-355 bar). This novel apparatus will now enable us to study the kinetics and mechanisms of chemical syntheses under extreme environments such as supercritical water, and in particular to study the crystallization of a variety of technologically important inorganic materials.

  10. Organic matter in hydrothermal metal ores and hydrothermal fluids

    USGS Publications Warehouse

    Orem, W.H.; Spiker, E. C.; Kotra, R.K.

    1990-01-01

    Massive polymetallic sulfides are currently being deposited around active submarine hydrothermal vents associated with spreading centers. Chemoautolithotrophic bacteria are responsible for the high production of organic matter also associated with modern submarine hydrothermal activity. Thus, there is a significant potential for organic matter/metal interactions in these systems. We have studied modern and ancient hydrothermal metal ores and modern hydrothermal fluids in order to establish the amounts and origin of the organic matter associated with the metal ores. Twenty-six samples from modern and ancient hydrothermal systems were surveyed for their total organic C contents. Organic C values ranged from 0.01% to nearly 4.0% in these samples. Metal ores from modern and ancient sediment-covered hydrothermal systems had higher organic C values than those from modern and ancient hydrothermal systems lacking appreciable sedimentary cover. One massive pyrite sample from the Galapagos spreading center (3% organic C) had stable isotope values of -27.4% (??13C) and 2.1% (??15N), similar to those in benthic siphonophors from active vents and distinct from seep sea sedimentary organic matter. This result coupled with other analyses (e.g. 13C NMR, pyrolysis/GC, SEM) of this and other samples suggests that much of the organic matter may originate from chemoautolithotrophic bacteria at the vents. However, the organic matter in hydrothermal metal ores from sediment covered vents probably arises from complex sedimentary organic matter by hydrothermal pyrolysis. The dissolved organic C concentrations of hydrothermal fluids from one site (Juan de Fuca Ridge) were found to be the same as that of background seawater. This result may indicate that dissolved organic C is effectively scavenged from hydrothermal fluids by biological activity or by co-precipitation with metal ores. ?? 1990.

  11. Massive sulfide deposits and hydrothermal solutions: incremental reaction modeling of mineral precipitation and sulfur isotopic evolution

    SciTech Connect

    Janecky, D.R.

    1986-01-01

    Incremental reaction path modeling of chemical and sulfur isotopic reactions occurring in active hydrothermal vents on the seafloor, in combination with chemical and petrographic data from sulfide samples from the seafloor and massive sulfide ore deposits, allows a detailed examination of the processes involved. This paper presents theoretical models of reactions of two types: (1) adiabatic mixing between hydrothermal solution and seawater, and (2) reaction of hydrothermal solution with sulfide deposit materials. In addition, reaction of hydrothermal solution with sulfide deposit minerals and basalt in feeder zones is discussed.

  12. Calibrated Hydrothermal Parameters, Barrow, Alaska, 2013

    DOE Data Explorer

    Atchley, Adam; Painter, Scott; Harp, Dylan; Coon, Ethan; Wilson, Cathy; Liljedahl, Anna; Romanovsky, Vladimir

    2015-01-29

    A model-observation-experiment process (ModEx) is used to generate three 1D models of characteristic micro-topographical land-formations, which are capable of simulating present active thaw layer (ALT) from current climate conditions. Each column was used in a coupled calibration to identify moss, peat and mineral soil hydrothermal properties to be used in up-scaled simulations. Observational soil temperature data from a tundra site located near Barrow, AK (Area C) is used to calibrate thermal properties of moss, peat, and sandy loam soil to be used in the multiphysics Advanced Terrestrial Simulator (ATS) models. Simulation results are a list of calibrated hydrothermal parameters for moss, peat, and mineral soil hydrothermal parameters.

  13. A reduced crustal magnetization zone near the first observed active hydrothermal vent field on the Southwest Indian Ridge

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Lin, Jian; Chen, Yongshun J.; Tao, Chunhui; German, Christopher R.; Yoerger, Dana R.; Tivey, Maurice A.

    2010-09-01

    Inversion of near-bottom magnetic data reveals a well-defined low crustal magnetization zone (LMZ) near a local topographic high (37°47‧S, 49°39‧E) on the ultraslow-spreading Southwest Indian Ridge (SWIR). The magnetic data were collected by the autonomous underwater vehicle ABE on board R/V DaYangYiHao in February-March 2007. The first active hydrothermal vent field observed on the SWIR is located in Area A within and adjacent to the LMZ at the local topographic high, implying that this LMZ may be the result of hydrothermal alteration of magnetic minerals. The maximum reduction in crustal magnetization is 3 A/M. The spatial extent of the LMZ is estimated to be at least 6.7 × 104 m2, which is larger than that of the LMZs at the TAG vent field on the Mid-Atlantic Ridge (MAR), as well as the Relict Field, Bastille, Dante-Grotto, and New Field vent-sites on the Juan de Fuca Ridge (JdF). The calculated magnetic moment, i.e., the product of the spatial extent and amplitude of crustal magnetization reduction is at least -3 × 107 Am2 for the LMZ on the SWIR, while that for the TAG field on the MAR is -8 × 107 Am2 and that for the four individual vent fields on the JdF range from -5 × 107 to -3 × 107 Am2. Together these results indicate that crustal demagnetization is a common feature of basalt-hosted hydrothermal vent fields at mid-ocean ridges of all spreading rates. Furthermore, the crustal demagnetization of the Area A on the ultraslow-spreading SWIR is comparable in strength to that of the TAG area on the slow-spreading MAR.

  14. Timing and duration of hydrothermal activity at the Los Bronces porphyry cluster: an update

    NASA Astrophysics Data System (ADS)

    Deckart, K.; Silva, W.; Spröhnle, C.; Vela, I.

    2014-06-01

    New geochronological data from the Los Bronces cluster of the Río Blanco-Los Bronces mega-porphyry Cu-Mo district establish a wide range of magmatism, hydrothermal alteration, and mineralization ages, both in terms of areal extent and time. The northern El Plomo and southernmost Los Piches exploration areas contain the oldest barren porphyritic intrusions with U-Pb ages of 10.8 ± 0.1 Ma and 13.4 ± 0.1 Ma, respectively. A hypabyssal barren intrusion adjacent northwesterly to the main pit area yields a slightly younger age of 10.2 ± 0.3 Ma (San Manuel sector, U-Pb), whereas in the Los Bronces (LB) open-pit area, the present day mineral extraction zone, porphyries range from 8.49 to 6.02 Ma (U-Pb). Hydrothermal biotite and sericite ages are up to 0.5 Ma younger but consistent with the cooling of the corresponding intrusion events of each area. Two quartz-molybdenite B-type veins from the LB open pit have Re-Os molybdenite ages of 5.65 ± 0.03 Ma and 5.35 ± 0.03 Ma consistent with published data for the contiguous Río Blanco cluster. The San Manuel exploration area within the Los Bronces cluster, located about 1.5-2 km southeast of the open-pit extraction zone, shows both the oldest hydrothermal biotite (7.70 ± 0.07 Ma; 40Ar/39Ar) and breccia cement molybdenite ages (8.36 ± 0.06 Ma; Re-Os) registered in the entire Río Blanco-Los Bronces district. These are also older than those reported from the El Teniente porphyry Cu(-Mo) deposit, suggesting that mineralization in the late Miocene to early Pliocene porphyry belt of Central Chile commenced 2 Ma before the previously accepted age of 6.3 Ma.

  15. Enhanced Visible-Light Photocatalytic Activity of C/Ce-Codoped ZnO Nanoellipsoids Synthesized by Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Ha, Luu Thi Viet; Dai, Luu Minh; Nhiem, Dao Ngoc; Van Cuong, Nguyen

    2016-08-01

    C/Ce-codoped ZnO nanomaterial has been synthesized by a hydrothermal method and its physical properties and characterization investigated using thermogravimetric and differential thermal analysis (TG-DTA), x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive x-ray (EDX) spectroscopy, UV-Vis diffuse reflectance spectroscopy, and scanning electron microscopy (SEM). The photocatalytic activity of the nanomaterial was examined using methylene blue as organic dye under visible-light source. The results show that the C/Ce-codoped ZnO nanomaterial exhibited higher photocatalytic activity under visible-light irradiation compared with undoped ZnO, Ce-doped ZnO or C-doped ZnO nanomaterials. Such enhancement of the photocatalytic activity of C/Ce-codoped ZnO under visible-light irradiation suggests that these nanoparticles might have good applications in optoelectronics and wastewater treatment.

  16. Geochemistry of hydrothermal plume in the Suiyo Seamount Caldera.

    NASA Astrophysics Data System (ADS)

    Shitashima, K.; Maeda, Y.

    2002-12-01

    Chemical compounds of the hot basalt origin are discharged into the deep ocean via hydrothermal plume by the deep-sea hydrothermal activity. The hydrothermal plume is widely diffused to the ocean by mixing with ambient seawater. Chemical reactions and interactions with microorganisms in the diffusion process of the hydrothermal plume are important to comprehend the oceanic geochemical cycles. Recently, it has been clarified that the variation of hydrothermal activity is greatly controlled in the tidal current. Not only geochemical observation but also physical observation, such as water current measurement, are necessary for the understanding of the deep-sea hydrothermal systems including the behavior of hydrothermal plume. In order to observe the diffusion process of hydrothermal plumes, sampling and chemical mapping of the hydrothermal plume and measurement of water current were carried out at the Suiyo Seamount Caldera during research cruises under the ?Archaean Park? project funded by MEXT. The three-dimensional acoustic current meters were moored at the height of 13m and 125m above the bottom in the Suiyo Seamount Caldera. At the 13m height, average water current speed and current direction were 10.46 cm/second and 228.1 degrees, respectively, and maximum water current speed was over 40.46 cm/second. On the other hand, average water current speed and current direction at the 125m height were 3.87 cm/second and 57.8 degrees, respectively. The strong water current of the southwest direction in 24 hours periods existed near bottom of the caldera. In addition, downward current and water temperature depreciation were observed, when there was the strong current in 24 hours periods. These results suggest that the low-temperature ocean water around the Suiyo Seamount flows toward the bottom of caldera periodically. The mini CTDT-RMS mounted twelve 1.2L Niskin bottles and the in-situ pH sensor were installed on the ROV or manned submersible. The hydrothermal plume

  17. Conversion of tomato-peel waste into solid fuel by hydrothermal carbonization: Influence of the processing variables.

    PubMed

    Sabio, E; Álvarez-Murillo, A; Román, S; Ledesma, B

    2016-01-01

    In this work, the influence of the variables temperature, residence time, and biomass/water ratio on the hydrothermal carbonization (HTC) of tomato peel was investigated. The implementation of a Design of Experiments - Response Surface Methodology approach allowed to identify the importance of each variable, as well as their interactions, in both the reactivity (solid yield) and energy densification (increase in higher heating value). The HTC residence time and specially temperature had a major effect on the process, increasing the solid yield and promoting energy densification. Ratio had a minor effect although under certain temperature and time conditions, it was a decisive parameter. Solid yields in the range 27.6% and 87.7% with corresponding high heating values 23.6-34.6 MJ kg(-1) were obtained. From the statistical processing of the experimental data obtained pseudo-second order models were developed. It was proven that these approaches envisaged the hydrochar final characteristics successfully. From the elemental analysis and the FTIR spectra, it was possible to investigate the HTC pathway, which was defined as a combination of several processes; considering dehydration and decarboxylation reactions and especially lignin depolimerization reactions, which lead to the formation of monomeric radicals. Moreover, the surface morphology of selected hydrochars by Scanning Electron Microscopy (SEM) showed the original structure scaffold, with minor changes between hydrochars prepared under different conditions.

  18. Geochemical Evidence for Submarine Hydrothermal Activity in the Gulf of Aden, Northwestern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Gamo, T.; Hasumoto, H.; Okamura, K.; Hatanaka, H.; Mori, M.; Chinen, M.; Tanaka, J.; Komatsu, D.; Tamaki, K.; Fujimoto, H.; Tsunogai, U.; Kouzuma, F.; Hirota, A.

    2001-12-01

    We searched for hydrothermal plumes along spreading axes in the Gulf of Aden, between 45\\deg36'E and 52\\deg42'E, using a CTD multi-water sampling system, mapping water column distributions of light transmission and chemical tracers (Mn, Fe, CH4 etc.) in December 2000 and January 2001. In addition to water sampling for chemical analysis, an in-situ chemical analyzer GAMOS was attached to the CTD-system to conduct tow-yo observations. We found typical hydrothermal plumes (anomalies of light transmission and chemical tracers) at 600-800 m depth over twin peak seamounts (60 miles southeast of Aden) which may be hot spot volcanoes associated with the Afar mantle plume. Strong light transmission anomalies imply the existence of black smoker fluids. The maximum concentrations of Mn, Fe, and CH4 are 46 nM, 251 nM, and 15 nM, respectively. An estimated \\delta13C(CH4) value for an endmember fluid of approximately -15\\permil indicates magmatic CH4 with little contribution of CH4 from organic material decomposition in sediments.

  19. Hydrothermal activity on the southern Mid-Atlantic Ridge: Tectonically- and volcanically-controlled venting at 4 5°S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Murton, B. J.; Parson, L. M.; Prien, R. D.; Ramirez-Llodra, E.; Jakuba, M.; Shank, T. M.; Yoerger, D. R.; Baker, E. T.; Walker, S. L.; Nakamura, K.

    2008-09-01

    We report results from an investigation of the geologic processes controlling hydrothermal activity along the previously-unstudied southern Mid-Atlantic Ridge (3-7°S). Our study employed the NOC (UK) deep-tow sidescan sonar instrument, TOBI, in concert with the WHOI (USA) autonomous underwater vehicle, ABE, to collect information concerning hydrothermal plume distributions in the water column co-registered with geologic investigations of the underlying seafloor. Two areas of high-temperature hydrothermal venting were identified. The first was situated in a non-transform discontinuity (NTD) between two adjacent second-order ridge-segments near 4°02'S, distant from any neovolcanic activity. This geologic setting is very similar to that of the ultramafic-hosted and tectonically-controlled Rainbow vent-site on the northern Mid-Atlantic Ridge. The second site was located at 4°48'S at the axial-summit centre of a second-order ridge-segment. There, high-temperature venting is hosted in an ˜ 18 km 2 area of young lava flows which in some cases are observed to have flowed over and engulfed pre-existing chemosynthetic vent-fauna. In both appearance and extent, these lava flows are directly reminiscent of those emplaced in Winter 2005-06 at the East Pacific Rise, 9°50'N and reference to global seismic catalogues reveals that a swarm of large (M 4.6-5.6) seismic events was centred on the 5°S segment over a ˜ 24 h period in late June 2002, perhaps indicating the precise timing of this volcanic eruptive episode. Temperature measurements at one of the vents found directly adjacent to the fresh lava flows at 5°S MAR (Turtle Pits) have subsequently revealed vent-fluids that are actively phase separating under conditions very close to the Critical Point for seawater, at ˜ 3000 m depth and 407 °C: the hottest vent-fluids yet reported from anywhere along the global ridge crest.

  20. Hydrothermal mineralization at seafloor spreading centers

    NASA Astrophysics Data System (ADS)

    Rona, Peter A.

    1984-01-01

    The recent recognition that metallic mineral deposits are concentrated by hydrothermal processes at seafloor spreading centers constitutes a scientific breakthrough that opens active sites at seafloor spreading centers as natural laboratories to investigate ore-forming processes of such economically useful deposits as massive sulfides in volcanogenic rocks on land, and that enhances the metallic mineral potential of oceanic crust covering two-thirds of the Earth both beneath ocean basins and exposed on land in ophiolite belts. This paper reviews our knowledge of processes of hydrothermal mineralization and the occurrence and distribution of hydrothermal mineral deposits at the global oceanic ridge-rift system. Sub-seafloor hydrothermal convection involving circulation of seawater through fractured rocks of oceanic crust driven by heat supplied by generation of new lithosphere is nearly ubiquitous at seafloor spreading centers. However, ore-forming hydrothermal systems are extremely localized where conditions of anomalously high thermal gradients and permeability increase hydrothermal activity from the ubiquitous low-intensity background level (⩽ 200°C) to high-intensity characterized by high temperatures ( > 200-c.400°C), and a rate and volume of flow sufficient to sustain chemical reactions that produce acid, reducing, metal-rich primary hydrothermal solutions. A series of mineral phases with sulfides and oxides as high- and low-temperature end members, respectively, are precipitated along the upwelling limb and in the discharge zone of single-phase systems as a function of increasing admixture of normal seawater. The occurrence of hydrothermal mineral deposits is considered in terms of spatial and temporal frames of reference. Spatial frames of reference comprise structural features along-axis (linear sections that are the loci of seafloor spreading alternating with transform faults) and perpendicular to axis (axial zone of volcanic extrusion and marginal

  1. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano.

    PubMed

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d'Ars, Jean; Komorowski, Jean-Christophe

    2016-09-15

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 10(6) m(3) to 7 × 10(6) m(3). However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [-0.8;-0.4] × 10(9) kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 10(9) kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir.

  2. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano

    PubMed Central

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond d’Ars, Jean; Komorowski, Jean-Christophe

    2016-01-01

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [−0.8;−0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir. PMID:27629497

  3. Muon dynamic radiography of density changes induced by hydrothermal activity at the La Soufrière of Guadeloupe volcano

    NASA Astrophysics Data System (ADS)

    Jourde, Kevin; Gibert, Dominique; Marteau, Jacques; de Bremond D’Ars, Jean; Komorowski, Jean-Christophe

    2016-09-01

    Imaging geological structures through cosmic muon radiography is a newly developed technique which shows a great potential in volcanology. Here we demonstrate that muon radiography permits to detect and characterize mass movements in shallow hydrothermal systems of low-energy active volcanoes like the La Soufrière lava dome. We present an experiment conducted on this volcano during the Summer 2014 and bring evidence that very important density changes occurred in three domains of the lava dome. Depending on their position and on the medium porosity the volumes of these domains vary from 1 × 106 m3 to 7 × 106 m3. However, the total mass budget remains approximately constant : two domains show a mass loss (Δm∈ [‑0.8‑0.4] × 109 kg) and the third one a mass gain (Δm∈ [1.5; 2.5] × 109 kg). We attribute the negative mass changes to the formation of steam in shallow hydrothermal reservoir previously partly filled with liquid water. This coincides with the emergence of new fumaroles on top of the volcano. The positive mass change is synchronized with the negative mass changes indicating that liquid water probably flowed from the two reservoirs invaded by steam toward the third reservoir.

  4. Production of acetic acid by hydrothermal two-step process of vegetable wastes for use as a road deicer

    NASA Astrophysics Data System (ADS)

    Jin, F.; Watanabe, Y.; Kishita, A.; Enomoto, H.; Kishida, H.

    2008-07-01

    This study aimed to produce acetic acid from vegetable wastes by a new hydrothermal two-step process. A continuous flow reaction system with a maximum treatment capacity of 2 kg/h of dry biomass developed by us was used. Five kinds of vegetables of carrots, white radish, chinese cabbage, cabbage and potato were selected as the representation of vegetable wastes. First, batch experiments with the selected vegetables were performed under the condition of 300°C, 1 min for the first step, and 300°C, 1 min and 70% oxygen supply for the second step, which is the optimum condition for producing acetic acid in the case of using starch as test material. The highest yields of acetic acid from five vegetables were almost the same as those obtained from starch. Subsequently, similar the highest yield of acetic acid and experimental conditions from vegetables were also obtained successfully using the continuous flow reaction system. These results should be useful for developing an industrial scale process.

  5. Photoluminescence on cerium-doped ZnO nanorods produced under sequential atomic layer deposition-hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Cervantes-López, J. L.; Rangel, R.; Espino, J.; Martínez, E.; García-Gutiérrez, R.; Bartolo-Pérez, P.; Alvarado-Gil, J. J.; Contreras, O. E.

    2017-01-01

    Doped and undoped ZnO nanorod arrays were produced combining atomic layer deposition and hydrothermal processes. First, a ZnO layer with preferential orientation normal to the c-axis was grown on the substrate by means of the decomposition of diethylzinc; subsequently, the nanorod arrays were produced through solvothermal process using a solution of Zn(NO3)2 as precursor. Doped ZnO nanorods were produced using Ce(C2H3O2)3·H2O as dopant agent precursor. Undoped and Ce-doped ZnO nanorod arrays showed high-intensity photoluminescence. The doping concentration of x = 0.04 (Zn1- x Ce x O) displayed the highest photoluminescence. Undoped ZnO showed an intense UV peak centered at 382 nm with a narrow full wide half maximum of 33 nm. Ce-doped ZnO PL spectra contain three bands, one signal in the UV region centered at 382 nm, other centered at 467 nm in the near-green region and other one emission centered at 560 nm. The results herein exposed demonstrate the capability to produce high-quality ZnO and Zn1- x Ce x O films.

  6. Effects of hydrothermal processes on antioxidants in brown, purple and red bran whole grain rice (Oryza sativa L.).

    PubMed

    Min, Byungrok; McClung, Anna; Chen, Ming-Hsuan

    2014-09-15

    The impacts of parboiling and wet-cooking, alone and in combination, on the concentrations of lipophilic antioxidants (vitamin E and γ-oryzanol), soluble (including proanthocyanidins and anthocyanins) and cell wall-bound phenolics, and antioxidant capacities in whole grain rice from six cultivars having different bran colours were investigated. Parboiling rough and brown rice increased the concentrations of lipophilic antioxidants in whole grain rice but decreased the concentrations of total phenolics and antioxidant capacities found in the soluble fraction. After hydrothermal processing of purple bran rice, the retention of extractable anthocyanins was low, but was high for simple phenolics. For proanthocyanidins found in red bran rice, the extractable oligomers with a degree of polymerization (DP) less than 4, increased up to 6-fold; while for oligomers with DP⩾4 and polymers, there was a significant decrease that was positively correlated with the DP and the temperature of the processing methods. The presence of hulls helped to retain water-soluble antioxidants during parboiling.

  7. A national drilling program to study the roots of active hydrothermal systems related to young magmatic intrusions

    SciTech Connect

    Not Available

    1984-01-01

    The importance of studies of active hydrothermal-magma systems as part of a national continental scientific drilling program has been emphasized in numerous workshops and symposia. The present report, prepared by the Panel on Thermal Regimes of the Continental Scientific Drilling Committee, both reinforces and expands on earlier recommendations. The US Geodynamics Committee 1979 report of the Los Almos workshop, Continental Scientific Drilling Program, placed major emphasis on maximizing the scientific value of current and planned drilling by industry and government, supplementing these efforts with holes drilled solely for scientific purposes. Although the present report notes the importance of opportunities for scientific investigations that may be added on to current, mission-oriented drilling activities, the Panel on Thermal Regimes recognizes that such opportunities are limited and thus focused its study on holes dedicated to broad scientific objectives. 16 refs., 2 figs., 4 tabs.

  8. Geochemistry of fluid phases and sediments: Relevance to hydrothermal circulation in Middle Valley, ODP Legs 139 and 169

    USGS Publications Warehouse

    Gieskes, J.M.; Simoneit, B.R.T.; Shanks, Wayne C.; Goodfellow, W.D.; James, R.H.; Baker, P.A.; Ishibashi, J.-I.

    2002-01-01

    Geochemical and isotopic studies of pore fluids and solid phases recovered from the Dead Dog and Bent Hill hydrothermal sites in Middle Valley (Ocean Drilling Program Leg 169) have been compared with similar data obtained previously from these sites during Ocean Drilling Program Leg 139. Although generally the hydrothermal systems reflect non-steady state conditions, the data allow an assessment of the history of the hydrothermal processes. Sediment K/A1 ratios as well as the distribution of anhydrite in the sediments suggest that the Dead Dog hydrothermal field has been, and still is, active. In contrast, similar data in the Bent Hill hydrothermal field indicate a waning of hydrothermal activity. Pore fluid and hydrothermal vent data in the Dead Dog hydrothermal field are similar in nature to the data collected during ODP Leg 139. In the area of the Bent Hill sulfide deposit, however, the pore water data indicate that recent wholesale flushing of the sediment column with relatively unaltered seawater has obliterated a previous record of hydrothermal activity in the pore fluids. Data from the deepest part of Hole 1035A in the Bent Hill locality show the presence of hydrothermal fluids at greater depths in this area. This suggests the origin of the hydrothermal fluids found to be emanating from Hole 1035F, which constitutes one of the first man made hydrothermal vents in the Middle Valley hydrothermal system. Similarly, CORKed Hole 858G, because of seal failures, has acted as a hydrothermal vent, with sulfide deposits forming inside the CORK. ?? 2002 Elsevier Science Ltd. All rights reserved.

  9. Hydrothermal fluids circulation and travertine deposition in an active tectonic setting: Insights from the Kamara geothermal area (western Anatolia, Turkey)

    NASA Astrophysics Data System (ADS)

    Brogi, Andrea; Alçiçek, M. Cihat; Yalçıner, Cahit Çağlar; Capezzuoli, Enrico; Liotta, Domenico; Meccheri, Marco; Rimondi, Valentina; Ruggieri, Giovanni; Gandin, Anna; Boschi, Chiara; Büyüksaraç, Aydin; Alçiçek, Hülya; Bülbül, Ali; Baykara, Mehmet Oruç; Shen, Chuan-Chou

    2016-06-01

    Coexistence of thermal springs, travertine deposits and tectonic activity is a recurring feature for most geothermal areas. Although such a certainty, their relationships are debated mainly addressing on the role of the tectonic activity in triggering and controlling fluids flow and travertine deposition. In this paper, we present the results of an integrated study carried out in a geothermal area located in western Anatolia (Turkey), nearby the well-known Pamukkale area (Denizli Basin). Our study focused on the relationships among hydrothermal fluids circulation, travertine deposition and tectonic activity, with particular emphasis on the role of faults in controlling fluids upwelling, thermal springs location and deposition of travertine masses. New field mapping and structural/kinematics analyses allowed us to recognize two main faults systems (NW- and NE-trending), framed in the Neogene-Quaternary extensional tectonic evolution of western Anatolia. A geo-radar (GPR) prospection was also provided in a key-area, permitting us to reconstruct a buried fault zone and its relationships with the development of a fissure-ridge travertine deposit (Kamara fissure-ridge). The integration among structural and geophysical studies, fluids inclusion, geochemical, isotopic data and 230 Th/238 U radiometric age determination on travertine deposits, depict the characteristics of the geothermal fluids and their pathway, up to the surface. Hydrological and seismological data have been also taken in account to investigate the relation between local seismicity and fluid upwelling. As a main conclusion we found strict relationships among tectonic activity, earthquakes occurrence, and variation of the physical/chemical features of the hydrothermal fluids, presently exploited at depth, or flowing out in thermal springs. In the same way, we underline the tectonic role in controlling the travertine deposition, making travertine (mainly banded travertine) a useful proxy to reconstruct the

  10. River solute fluxes reflecting active hydrothermal chemical weathering of the Yellowstone Plateau Volcanic Field, USA

    USGS Publications Warehouse

    Hurwitz, S.; Evans, William C.; Lowenstern, J. B.

    2010-01-01

    In the past few decades numerous studies have quantified the load of dissolved solids in large rivers to determine chemical weathering rates in orogenic belts and volcanic areas, mainly motivated by the notion that over timescales greater than ~100kyr, silicate hydrolysis may be the dominant sink for atmospheric CO2, thus creating a feedback between climate and weathering. Here, we report the results of a detailed study during water year 2007 (October 1, 2006 to September 30, 2007) in the major rivers of the Yellowstone Plateau Volcanic Field (YPVF) which hosts Earth's largest "restless" caldera and over 10,000 thermal features. The chemical compositions of rivers that drain thermal areas in the YPVF differ significantly from the compositions of rivers that drain non-thermal areas. There are large seasonal variations in river chemistry and solute flux, which increases with increasing water discharge. The river chemistry and discharge data collected periodically over an entire year allow us to constrain the annual solute fluxes and to distinguish between low-temperature weathering and hydrothermal flux components. The TDS flux from Yellowstone Caldera in water year 2007 was 93t/km2/year. Extensive magma degassing and hydrothermal interaction with rocks accounts for at least 82% of this TDS flux, 83% of the cation flux and 72% of the HCO3- flux. The low-temperature chemical weathering rate (17t/km2/year), calculated on the assumption that all the Cl- is of thermal origin, could include a component from low-temperature hydrolysis reactions induced by CO2 ascending from depth rather than by atmospheric CO2. Although this uncertainty remains, the calculated low-temperature weathering rate of the young rhyolitic rocks in the Yellowstone Caldera is comparable to the world average of large watersheds that drain also more soluble carbonates and evaporates but is slightly lower than calculated rates in other, less-silicic volcanic regions. Long-term average fluxes at

  11. Hierarchically nanostructured hydroxyapatite: hydrothermal synthesis, morphology control, growth mechanism, and biological activity

    PubMed Central

    Ma, Ming-Guo

    2012-01-01

    Hierarchically nanosized hydroxyapatite (HA) with flower-like structure assembled from nanosheets consisting of nanorod building blocks was successfully synthesized by using CaCl2, NaH2PO4, and potassium sodium tartrate via a hydrothermal method at 200°C for 24 hours. The effects of heating time and heating temperature on the products were investigated. As a chelating ligand and template molecule, the potassium sodium tartrate plays a key role in the formation of hierarchically nanostructured HA. On the basis of experimental results, a possible mechanism based on soft-template and self-assembly was proposed for the formation and growth of the hierarchically nanostructured HA. Cytotoxicity experiments indicated that the hierarchically nanostructured HA had good biocompatibility. It was shown by in-vitro experiments that mesenchymal stem cells could attach to the hierarchically nanostructured HA after being cultured for 48 hours. Objective The purpose of this study was to develop facile and effective methods for the synthesis of novel hydroxyapatite (HA) with hierarchical nanostructures assembled from independent and discrete nanobuilding blocks. Methods A simple hydrothermal approach was applied to synthesize HA by using CaCl2, NaH2PO4, and potassium sodium tartrate at 200°C for 24 hours. The cell cytotoxicity of the hierarchically nanostructured HA was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Results HA displayed the flower-like structure assembled from nanosheets consisting of nanorod building blocks. The potassium sodium tartrate was used as a chelating ligand, inducing the formation and self-assembly of HA nanorods. The heating time and heating temperature influenced the aggregation and morphology of HA. The cell viability did not decrease with the increasing concentration of hierarchically nanostructured HA added. Conclusion A novel, simple and reliable hydrothermal route had been developed for the synthesis of

  12. The Hydrothermal System at the Grand Canyon of the Yellowstone River: Exposed and Hidden

    NASA Astrophysics Data System (ADS)

    Jaworowski, C.; Heasler, H. P.; Susong, D. D.; Neale, C. M.; Sivarajan, S.; Masih, A.

    2012-12-01

    Combining calibrated and corrected night-time, airborne thermal infrared imaging with field information from the 2008 drilling of the Canyon borehole strainmeter (B206) in Yellowstone National Park emphasizes the extensive nature of Yellowstone's hydrothermal system. Both studies contributed to an understanding of the vertical and horizontal flow of heat and fluids through the bedrock in this area. Night-time, airborne thermal infrared imagery, corrected for emissivity and atmosphere clearly shows north-trending faults and fractures transmitting heat and fluids through the rhyolitic bedrock and into the overlying glacial sediments near the Canyon borehole. Along the Grand Canyon of the Yellowstone, the Clear Lake hydrothermal area is an example of hydrothermal alteration at the ground surface. The numerous hydrothermal features exposed in the nearby Grand Canyon of the Yellowstone River and its hydrothermally altered walls are clear evidence of the exposed hydrothermal system. The bedrock geology, geologic processes, and hydrothermal activity combined to form the dramatic Grand Canyon of the Yellowstone. The night-time thermal infrared imagery provides a new view of this exposed hydrothermal system for scientists and visitors. Scientists and Yellowstone Park managers carefully sited the Canyon borehole strainmeter in a green, grassy meadow to insure successful completion of the borehole in a non-hydrothermal area. The closest hydrothermal feature to the drilling site was about 2.5 km to the east. Although excellent exposures of hydrothermal altered bedrock are present about 1.5 km east at the Lower Falls and the Grand Canyon of the Yellowstone River, the connection between exposed hydrothermal areas and the borehole site was not obvious. After drilling through 9 m of brown-gray muds and 113 m of rock, a bottom hole temperature of 81.2 degrees Celsius precluded drilling the hole any deeper than 122 m. The post-drilling data collected from B206 and the airborne

  13. Influence of hydrothermal processes on changes of volcanic rocks (data of physical modelling)

    NASA Astrophysics Data System (ADS)

    Shanina, V. V.; Bychkov, A. Y.

    2009-04-01

    Due to active development of geothermal energy, in middle of the last century have begun papers devoted to experiments, directed on study of transformations of minerals [4] and rocks [1, 2, 5] under action of geothermal processes. But any researcher did not estimate thus change of their physical and physico-mechanical properties. The purpose of job - to study character and dynamics changes of volcanic rocks (to simulate conditions of geothermal transformations). Tasks: creation of the whole series of experiments in autoclavs at various temperatures, pressure and composition of solutions, preparation of samples, study of chemical and mineral composition, structure and properties of rocks and solutions before and after experiments. In 2006 the first similar experiments were begun [3]. Researched rocks basalts, hyaloclasites and obsidian, selected from Iceland and tuffs Payzhetka Geothermal Field, Southern Kamchatka, Russia. Were used autoclavs, consisting from titanic of an alloy ВТ-8, volume 116-119 мл, in each of which was located from 2 up to 4 samples of rocks of the investigated structure and properties. The heating was made in OVEN ТРМ-10 with accuracy + 1 °С, the constancy of temperature was supervised by thermocouples. 15 experiences (temperature 200, 300 and 450 °С; pressure 16, 86 and 1000 bars accordingly now are carried out; 4 solutions (1 alkaline and 3 acid); duration 14, 15, 30 and 60 days). All four groups of the investigated rocks appreciablly react under geothermal influence. The changes are observed in colour of samples (brighten in acid solutions), their microstructure, that for basalts is visible only in raster electronic microscope, and in education of new mineral phases, is especially active in a acid solution, the X-Ray analysis (has executed by Dr. Krupskaya V.V., apparatuses - DRON- UM1) has shown, that 94,2 % is smectite, 3,5 % - kaolinite, 1,2 % - crisrobalite, 1,1 % - diopside (?), in others pores fills chlorite, and in an

  14. Preparation of ultrafine catalyst powders using a flow-through hydrothermal process

    SciTech Connect

    Matson, D.W.; Linehan, J.C.; Darab, J.G.

    1993-03-01

    The rapid thermal decomposition of solutes (RTDS) process was used to produce ultrafine iron-bearing oxide and hydroxide powders for use as coal liquefaction catalysts. The RTDS process subjects aqueous solutions containing dissolved metal salts to elevated temperatures and pressures in a flow-through apparatus. Particle formation is initiated during brief exposure of the solution to a heated region, then is quenched by abruptly cooling and depressurizing the suspension. Powders having individual crystallites on the nanometer to tens-of-nanometer size scale are readily produced by the RTDS method. Variations in RTDS processing parameters (e.g., solute concentration, flow rate, processing temperature) affect the crystallinity, morphology, and size of particles produced. Powders generated using the RTDS process were characterized using XRD, EXAFS, electron microscopy, Mossbauer spectroscopy, and BET surface area analysis.

  15. Evidence of hydrothermal activity on Marsili Seamount, Tyrrhenian Basin. Technical report

    SciTech Connect

    Uchupi, E.; Ballard, R.D.

    1989-01-01

    In this paper we describe the finding of what appears to be an extensive hydrothermal mineral deposit on the crest of Marsili Seamount in the Tyrrhenian Basin, western Mediterranean Sea. The deposit on the seamount was discovered during a study of the geology of the Tyrrhenian Basin with the Argo video system (HARRIS and BALLARD, 1986) aboard the R.V. Starella during June 1988. Mounted on the vehicle were three Silicon Intensified target (SIT) cameras, a digital charge Couple Device (CCD) camera and a 35 mm camera with a 16 mm lens. The site was revisited in mid August aboard the R.V. Knorr during a cruise to test the dynamic position system on the Knorr.

  16. Influence of pH on hydrothermal treatment of swine manure: Impact on extraction of nitrogen and phosphorus in process water.

    PubMed

    Ekpo, U; Ross, A B; Camargo-Valero, M A; Fletcher, L A

    2016-08-01

    This study investigates the influence of pH on extraction of nitrogen and phosphorus from swine manure following hydrothermal treatment. Conditions include thermal hydrolysis (TH) at 120°C and 170°C, and hydrothermal carbonisation (HTC) at 200°C and 250°C in either water alone or in the presence of 0.1M NaOH, H2SO4, CH3COOH or HCOOH. Phosphorus extraction is pH and temperature dependent and is enhanced under acidic conditions. The highest level of phosphorus is extracted using H2SO4 reaching 94% at 170°C. The phosphorus is largely retained in the residue for all other conditions. The extraction of nitrogen is not as significantly influenced by pH, although the maximum N extraction is achieved using H2SO4. A significant level of organic-N is extracted into the process waters following hydrothermal treatment. The results indicate that operating hydrothermal treatment in the presence of acidic additives has benefits in terms of improving the extraction of phosphorus and nitrogen.

  17. Hydrothermal microwave processing of microalgae as a pre-treatment and extraction technique for bio-fuels and bio-products.

    PubMed

    Biller, Patrick; Friedman, Cerri; Ross, Andrew B

    2013-05-01

    Microalgae are regarded as a promising source of lipids for bio-diesel production and bio-products. The current paper investigates the processing of microalgal slurries under controlled microwave irradiation. Microwave power was applied to reach temperatures of 80, 100, 120 and 140 °C at a constant residence time of 12 min. Microwave irradiation led to disruption of the algal cell walls which facilitated lipid extraction. The influence of inorganic material on microwave heating was assessed for three strains including, Nannochloropsis occulata, Chlorogloeopsis fritschii and Pseudochoricystis ellipsoidea. Mass balances were calculated and showed that the amount of carbon, nitrogen and total mass recovered in the residue was highly dependent on process conditions and algae strain. Hydrothermal microwave processing (HMP) was found to be an effective pre-treatment for hydrothermal liquefaction and extraction of lipids and phytochemicals.

  18. Observation of hydrothermal flows with acoustic video camera

    NASA Astrophysics Data System (ADS)

    Mochizuki, M.; Asada, A.; Tamaki, K.; Scientific Team Of Yk09-13 Leg 1

    2010-12-01

    To evaluate hydrothermal discharging and its diffusion process along the ocean ridge is necessary for understanding balance of mass and flux in the ocean, ecosystem around hydrothermal fields and so on. However, it has been difficult for us to measure hydrothermal activities without disturbance caused by observation platform ( submersible, ROV, AUV ). We wanted to have some observational method to observe hydrothermal discharging behavior as it was. DIDSON (Dual-Frequency IDentification SONar) is acoustic lens-based sonar. It has sufficiently high resolution and rapid refresh rate that it can substitute for optical system in turbid or dark water where optical systems fail. DIDSON operates at two frequencies, 1.8MHz or 1.1MHz, and forms 96 beams spaced 0.3° apart or 48 beams spaced 0.6° apart respectively. It images out to 12m at 1.8MHz and 40m at 1.1MHz. The transmit and receive beams are formed with acoustic lenses with rectangular apertures and made of polymethylpentene plastic and FC-70 liquid. This physical beam forming allows DIDSON to consume only 30W of power. DIDSON updates its image between 20 to 1 frames/s depending on the operating frequency and the maximum range imaged. It communicates its host using Ethernet. Institute of Industrial Science, University of Tokyo ( IIS ) has understood DIDSON’s superior performance and tried to find new method for utilization of it. The observation systems that IIS has ever developed based on DIDSON are waterside surveillance system, automatic measurement system for fish length, automatic system for fish counting, diagnosis system for deterioration of underwater structure and so on. A next challenge is to develop an observation method based on DIDSON for hydrothermal discharging from seafloor vent. We expected DIDSON to reveal whole image of hydrothermal plume as well as detail inside the plume. In October 2009, we conducted seafloor reconnaissance using a manned deep-sea submersible Shinkai6500 in Central Indian

  19. Preparation and photocatalytic activity of Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} from complex precursor via gel-hydrothermal treatment

    SciTech Connect

    Huang, Yan; Xie, Gang; Chen, Sanping; Gao, Shengli

    2011-03-15

    Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} were prepared with the coordination compounds [M(S{sub 2}CNEt){sub 3}] (M=Sb, Bi; S{sub 2}CNEt=pyrrolidinedithiocarbamate) as precursors via gel-hydrothermal techniques. The doped TiO{sub 2} were characterized by XRD, SEM, XPS and UV-vis diffuse reflectance means. The photocatalyst based on doped TiO{sub 2} for photodecolorization of 4-nitrophenol (4-NP) was examined. The optimal Bi{sub 2}S{sub 3}/Sb{sub 2}S{sub 3} content, pH and different doped techniques have been investigated. Photocatalytic tests reveal that M{sub 2}S{sub 3} doped TiO{sub 2} via the gel-hydrothermal route performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol (4-NP). -- Graphical abstract: Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} were prepared using [M(S{sub 2}COEt){sub 3}] (M=Sb, Bi; S{sub 2}COEt=pyrrdidine-1-dithiocarbamaate) as precursors via gel-hydrothermal techniques. M{sub 2}S{sub 3} doped TiO{sub 2} performs better photocatalytic activity for photodegradation reaction of 4-nitrophenol. Display Omitted Highlights: {yields} The coordination compounds [M(S{sub 2}CNEt){sub 3}] (M=Sb, Bi; S{sub 2}CNEt=pyrrolidinedithiocarbamate) as precursors to prepare Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2}. {yields} The sol-hydrothermal, sol-gel and gel-hydrothermal processes for photocatalysis fabrication were employed and compared. {yields} Sb{sub 2}S{sub 3}/Bi{sub 2}S{sub 3} doped TiO{sub 2} obtained via the gel-hydrothermal process showed better performance for photodecolorization test of 4-nitrophenol (4-NP).

  20. The detection of genomic DNA from bacterial cells using iron oxide nanoparticles synthesized by a hydrothermal process

    NASA Astrophysics Data System (ADS)

    Kim, Young-Sung; Kim, Ki-Chul; Hong, Tae-Whan

    2010-04-01

    We used iron oxide nanoparticles in order to extract purified DNA from bacterial cells. Magnetite (Fe3O4) and maghemite (γ-Fe2O3) are synthesized with FeSO4·7H2O via a hydrothermal process and used as a medium to detect DNA. Various characterizations were performed including X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy, vibrating sample magnetometry, and Mössbauer spectroscopy. According to the XRD results, the XRD peaks of the synthesized magnetite and maghemite nanoparticles corresponded well with JCPDS standard data, respectively. The particle size of the iron oxide nanoparticles was about 20 nm, and the particle shape was almost spherical, which was confirmed by observation of the HRTEM image. The magnetite nanoparticles have a face-centeredcubic inverse spinel structure with a space group Fd bar 3 m, as confirmed by HRTEM and Mössbauer spectroscopy analyses. An agarose gel eletrophoresis analysis was performed to confirm the extraction ability of DNA using these iron oxide nanoparticles, revealing stronger reaction of the maghemite nanoparticles than the magnetite nanoparticles.

  1. Extreme Hydrothermal Conditions Near an Active Geological Fault, DFDP-2B Borehole, Alpine Fault, New Zealand

    NASA Astrophysics Data System (ADS)

    Sutherland, R.; Townend, J.; Toy, V.; Allen, M.; Baratin, L. M.; Barth, N. C.; Beacroft, L.; Benson, A.; Boese, C. M.; Boles, A.; Boulton, C. J.; Capova, L.; Carpenter, B. M.; Celerier, B. P.; Chamberlain, C. J.; Conze, R.; Cooper, A.; Coussens, J.; Coutts, A.; Cox, S.; Craw, L.; Doan, M. L.; Eccles, J. D.; Faulkner, D.; Grieve, J.; Grochowski, J.; Gulley, A.; Henry, G.; Howarth, J. D.; Jacobs, K. M.; Jeppson, T.; Kato, N.; Keys, S.; Kirilova, M.; Kometani, Y.; Lukács, A.; Langridge, R.; Lin, W.; Little, T.; Mallyon, D.; Mariani, E.; Marx, R.; Massiot, C.; Mathewson, L.; Melosh, B.; Menzies, C. D.; Moore, J.; Morales, L. F. G.; Morgan, C.; Mori, H.; Niemeijer, A. R.; Nishikawa, O.; Nitsch, O.; Paris Cavailhes, J.; Pooley, B.; Prior, D. J.; Pyne, A.; Sauer, K. M.; Savage, M. K.; Schleicher, A.; Schmitt, D. R.; Shigematsu, N.; Taylor-Offord, S.; Tobin, H. J.; Upton, P.; Valdez, R. D.; Weaver, K.; Wiersberg, T.; Williams, J. N.; Yeo, S.; Zimmer, M.; Broderick, N.

    2015-12-01

    The DFDP-2B borehole sampled rocks above and within the upper part of the Alpine Fault, New Zealand, to a depth of 893 m in late 2014. The experiment was the first to drill a major geological fault zone that is active and late in its earthquake cycle. We determined ambient fluid pressures 8-10% above hydrostatic and a geothermal gradient of 130-150 °C/km in rocks above the fault. These unusual ambient conditions can be explained by a combination of: rock advection that transports heat from depth by uplift and oblique slip on the fault; and fluid advection through fractured rock, driven by topographic forcing, which concentrates heat and causes fluid over-pressure in the valley. Highly-anomalous ambient conditions can exist in the vicinity of active faults, and earthquake and mineralization processes occur within these zones.

  2. Discovery of Nascent Vents and Recent Colonization Associated with(Re)activated Hydrothermal Vent Fields by the GALREX 2011 Expedition on the Galápagos Rift

    NASA Astrophysics Data System (ADS)

    Shank, T. M.; Holden, J. F.; Herrera, S.; Munro, C.; Muric, T.; Lin, J.; Stuart, L.

    2011-12-01

    GALREX 2011 was a NOAA OER telepresence cruise that explored the diverse habitats and geologic settings of the deep Galápagos region. The expedition made12 Little Hercules ROV dives in July 2011.Abundant corals and a strong depth zonation of species (including deepwater coral communities) were found near 500 m depth on Paramount Seamount, likely influenced by past low sea level states, wave-cut terrace processes, and the historical presence of shallow reef structures. At fresh lava flows with associated (flocculent) hydrothermal venting near 88° W, now known as Uka Pacha and Pegasus Vent Fields, rocks were coated with white microbial mat and lacked sessile fauna, with few mobile fauna (e.g., bythograeid crabs, alvinocarid shrimp, polynoid worms, zoarcid fish, and dirivultid copepods). This suggests a recent creation of hydrothermal habitats through volcanic eruptions and/or diking events, which may have taken place over a 15 km span separating the two vent fields. The Rosebud vent field at 86°W was not observed and may have been covered with lava since last visited in 2005. A hydrothermal vent field near 86°W was discovered that is one of the largest vent fields known on the Rift (120m by 40m). Low-temperature vent habitats were colonized by low numbers of tubeworms including Riftia, Oasisia, and a potential Tevnia species (the latter not previously observed on the Galapagos Rift). Patches of tubeworms were observed with individuals less than 2cm in length, and the relatively few large Riftia had tube lengths near 70cm long. Large numbers of small (< 3cm long) bathymodiolin mussels lined cracks and crevices throughout the active part of the field. Live clams, at least four species of gastropod limpets, three species of polynoid polychaetes, juvenile and adult alvinocarid shrimp, actinostolid anemones, and white microbial communities were observed on the underside and vertical surfaces of basalt rock surfaces. There were at least 13 species of vent-endemic fauna

  3. Solgel-hydrothermal synthesis of Tb/Tourmaline/TiO2 nano tubes and enhanced photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Huang, Fengping; Guo, Yuyu; Wang, Shuai; Zhang, Shuang; Cui, Mengli

    2017-02-01

    In this study, we synthesized Tb/Tourmaline/TiO2 nano tubes (NTs) through a solgel-hydrothermal method. The as-prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectromicroscope, scanning electron microscopy, transmission electron microscopy and UV-vis diffuse reflectance spectroscopy. The resulting Tb/Tourmaline/TiO2 NTs exhibited higher photocatalytic activity than pure TiO2 and TiO2 nano particles (NPs) in the degradation of menthyl orange under UV-light. Results revealed that doping rare earth element Tb could narrow the wide band gap of TiO2 and tourmaline could trap the photogenerated electron of TiO2 to inhibit the recombination of photogenerated electron-hole pairs.

  4. Quantification of diagenetic overprint processes deduced from fossil carbonate shells and laboratory-based hydrothermal alteration experiments

    NASA Astrophysics Data System (ADS)

    Griesshaber, Erika; Casella, Laura; Mavromatis, Vasileios; Dietzel, Martin; Immenhauser, Adrian; Schmahl, Wolfgang

    2016-04-01

    Benthic and nektonic marine biogenic carbonate archives represent the foundation of numerous studies aiming at reconstructions of past climate dynamics and environmental change. However, living organisms are not in thermodynamic equilibrium and create local chemical environments where physiologic processes such as biomineralization takes place. After the death of the organism the former physiologic disequilibrium conditions are not sustained any more and all biological tissues are altered by equilibration according to the surrounding environment: diagenesis. With increasing diagenetic alteration, the biogenic structure and fingerprint fades away and is replaced by inorganic features. Thus, recrystallization of organism-specific microstructure is a clear indicator for diagenetic overprint. Microstructural data, which mirror recrystallization, are of great value for interpreting geochemical proxies for paleo-environment reconstruction. Despite more than a century of research dealing with carbonate diagenesis, many of the controlling processes and factors are only understood in a qualitative manner. One of the main issues is that diagenetically altered carbonates are usually present as the product of a complex preceding diagenetic pathway with an unknown number of intermediate steps. In this contribution we present and discuss laboratory based alteration experiments with the aim to investigate time-series data sets in a controlled manner. We conducted hydrothermal alteration experiments with modern Arctica islandica (bivalvia) and Notosaria nigricans (brachiopoda) in order to mimic diagenetic overprint. We explore first the potential of electron backscattered diffraction (EBSD) measurements together with statistical data evaluation as a tool to quantify diagenetic alteration of carbonate skeletons. Subsequently, we compare microstructural patterns obtained from experimentally altered shell material with those of fossil specimens that have undergone variable degrees of

  5. Photocatalytic activity of Li-doped TiO{sub 2} nanoparticles: Synthesis via ionic liquid-assisted hydrothermal route

    SciTech Connect

    Ravishankar, T.N.; Nagaraju, G.; Dupont, Jairton

    2016-06-15

    Highlights: • TiO{sub 2}: Li nanoparticles were synthesized via an ionic liquid-assisted hydrothermal method. • The doping of Li to anatase TiO{sub 2} affects the properties of the resultant product. • TiO{sub 2}: Li nanoparticles were used as a photocatalyst for the degradation of dye. • TiO{sub 2}: Li nanoparticles were used as sensor, and antibacterial agent. • TiO{sub 2}: Li were used as reducing agent for the reduction of Cr{sup 6+} to Cr{sup 3+}. - Abstract: We have proposed a simple one pot synthesis of lithium-doped TiO{sub 2} nanoparticles (TiO{sub 2}:Li) via an ionic liquid-assisted hydrothermal method and their potential use as a photocatalyst for the degradation of organic dye, as well as the reduction of toxic Cr{sup 6+} to non toxic Cr{sup 3+}. The structure of TiO{sub 2}:Li nanoparticles was examined by XRD, FTIR, XPS, Raman, UV–vis, Photoluminescence spectroscopy and morphology by SEM and TEM. The incorporation of Li into anatase-phase TiO{sub 2} affected the optical properties of the resultant TiO{sub 2} nanoparticles. The photocatalytic activity of the TiO{sub 2}:Li nanoparticles was determined by degradation of trypan blue. Degradation studies showed improved photocatalytic activity of TiO{sub 2}:Li nanoparticles compared to TiO{sub 2} nanoparticles and bulk TiO{sub 2}. TiO{sub 2}:Li nanoparticles also functioned as a detoxification agent which was confirmed by the reduction of Cr{sup 6+} to Cr{sup 3+}.

  6. Formation of Ce 0.8Sm 0.2O 1.9 nanoparticles by urea-based low-temperature hydrothermal process

    NASA Astrophysics Data System (ADS)

    Cheng, Ming-Yao; Hwang, Ding-Han; Sheu, Hwo-Shuenn; Hwang, Bing-Joe

    The synthesis and formation mechanism of the nano-sized Ce 0.8Sm 0.2O 1.9 particles prepared by a urea-based low-temperature hydrothermal process was investigated in this study. From ex situ X-ray diffraction and induced coupled plasma-atomic emission spectroscopy investigations, it was found that large quantities of cerium hydroxide co-precipitated with some samarium hydroxide at the initial stage of the hydrothermal process. The remaining Sm 3+ ions in the solutions were further hydrolyzed and deposited on the surface of the cerium hydroxide-rich precipitates to form a core-shell-like structure. During the hydrothermal process, the core-shell-like structure transformed to a single cubic fluorite phase which is due to the incorporation of the deposited samarium hydroxide into the cerium oxide-rich core. Further, the average grain size of the synthesized nanocrystalline Ce 0.8Sm 0.2O 1.9 was reduced with increasing the urea concentration in the solution. The density of the disk prepared with the synthesized Ce 0.8Sm 0.2O 1.9 powders was found to increase with a decrease in the grain size of Ce 0.8Sm 0.2O 1.9. The existence of SO 4 2- anions in the SDC powders prepared at low-urea concentration may result in the SDC disks with low density due to their decomposition during sintering process.

  7. An in situ vapour phase hydrothermal surface doping approach for fabrication of high performance Co3O4 electrocatalysts with an exceptionally high S-doped active surface.

    PubMed

    Tan, Zhijin; Liu, Porun; Zhang, Haimin; Wang, Yun; Al-Mamun, Mohammad; Yang, Hua Gui; Wang, Dan; Tang, Zhiyong; Zhao, Huijun

    2015-04-04

    A facile in situ vapour phase hydrothermal (VPH) surface doping approach has been developed for fabrication of high performance S-doped Co3O4 electrocatalysts with an unprecedentedly high surface S content (>47%). The demonstrated VPH doping approach could be useful for enrichment of surface active sites for other metal oxide electrocatalysts.

  8. Microwave assisted hydrothermal synthesis of Ag/AgCl/WO{sub 3} photocatalyst and its photocatalytic activity under simulated solar light

    SciTech Connect

    Adhikari, Rajesh; Gyawali, Gobinda; Sekino, Tohru; Wohn Lee, Soo

    2013-01-15

    Simulated solar light responsive Ag/AgCl/WO{sub 3} composite photocatalyst was synthesized by microwave assisted hydrothermal process. The synthesized powders were characterized by X-Ray Diffraction (XRD) spectroscopy, X-Ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectroscopy (UV-Vis DRS), and BET surface area analyzer to investigate the crystal structure, morphology, chemical composition, optical properties and surface area of the composite photocatalyst. This photocatalyst exhibited higher photocatalytic activity for the degradation of rhodamine B under simulated solar light irradiation. Dye degradation efficiency of composite photocatalyst was found to be increased significantly as compared to that of the commercial WO{sub 3} nanopowder. Increase in photocatalytic activity of the photocatalyst was explained on the basis of surface plasmon resonance (SPR) effect caused by the silver nanoparticles present in the composite photocatalyst. Highlights: Black-Right-Pointing-Pointer Successful synthesis of Ag/AgCl/WO{sub 3} nanocomposite. Black-Right-Pointing-Pointer Photocatalytic experiment was performed under simulated solar light. Black-Right-Pointing-Pointer Nanocomposite photocatalyst was very active as compared to WO{sub 3} commercial powder. Black-Right-Pointing-Pointer SPR effect due to Ag nanoparticles enhanced the photocatalytic activity.

  9. Dye-adsorption capacity of high surface-area hydrogen titanate nanosheets processed via modified hydrothermal method.

    PubMed

    Padinhattayil, Hareesh; Augustine, Rimesh; Shukla, Satyajit

    2013-04-01

    High surface-area (380 m2 x g(-1)) hydrogen titanate nanosheets (HTNS) processed via the modified hydrothermal method have been utilized for the removal of methylene blue (MB) dye from an aqueous solution via the surface-adsorption process involving the electrostatic attraction mechanism. The HTNS have been characterized using the transmission electron microscope (TEM), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET) specific surface-area measurement techniques. The amount of MB dye adsorbed on the surface of HTNS at equilibrium (q(e)) has been examined as a function of contact time, initial dye-concentration, and initial solution-pH. Within the investigated range of initial solution-pH (2.5-11), the MB dye adsorption on the surface of HTNS has been observed to follow the pseudo-second-order kinetics with the dye-adsorption capacity of 119 mg x g(-1) at the initial solution-pH of - 10. The adsorption equilibrium follows the Langmuir isotherm within the initial solution-pH range of 2.5-10. However, in a highly basic solution (initial solution-pH -11), the adsorption equilibrium has been observed to follow the Langmuir, Freundlich, and Dubinin-Kaganer-Radushkevich (DKR) models in the different ranges of initial MB dye concentration. The mere dependence on the DKR model has not been observed within the investigated range of initial solution-pH. The differences in the dye-adsorption characteristics and capacity of HTNS, compared with those of hydrogen titanate nanotubes, have been attributed to the difference in their specific surface-area. Irrespective of the morphology, the maximum coverage of MB dye on the surface of hydrogen titanate has been noted to be the same (52%).

  10. Adsorption of crystal violet with diatomite earth&carbon by a modification of hydrothermal carbonization process.

    PubMed

    Zhang, Yanzhuo; Li, Jun; Chen, Guanghui; Bian, Wei; Lu, Yun; Li, Wenjing; Zheng, Zhaoming; Cheng, Xiaojie

    2016-01-01

    The high colority and difficulty of decolorization are the most important tasks on printing and dyeing wastewater. This study investigates the ability of diatomite earth&carbon (DE&C) as an adsorbent to removal crystal violet (CV) from aqueous solutions. Fourier transform infrared spectroscopy results indicate the importance of functional groups during the adsorption of CV. The obtained N2 adsorption-desorption isotherm values accord with well IUPAC type II. Our calculations determined a surface area of 73.15 m(2) g(-1) for DE&C and an average pore diameter of 10.56 nm. Equilibrium data of the adsorption process fitted very well to the Langmuir model (R(2) > 0.99). The results of kinetics study showed that the pseudo-second-order model fitted to the experimental data well. The thermodynamic parameters were also evaluated. ΔH° <0, ΔS° > 0 and ΔG° < 0 demonstrated that the adsorption process was spontaneous and exothermic for dye. Furthermore the positive value of ΔS° reflected good affinity of the CV dye.

  11. Geochemical and microbiological evidence for a hydrogen-based, hyperthermophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) beneath an active deep-sea hydrothermal field.

    PubMed

    Takai, Ken; Gamo, Toshitaka; Tsunogai, Urumu; Nakayama, Noriko; Hirayama, Hisako; Nealson, Kenneth H; Horikoshi, Koki

    2004-08-01

    Subsurface microbial communities supported by geologically and abiologically derived hydrogen and carbon dioxide from the Earth's interior are of great interest, not only with regard to the nature of primitive life on Earth, but as potential analogs for extraterrestrial life. Here, for the first time, we present geochemical and microbiological evidence pointing to the existence of hyperthermophilic subsurface lithoautotrophic microbial ecosystem (HyperSLiME) dominated by hyperthermophilic methanogens beneath an active deep-sea hydrothermal field in the Central Indian Ridge. Geochemical and isotopic analyses of gaseous components in the hydrothermal fluids revealed heterogeneity of both concentration and carbon isotopic compositions of methane between the main hydrothermal vent (0.08 mM and -13.8 per thousand PDB, respectively) and the adjacent divergent vent site (0.2 mM and -18.5 per thousand PDB, respectively), representing potential subsurface microbial methanogenesis, at least in the divergent vent emitting more 13C-depleted methane. Extremely high abundance of magmatic energy sources such as hydrogen (2.5 mM) in the fluids also encourages a hydrogen-based, lithoautotrophic microbial activity. Both cultivation and cultivation-independent molecular analyses suggested the predominance of Methanococcales members in the superheated hydrothermal emissions and chimney interiors along with the other major microbial components of Thermococcales members. These results imply that a HyperSLiME, consisting of methanogens and fermenters, occurs in this tectonically active subsurface zone, strongly supporting the existence of hydrogen-driven subsurface microbial communities.

  12. MoMar-Demo at Lucky Strike. A near-real time multidisciplinary observatory of hydrothermal processes and ecosystems at the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Cannat, M.; Sarradin, P.; Blandin, J.; Escartin, J.; Colaco, A.; MoMAR-Demo Scientific Party : Aron Michael, Aumont Virginie, Baillard Christian, Ballu Valérie, Barreyre Thibaut, Blandin Jérôme, Blin Alexandre, Boulart Cédric, Cannat Mathilde, Carval Thierry, Castillo Alain, Chavagnac Valérie, Coail Jean Yves, Colaço Ana, Corela Carlos, Courrier Christophe, Crawford Wayne, Cuvelier Daphné, Daniel Romuald, Dausse Denis, Escartin Javier, Fabrice Fontaine, Gabsi Taoufik, Gayet Nicolas, Guyader Gérard, Lallier François, Lecomte Benoit, Legrand Julien, Lino Silva, Miranda Miguel, Mitard Emmelyne, Pichavant Pascal, Pot Olivier, Reverdin Gilles, Rommevaux Céline, Sarradin Pierre Marie, Sarrazin Jozée, Tanguy Virginie, Villinger Heinrich, Zbinden Magali

    2011-12-01

    The MoMAR "Monitoring the Mid-Atlantic Ridge" project was initiated by InterRidge in 1998 to study the environmental instability resulting from active mid-ocean-ridge processes at hydrothermal vent fields south of the Azores. It then developped into a component of the ESONET (European Seafloor Observatory Network) and EMSO (European Multidisciplinary Subsea Observatory) programs, which coordinate eulerian observatory initiatives in the seas around Europe. MoMAR experiments have started in 2006 and address two main questions : What are the feedbacks between volcanism, deformation, seismicity, and hydrothermalism at a slow spreading mid-ocean ridge? and How does the hydrothermal ecosystem couple with these sub-seabed processes? The MoMAR-Demo project started in 2010 with partial support from ESONET. It has been implemented so far by 2 cruises of the RV Pourquoi Pas ? during which we successfully deployed (in 2010), and upgraded (in 2011) a near-realtime buoyed observatory system. The system comprises two Sea Monitoring Nodes (SeaMoN) at the seafloor, which are acoustically linked to a surface relay buoy (BoRel), ensuring satellite communication to a land base station in Brest (France). One SeaMoN node connects to a 3-components seismometer and an hydrophone for seismic event detection, and two pressure probes for geodetic measurements, and the other SeaMoN node connects to a video camera, a dissolved-iron analyzer, and an optode (oxygen and temperature probe) for ecological time studies. The BOREL transmission buoy is equiped with GPS (geodetic experiment and buoy location) and meteo station. Data and/or status signals from these sensors are transmitted every 6 hours, and put on line in compliance with the ESONET-EMSO data policy (temporary access through http://www.ifremer.fr/WC2en/allEulerianNetworks). The MoMAR-Demo system also allows for interactive connections and changes of data transmission rates on demand. It is nested in arrays of autonomous sensors (OBSs

  13. Hydrothermal Processing of Base Camp Solid Wastes To Allow Onsite Recycling

    DTIC Science & Technology

    2008-09-01

    Textiles Medical Waste Rubber Miscellaneous 295 9.3 143 10 11 349 179 4,151 328 51 70 47 39 40 25 13 3.9 5.3 134 4.2 65 4.7 4.8...7.8 11.3 Metals 0.4 8 Paper 9.1 35.2 Wood 72.8 5.8 Food waste 6.6 11.7 Yard waste 0.7 12.1 Glass 0.7 5.3 Rubber and textiles 0.5 7.4 WWTP Sludge...discrete droplets on the surface of the processed wood particles. Because lignin is naturally adhesive, it was thought that the lignin droplets would

  14. Recovery of algal oil from marine green macro-algae Enteromorpha intestinalis by acidic-hydrothermal process.

    PubMed

    Jeong, Gwi-Taek; Hong, Yong-Ki; Lee, Hyung-Ho; Kong, In-Soo; Kim, Joong Kyun; Park, Nam Gyu; Kim, Sung-Koo; Park, Don-Hee

    2014-09-01

    In this study, the recovery of algal oil from Enteromorpha intestinalis based on an acidic-hydrothermal reaction was investigated. Overall, the algal oil yield after the acidic-hydrothermal reaction was increased under the conditions of high reaction temperature, high catalyst concentration, and long reaction time within the tested ranges. Significantly, catalyst concentration, compared with reaction temperature and time, less affected algal oil recovery. The optimal acidic-hydrothermal reaction conditions for production of algal oil from E. intestinalis were as follows-200 °C reaction temperature, 2.92 % catalyst concentration, 54 min reaction time. Under these conditions, an 18.6 % algal oil yield was obtained. By increasing the combined severity factor, the algae oil recovery yield linearly increased.

  15. Synthesis of copper-core/carbon-sheath nanocables by a surfactant-assisted hydrothermal reduction/carbonization process.

    PubMed

    Deng, Bin; Xu, An-Wu; Chen, Guang-Yi; Song, Rui-Qi; Chen, Liuping

    2006-06-22

    A simple hydrothermal method has been developed for the one-step synthesis of copper-core/carbon-sheath nanocables in solution. The obtained nanostructures were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and high-resolution TEM (HRTEM), Raman, and UV-vis spectrum analysis. These copper@carbon nanocables formed through the hydrothermal reduction/carbonization in the presence of surfactant cetyltrimethylammonium bromide (CTAB) acting as the structure-directing agent by hydrothermal treatment. HRTEM and selected-area electron diffraction (SAED) indicate that the resulted Cu nanowires had the preferred [110] growth direction. The influence of the reaction temperature, reaction time, and pH on the final products was investigated in detail. The possible formation mechanism for copper-core/carbon-sheath nanocables was also proposed. Amorphous carbon nanotubes can be obtained by etching the copper core in the nanocables.

  16. Hydrothermal ore-forming processes in the light of studies in rock- buffered systems: II. Some general geologic applications

    USGS Publications Warehouse

    Hemley, J.J.; Hunt, J.P.

    1992-01-01

    The experimental metal solubilities for rock-buffered hydrothermal systems provide important insights into the acquisition, transport, and deposition of metals in real hydrothermal systems that produced base metal ore deposits. Water-rock reactions that determine pH, together with total chloride and changes in temperature and fluid pressure, play significant roles in controlling the solubility of metals and determining where metals are fixed to form ore deposits. Deposition of metals in hydrothermal systems occurs where changes such as cooling, pH increase due to rock alteration, boiling, or fluid mixing cause the aqueous metal concentration to exceed saturation. Metal zoning results from deposition occurring at successive saturation surfaces. Zoning is not a reflection simply of relative solubility but of the manner of intersection of transport concentration paths with those surfaces. Saturation surfaces will tend to migrate outward and inward in prograde and retrograde time, respectively, controlled by either temperature or chemical variables. -from Authors

  17. Hydrothermal Synthesis g-C3N4/Nano-InVO4 Nanocomposites and Enhanced Photocatalytic Activity for Hydrogen Production under Visible Light Irradiation.

    PubMed

    Hu, Bo; Cai, Fanpeng; Chen, Tianjun; Fan, Mingshan; Song, Chengjie; Yan, Xu; Shi, Weidong

    2015-08-26

    We synthesized g-C3N4/nano-InVO4 heterojunction-type photocatalyts by in situ growth of InVO4 nanoparticles onto the surface of g-C3N4 sheets via a hydrothermal process. The results of SEM and TEM showed that the obtained InVO4 nanoparticles 20 nm in size dispersed uniformly on the surface of g-C3N4 sheets, which revealed that g-C3N4 sheets was probably a promising support for in situ growth of nanosize materials. The achieved intimate interface promoted the charge transfer and inhibited the recombination rate of photogenerated electron-hole pairs, which significantly improved the photocatalytic activity. A possible growth process of g-C3N4/nano-InVO4 nanocomposites was proposed based on different mass fraction of g-C3N4 content. The obtained g-C3N4/nano-InVO4 nanocomposites could achieve effective separation of charge-hole pairs and stronger reducing power, which caused enhanced H2 evolution from water-splitting compared with bare g-C3N4 sheets and g-C3N4/micro-InVO4 composites, respectively. As a result, the g-C3N4/nano-InVO4 nanocomposite with a mass ratio of 80:20 possessed the maximum photocatalytic activity for hydrogen production under visible-light irradiation.

  18. Cavitational hydrothermal oxidation: A new remediation process. 1998 annual progress report

    SciTech Connect

    Suslick, K.S.

    1998-06-01

    'The primary goal is to develop a quantitative understanding of cavitation phenomena in aqueous media and the development of applications of cavitation to remediation processes. Efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions. This report summarizes work after one year of a three year project. In order to gain further understanding of the conditions present during cavitation, the author has continued his studies of sonoluminescence. He has made recent breakthroughs in the use of emission spectroscopy for temperature and pressure measurement of cavitation events, which he expects to publish shortly. He has been able to measure for the first time the temperature of cavitation in water during multi-bubble cavitation in the presence of aromatic hydrocarbons. The emission from excited states of C{sub 2} in water gives temperatures that are consistent with adiabatic compressional heating, with maximum temperatures of 4,300 K. Prior measurements of cavitation temperatures in low vapor pressure nonaqueous media gave somewhat higher temperatures of 5,000 K. This work lays permanently to rest exotic mechanisms for cavitational chemistry, at least for cavitation fields.'

  19. Cavitational hydrothermal oxidation: A new remediation process. Annual progress report, September 1996--August 1997

    SciTech Connect

    Suslick, K.S.

    1997-11-21

    'During the past year, the authors have continued to make substantial scientific progress on the understanding of cavitation phenomena in aqueous media and applications of cavitation to remediation processes. The efforts have focused on three separate areas: sonoluminescence as a probe of conditions created during cavitational collapse in aqueous media, the use of cavitation for remediation of contaminated water, and an addition of the use of ultrasound in the synthesis of novel heterogeneous catalysts for hydrodehalogenation of halocarbons under mild conditions. In order to gain further understanding of the conditions present during cavitation, the author has continued his studies of sonoluminescence. He has made recent breakthroughs in the use of emission spectroscopy for temperature and pressure measurement of cavitation events, which he expects to publish shortly. He has been able to measure for the first time the temperature of cavitation in water during multi-bubble cavitation in the presence of aromatic hydrocarbons. The emission from excited states of C{sub 2} in water gives temperatures that are consistent with adiabatic compressional heating, with maximum temperatures of 4,300 K. Prior measurements of cavitation temperatures in low vapor pressure nonaqueous media gave somewhat higher temperatures of 5,000 K. This work lays permanently to rest exotic mechanisms for cavitational chemistry, at least for cavitation fields.'

  20. High Temperature Hydrothermal Components in the Sediment Cover of the Saldanha Hydrothermal Field

    NASA Astrophysics Data System (ADS)

    Dias, A.; Frueh-Green, G. L.; Bernasconi, S. M.; Mills, R. A.; Taylor, R. N.; Barriga, F. J.

    2006-12-01

    The Saldanha hydrothermal field is located at a non-transform offset (NTO5), between the FAMOUS and AMAR segments on the Mid-Atlantic Ridge (N36° 34'; W33° 26'). This field was discovered in 1998 during the Saldanha cruise (FCT, Portugal and IFREMER, France) and was revisited in 2001 during the Seahma cruise (FCT, Portugal) and in 2004 during the CD167 cruise (NOC, UK and FCT, Portugal). It is a serpentinite-hosted hydrothermal field and in situ observations revealed that hydrothermal vents are scarce and disseminated along the ocean floor over an area of approximately 400m2. Weakly venting fluids discharge through centimeter-sized orifices. Maximum fluid temperatures of 9° C were measured with the Victor ROV in 2001. Surface sediments have been collected from the Saldanha hydrothermal field in 1998, 2001 and 2004 and differences concerning mineralogy and geochemistry were recorded between these sediments. Mineralogy, whole sediment geochemistry and isotope ((δ 13C, δ 18O, Pb and Nd) data suggest geochemical variations in hydrothermal activity in this system. Hydrothermal activity is more strongly recorded in sediments collected in 2004, which are richer in sulfide mineralization and in hydrothermally- derived elements such as Cu, Zn, Fe, Co, Ni and S. In these sediments, rare earth elements (REE) patterns are characteristically derived from vent fluids, with enrichment in light REE and a pronounced positive Eu anomaly. The seawater-derived REE components in these sediments are low, as revealed by a small negative Ce anomaly. Lead isotopic ratios are typically less radiogenic in the youngest sediments when compared with the ones recorded in 1998 and 2001 sediments, demonstrating a negligible contribution of Pb from pelagic sediments. This is in agreement with neodymium isotope analyses indicating a smaller seawater contribution in the 2004 sediments. Oxygen isotope compositions (δ18OSMOW=6,59-11,63‰) of hydrothermal calcites present throughout the 2004

  1. Older Hydrothermal Activity along the Northern Yellowstone Caldera Margin at Sulphur Creek, Yellowstone Park, Wyoming

    NASA Astrophysics Data System (ADS)

    Manion, J. L.; Larson, P.

    2008-12-01

    The Tuff of Sulphur Creek (480 ka) is well exposed in the Seven Mile Hole area of the Grand Canyon of the Yellowstone River, Yellowstone National Park, Wyoming. The rhyolitic tuff erupted after the collapse of the Yellowstone Caldera (640 ka) and hosts more than 350 vertical meters of hydrothermal alteration. Two epithermal alteration assemblages with different mineral associations have been identified in the area: an illite-silica-pyrite phase and a kaolinite-alunite-silica-pyrite phase. Kaolinite and opal occur along the canyon rim, montmorillonite and other smectites are found at intermediate depths, and illite and sulfides (pyrite) are found deepest in the section. Our work on the north side of the Sevenmile Hole altered area has found a complex system of veining. The veins are concentrated in the eastern portion of the canyon and are less frequent to the west. Brecciated cross-cutting veins ranging from 2 to 30cm wide are found at the base of the canyon. Moving vertically up the canyons walls, the veining style becomes less complex. These veins are about 1 to 1.5cm wide and are not brecciated, occurring less frequently than the brecciated veins. The canyon walls and the canyon rim mainly contain millimeter-scale cross-cutting silica veinlets. These stockwork-like veinlets are the most abundant fracture filling that we find throughout the canyon walls. Veins at the base of the system, found in the stream bed, contain abundant sulfides (mainly pyrite). Sulfides are present in three forms: disseminated in a silica matrix, as massive pyrite in healed fractures, and encrusting clays and silica. The latter is the least common. Disseminated and massive sulfides are typically associated with the matrix in the brecciated veins. Breccias include angular clasts of altered tuff with argillized feldspar phenocrysts and fragments of earlier vein-filling opal. Sulfides are most abundant in the bottom of the canyon and in the western part of the field area. Hydrothermal

  2. Production of xylitol and tetrahydrofurfuryl alcohol from xylan in napier grass by a hydrothermal process with phosphorus oxoacids followed by aqueous phase hydrogenation.

    PubMed

    Takata, Eri; Tsuruoka, Tatsushi; Tsutsumi, Ken; Tsutsumi, Yuji; Tabata, Kenji

    2014-09-01

    The production of xylitol and tetrahydrofurfuryl alcohol (THFA) from napier grass was studied using two steps: a hydrothermal process with phosphorus oxoacids followed by aqueous phase hydrogenation with Pd/C. Xylose obtained from the napier grass by the hydrothermal treatment with 3.0 wt% phosphorous acid was subsequently converted into xylitol at 51.6% yield of the xylan in napier grass by hydrogenation with 5.0 wt% Pd/C. The furfural produced from napier grass with a 3.0 wt% phosphoric acid treatment was also directly subjected to the hydrogenation as a hydrolysate to yield 41.4% THFA based on the xylan in napier grass. The yields of xylitol and THFA obtained by hydrogenation using the napier grass hydrolysate containing xylose or furfural were almost the same as those of hydrogenation using commercial materials. To our knowledge, this is the first report on the production of THFA in high yield by hydrogenation directly from biomass hydrolysate.

  3. Crater lake and post-eruption hydrothermal activity, El Chichón Volcano, Mexico

    USGS Publications Warehouse

    Casadevall, Thomas J.; de la Cruz-Reyna, Servando; Rose, William I.; Bagley, Susan; Finnegan, David L.; Zoller, William H.

    1984-01-01

    Explosive eruptions of Volcán El Chichón in Chiapas, Mexico on March 28 and April 3–4, 1982 removed 0.2 km3 of rock to form a 1-km-wide 300-m-deep summit crater. By late April 1982 a lake had begun to form on the crater floor, and by November 1982 it attained a maximum surface area of 1.4 × 105 m2 and a volume of 5 × 106 m3. Accumulation of 4–5 m of rainfall between July and October 1982 largely formed the lake. In January 1983, temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115°C; by October 1983 the maximum temperature of fumarole emissions was 99°C. In January 1983 fumarole gas emissions were greater than 99 vol. % H2O with traces of CO2, SO2, and H2S. The water of the lake was a hot (T = 52–58°C), acidic (pH = 0.5), dilute solution (34,046 mg L−1 dissolved solids; Cl/S = 20.5). Sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits, together with less than 1% of elemental sulfur. The composition and temperature of the lake water is attributed to: (1) solution of fumarole emissions; (2) reaction of lake water with hot rocks beneath the lake level; (3) sediments washed into the lake from the crater walls; (4) hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement; (5) evaporation; and (6) precipitation.

  4. Elucidating some issues regarding the synthesis of superparamagnetic-like single crystalline micrometric Fe3O4 during the hydrothermal process

    NASA Astrophysics Data System (ADS)

    Kiss, Mihaela Luminita; Chirita, Marius; Mihaila, Alexandru Ionut Chirita; Beljung, Corina Ana; Niznansky, Daniel; Savii, Cecilia

    2015-12-01

    By hydrothermal decomposition of the Fe-EDTA complex, at 230°C, after 38 h of high -pressure treatment time, magnetite octahedrons with micrometric dimensions (15-45 µm) were obtained. Unusual and notable for these crystallites is the very small hysteresis surface, indicating a superparamagnetic-like behavior at micrometer scale, which means that the agglomeration of these crystallites is avoided after the removal of the magnetic field. This behavior can be correlated with a low level of imperfections in magnetite octahedrons, involving a low level of internal stresses, which leads to coercivity decreasing. The large dispersion in the crystallite axes is consistent with low remanence. We assumed that these attributes are related to the hydrothermal crystal growth process. To elucidate some issues regarding the magnetite crystallites development during the hydrothermal process, a careful observation of occurring intermediate phases by optical and SEM microscopy has been performed. Also the purity of the ferrous carbonate/magnetite mixture was analyzed by FTIR and Mössbauer spectroscopy

  5. Hydrothermal activity on the eastern SWIR (50°-70°E): Evidence from core-top geochemistry, 1887 and 1998

    NASA Astrophysics Data System (ADS)

    German, Christopher R.

    Evidence for hydrothermal activity on the eastern SWIR has been reported previously in the form of optical-backscatter anomalies interpreted to indicate the presence of hydrothermal plumes. Here, I report on a brief reconnaissance analysis of the geochemical composition of core-top samples collected from sites both beneath and away from those previously-reported plume signals to determine whether evidence for fall-out of hydrothermal plume material is discernible. Samples used for this study were collected using the deep-diving submersible SHINKAI 6500 in 1998 and from the tallow-coatings applied to lead sounding lines, 111 years earlier, aboard HMS Egeria. The data indicate hydrothermal input to all but one of eight SHINKAI 6500 cores along the length of the eastern SWIR rift-valley, including the site of strongest previously reported plume anomalies. Comparison with a recent MAR study suggests that the cores analyzed here, however, may predominantly lie distant from any current or recently-active source of venting.

  6. Hydrothermal activity on the eastern SWIR (50°-70°E): Evidence from core-top geochemistry, 1887 and 1998

    NASA Astrophysics Data System (ADS)

    German, Christopher R.

    2003-07-01

    Evidence for hydrothermal activity on the eastern SWIR has been reported previously in the form of optical-backscatter anomalies interpreted to indicate the presence of hydrothermal plumes. Here, I report on a brief reconnaissance analysis of the geochemical composition of core-top samples collected from sites both beneath and away from those previously-reported plume signals to determine whether evidence for fall-out of hydrothermal plume material is discernible. Samples used for this study were collected using the deep-diving submersible SHINKAI 6500 in 1998 and from the tallow-coatings applied to lead sounding lines, 111 years earlier, aboard HMS Egeria. The data indicate hydrothermal input to all but one of eight SHINKAI 6500 cores along the length of the eastern SWIR rift-valley, including the site of strongest previously reported plume anomalies. Comparison with a recent MAR study suggests that the cores analyzed here, however, may predominantly lie distant from any current or recently-active source of venting.

  7. Comparative study of photocatalytic activities of hydrothermally grown ZnO nanorod on Si(001) wafer and FTO glass substrates

    NASA Astrophysics Data System (ADS)

    Jeon, Eun Hee; Yang, Sena; Kim, Yeonwoo; Kim, Namdong; Shin, Hyun-Joon; Baik, Jaeyoon; Kim, Hyun Sung; Lee, Hangil

    2015-09-01

    ZnO nanorods have been grown on Si(001) wafer and fluorine-doped tin oxide (FTO) glass substrates for 1 and 4 h with the hydrothermal methods. The morphologies and photocatalytic activities of the ZnO nanorods were found to depend on the substrates. We investigated their properties by using spectroscopic analysis and demonstrated that the shape of nanorod and the ratios of external defects can be controlled by varying the substrates. Our experiments revealed that the nanorods grown on Si(001) have a single-crystalline wurtzite structure with (002) facets and that the number of surface oxygen defects increases with their length as the growth time increases. The nanorods grown on Si(001) have different facets, in particular wider (002) facets, and a higher ratio of the oxygen defect than the nanorods on FTO glass substrate. Moreover, the photocatalytic activities with respect to 2-aminothiophenol (2-ATP) of these nanorods were investigated with high-resolution photoemission spectroscopy (HRPES). We demonstrated that their photocatalytic activity is influenced by the ratios of surface oxygen defects, which varies with the substrate surface.

  8. Hydrothermal Activity on the Southern Mid-Atlantic Ridge: Tectonically- and Volcanically-Hosted High Temperature Venting at 2-7 Degrees S

    NASA Astrophysics Data System (ADS)

    German, C. R.; Parson, L. M.; Murton, B. J.; Bennett, S. A.; Connelly, D. P.; Evans, A. J.; Prien, R. D.; Ramirez-Llodra, E. Z.; Shank, T. M.; Yoerger, D. R.; Jakuba, M.; Bradley, A. M.; Baker, E. T.; Nakamura, K.

    2005-12-01

    We have conducted a systematic investigation for hydrothermal activity along the southern Mid-Atlantic Ridge, 2°30-6°50 S. Our initial approach was to use a combination of multi-beam swath mapping, deep-tow sidescan sonar imaging and water column plume-detection using MAPRs and CTD-rosette system to locate new sites of hydrothermal activity immediately south of the Romanche and Chain Fracture zones. We wanted to test whether these geologic features represent a significant barrier to gene-flow along-axis away from northern MAR vent ecosystems. During the first leg of our research cruise (RRS Charles Darwin cruise CD169, Feb-Mar 2005) we used this approach to identify two hydrothermally active regions, one in a non-transform discontinuity near 4°S and the other in a segment centre characterised by very fresh sheet-flows near 5°S. During Leg 2 we returned to the second of these areas and deployed ABE, WHOI's autonomous underwater vehicle, in a three-phase strategy to prospect for, locate, and image new hydrothermal fields. During Phase 1 two discrete target areas were located ca. 1km apart along strike within the segment centre. During Phase 2 these two areas were each mapped in detail using an SM2000 system while in situ optical back scatter, Eh, temperature, Mn and Fe(II) sensors were used to confirm the interception of buoyant hydrothermal plumes rising from the seafloor. Finally we redeployed ABE (Phase 3) to collect photo-mosaics of each of two new vent-areas whilst simultaneously sampling their buoyant plumes by CTD-rosette for TDMn, Fe and CH4 analyses.

  9. Galapagos rift at 86 /sup 0/W 5. Variations in volcanism, structure, and hydrothermal activity along a 30-kilometer segment of the rift valley

    SciTech Connect

    Ballard, R.D.; van Andel, T.H.; Holcomb, R.T.

    1982-02-10

    A 30-km segment of the Galapagos Rift near 86 /sup 0/W has been mapped in detail using the Angus towed camera system, the submersible Alvin, and multi-narrowbeam sonar data. Recent volcanic activity and active hydrothermal circulation are evident along the entire length of the segment mapped. There are, however, clear along-strike variations in these processes which render previous two-dimensional models obsolete. Although alternate explanations are possible, eruptive sequences appear to begin with the outpouring of surface-fed sheet flows and end with more channelized pillow flows. In the western portion of the rift studied, sheet flows dominate with the entire valley floor covered by recent flows associated with a broad shield volcano. The eastern portion, on the other hand, is narrower; consisting primarily of less voluminous pillow flows of apparently the same youthful age. Three possible models for the volcanic evolution of this rift segment are presented. According to the first model, the extrusive portion of the crust is formed by a distinct volcanic episode, followed by a long period of volcanic quiescence. The volcanic phase begins with voluminous sheet flows emerging from numerous eruptive fissures, which in time evolve into a narrow pillow ridge. Farther along-strike, where the flows are smaller and the extrusive zone narrow, the marginal portions undergo continued fissuring and subsequent uplift to form marginal highs and lows. This deformational activity also affects the extrusive zone once volcanic activity ends, converting the distinctly lobate topography of the active period into highly lineated fault-controlled terrain. According to the second model, extension and volcanism can be viewed as a continuous process without major periods of volcanic quiescence. The initial lava flows of a new eruptive sequence fill low areas, frequently spilling over local sills and flooding much of the rift valley.

  10. Preliminary results of trace elements mobility in soils and plants from the active hydrothermal area of Nisyros island (Greece)

    NASA Astrophysics Data System (ADS)

    Daskalopoulou, Kyriaki; Calabrese, Sergio; Milazzo, Silvia; Brusca, Lorenzo; D'Alessandro, Walter; Kyriakopoulos, Konstantinos; Tassi, Franco; Parello, Francesco

    2014-05-01

    Trace elements, i.e. chemical constituents of rocks with concentration <1000 ppm, play a structural role in the organisms and use proteins as a carrier to their target site. Their toxicity depends on their concentration, speciation and reactions with other elements. In volcanic environments, significant amounts of trace elements discharged from gas emissions, contribute to produce air particulate. Nisyros Island is a stratovolcano located at the South Aegean active Volcanic Arc. Intense hydrothermal activity characterise the Lakki caldera. In particular, the fumaroles located in the craters of Stefanos, Kaminakia, Lofos Dome and the area comprising Phlegeton, Polyvotes Micros and Polyvotes Megalos discharge hydrothermal fluids rich in H2O (91- 99%), SO2 and H2S. Their temperatures are almost 100o C and H2S is highly abundant accounting for 8-26 % of the released dry gas phase. On June 2013, during a multidisciplinary field trip on Nisyros island, 39 samples of top soils and 31 of endemic plants (Cistus Creticus and Salvifolius and Erica Arborea and Manipuliflora) were collected in the caldera area, with the aim to investigate the distribution of concentrations of trace elements related to the contribution of deep originated fluids. Moreover, one sample of plant and soil was collected outside the caldera as local background, for comparison. All the soil samples were powdered avoiding metal contamination and they were extracted twice, using HNO3 + HCl for one extraction (closed microwave digestion) and ultrapure de- ionized water for the other one (leaching extraction). The leaves of plants were gently isolated, dried and powdered for acid microwave extraction (HNO3 + H2O2). All the solutions were analysed for major and trace elements contents by using ionic chromatography (IC) and inductively plasma spectrometry (ICP-MS and ICP-OES). The preliminary results showed high enrichment of many trace elements both in plant and soils respect to the local background, in

  11. Cooked Volatiles and the Origin of Titan's Atmosphere: Evidence of Deep Hydrothermal Activity?

    NASA Astrophysics Data System (ADS)

    Glein, C. R.

    2014-12-01

    As on the terrestrial planets, key clues to the origin of Titan's enigmatic atmosphere are contained in the abundances of noble gases and stable isotopes in the atmosphere. The Huygens GCMS measured the abundances of 40Ar, 36Ar, and 22Ne (tentatively); as well as the nitrogen and carbon isotopic compositions of atmospheric N2 and CH4, respectively. No isotopes of Kr or Xe were detected (<10 ppbv). Cassini CIRS has provided us with the D/H ratio in CH4. Here, I attempt to explain these data by developing the hypothesis that the noble gases, nitrogen, and methane originated in the rocky core of Titan [1]. The presence of 40Ar demonstrates that volatile species can be delivered from the deep interior to the atmosphere. Consistent with [2], I find that Titan's primordial core should have contained sufficient 36Ar and 22Ne to explain their reported abundances. By extrapolating this model, I provide a new explanation for why the GCMS failed to detect Kr or Xe, as the predicted mixing ratios of 84Kr and 132Xe are ~0.2 ppbv and ~0.01 ppbv, respectively. I find that nitrogen should be outgassed similarly to argon, while krypton can serve as a geochemical proxy for methane, given the similar volatilities of these pairs of substances. This allows me to deduce that geochemical reactions in Titan's core could have generated enough N2 and CH4 from accreted NH3 and CO2, respectively. A hydrothermal origin of atmospheric nitrogen is also supported by the similarity in N isotopes between Titan's N2 and cometary NH3 [3]. I find that the isotopic ratios in methane can be explained by low-temperature (~300 K) equilibria with liquid water and the alteration mineral calcite. Looking toward the future, this model predicts 12C/13C ≈ 84 in dry ice, and D/H ≈ 170 ppm in water ice on Titan's surface. References: [1] Glein C.R. (2014) Icarus, submitted; [2] Tobie G., et al. (2012) ApJ 752, 125; [3] Mandt K.E., et al. (2014) ApJ Lett. 788, L24.

  12. Template-free synthesis of ZnWO{sub 4} powders via hydrothermal process in a wide pH range

    SciTech Connect

    Hojamberdiev, Mirabbos; Zhu, Gangqiang; Xu, Yunhua

    2010-12-15

    ZnWO{sub 4} powders with different morphologies were fabricated through a template-free hydrothermal method at 180 {sup o}C for 8 h in a wide pH range. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible and luminescence spectrophotometers were applied to study the effects of pH values on crystallinity, morphology, optical and luminescence properties. The XRD results showed that the WO{sub 3} + ZnWO{sub 4}, ZnWO{sub 4}, and ZnO phases could form after hydrothermal processing at 180 {sup o}C for 8 h with the pH values of 1, 3-11, and 13, respectively. The SEM and TEM observation revealed that the morphological transformation of ZnWO{sub 4} powders occurred with an increase in pH values as follows: star anise-, peony-, and desert rose-like microstructures and soya bean- and rod-like nanostructures. The highest luminescence intensity was found to be in sample consisting of star anise-like crystallites among all the samples due to the presence of larger particles with high crystallinity resulted from the favorable pH under the current hydrothermal conditions.

  13. Effect of reaction parameters on photoluminescence and photocatalytic activity of zinc sulfide nanosphere synthesized by hydrothermal route

    NASA Astrophysics Data System (ADS)

    Chanu, T. Inakhunbi; Samanta, Dhrubajyoti; Tiwari, Archana; Chatterjee, Somenath

    2017-01-01

    Zinc Sulfide (ZnS) nanospheres have been synthesized using amino acid, L-Histidine as a capping agent by hydrothermal method. The as prepared ZnS have been characterised using X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), High Resolution Transmission Electron Microscopy (HRTEM), Photoluminescence (PL), Fourier Transform Infra-Red spectroscopy (FTIR), UV-vis absorption spectroscopy and X-ray Photo Electron Spectroscopy (XPS). Effect of reaction parameters on particle size has been investigated. The morphology and size of the ZnS can be tuned based on the reaction parameters. ZnS nanosphere with a particle size of 5 nm is obtained when the reaction parameters are kept at 120 °C for 3 h. The PL of ZnS shows multiple defect emissions arising from interstitials/vacancies. Particle size of ZnS nanoparticles plays an important role in determining the photo catalytic activity. A chronological study on synthesis of ZnS nanosphere and its photo catalytic activity under the sunlight are discussed here, which reveals the photo degradation of Rhodamine B (RhB) upto 87% as observed with ZnS nanosphere having a particle size of 5 nm.

  14. Sodium dodecyl sulfate-assisted hydrothermal synthesis of mesoporous nickel cobaltite nanoparticles with enhanced catalytic activity for methanol electrooxidation

    NASA Astrophysics Data System (ADS)

    Ding, Rui; Qi, Li; Jia, Mingjun; Wang, Hongyu

    2014-04-01

    Mesoporous nickel cobaltite (NiCo2O4) nanoparticles have been synthesized via a facile hydrothermal strategy with the assistance of sodium dodecyl sulfate (SDS) soft template (ST). Their physicochemical properties have been characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectra (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS) and nitrogen sorption measurements. Their electrocatalytic performances have been examined by cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) tests. The obtained NiCo2O4 materials exhibit a typical nanoscale crystalline hexagonal morphology with specific surface area (SSA) and mesopore volume of 88.63 m2 g-1 and 0.298 cm3 g-1. Impressively, the SDS-assisted NiCo2O4 electrode shows a catalytic current density of 125 mA cm-2 and 72% retention for consecutive 1000 s at 0.6 V in 1 M KOH and 0.5 M CH3OH electrolytes towards methanol (CH3OH) electrooxidation, which is better than the one without SDS assistance. The pronounced electrocatalytic activity is largely ascribed to their higher surface intensities of Co and Ni species and superior mesoporous nanostructures, which provide the richer electroactive sites and faster electrochemical kinetics, leading to the enhanced electrocatalytic activity.

  15. Monitoring for volcano-hydrothermal activity using continuous gravity and local ground acceleration measurements: New deployments at Inferno Crater, Waimangu and White Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur; Fournier, Nico; Cole-Baker, Jeremy; Miller, Craig

    2010-05-01

    Volcanoes with crater lakes are often characterised by shallow hydrothermal systems which display cyclic behaviour (temperature, lake level, chemistry, etc.) and shallow seismic tremor. Present monitoring programmes in New Zealand include routine collection of these observables, but the associated shallow sub-surface processes are still inadequately modelled and poorly understood. Models would be better constrained with the incorporation of additional geophysical parameters. To this end, we have established a new test programme to continuously monitor for micro-gravity variations at New Zealand volcanoes. We utilise a Micro-g-LaCoste gPhone relative gravity meter having 1 Hz sample rate and a measurement precision of 1 microgal to test the viability of gravity monitoring for volcano-hydrothermal systems. We have initially tested the new sensor in a short term deployment (~2 months) at Inferno Crater, Waimangu, New Zealand. Inferno shows dramatic variations in crater lake level (> 7 m range), temperature (>40o C range) and hydrothermally derived tremor, all over a period of ~5 weeks. The amplitude and period of these observables are ideal for testing gravity variations associated with a cycling hydrothermal system because several cycles can be obtained in a relatively short campaign. We have deployed the gravity sensor into a buried vault having a stable concrete base to minimise local environmental influences. This vault is located ~20 meters from Inferno Lake edge (at high stand) and offers sufficient noise reduction to measure the gravitational effects associated with lake level changes. We will show results for the new gravity meter including raw relative gravity measurements and first order corrections (earth-tide, ocean loading, sensor level, temperature, and barometric pressure) to obtain both residual gravity and overprinted local ground accelerations (earthquakes and local tremor). To examine the effects of local ground vibrations on the gravity meter, we

  16. Multiple episodes of hydrothermal activity and epithermal mineralization in the southwestern Nevada volcanic field and their relations to magmatic activity, volcanism and regional extension

    SciTech Connect

    Weiss, S.I.; Noble, D.C.; Jackson, M.C.

    1994-12-31

    Volcanic rocks of middle Miocene age and underlying pre-Mesozoic sedimentary rocks host widely distributed zones of hydrothermal alteration and epithermal precious metal, fluorite and mercury deposits within and peripheral to major volcanic and intrusive centers of the southwestern Nevada volcanic field (SWNVF) in southern Nevada, near the southwestern margin of the Great Basin of the western United States. Radiometric ages indicate that episodes of hydrothermal activity mainly coincided with and closely followed major magmatic pulses during the development of the field and together spanned more than 4.5 m.y. Rocks of the SWNVF consist largely of rhyolitic ash-flow sheets and intercalated silicic lava domes, flows and near-vent pyroclastic deposits erupted between 15.2 and 10 Ma from vent areas in the vicinity of the Timber Mountain calderas, and between about 9.5 and 7 Ma from the outlying Black Mountain and Stonewall Mountain centers. Three magmatic stages can be recognized: the main magmatic stage, Mountain magmatic stage (11.7 to 10.0 Ma), and the late magmatic stage (9.4 to 7.5 Ma).

  17. Evidence of sub-vent biosphere: enzymatic activities in 308 °C deep-sea hydrothermal systems at Suiyo seamount, Izu Bonin Arc, Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Edazawa, Yae; Kobayashi, Kensei; Urabe, Tetsuro; Marumo, Katsumi

    2005-01-01

    A high-temperature deep-sea hydrothermal system related to dacitic arc-volcanism was drilled using a tethered, submarine rock-drill system as a part of the Archaean Park Project. The benthic multi-coring system (BMS) employed allowed for direct sampling of microorganisms, rocks and fluids beneath hydrothermal vents. The samples examined in this study were from sites APSK 05 and APSK 07 on the Suiyo Seamount of the Izu-Bonin Arc in the Pacific Ocean. Based on the vertical distribution of samples derived from this vigorous sub-vent environment, a model of deep-sea subterranean chemistry and biology was determined detailing optimal microbial activities. Deep-sea hydrothermal sub-vent core samples of dacitic arc-volcanism obtained at the Suiyo Seamount, Izu-Bonin Arc, Western Pacific Ocean were analyzed for acid and alkaline phosphatase enzymatic activities. Useful biomarkers of acid phosphatase (ACP) and alkaline phosphatase (ALP) enzymatic activities were positively correlated against each other and was greatest at the partial middle core sequences; ACP and ALP activities determined were as high as 5.10 and 6.80 nmol/min/g rock, respectively. Biochemical indicators of ACP and ALP were consistent with the origin of biogenic amino acids occupied in the sub-vent region and microbial cell number in the fluid. The significant enzymatic activities demonstrated in this study provides crucial evidence that sub-vent regions represent part of the previously unknown extreme-environment biosphere, extending the known subterranean habitable spaces of, for example, extremophilic microbes. This boring trial was first example of discharging high temperature hydrothermal activities at the frontal arc volcanoes.

  18. Activity of antioxidant enzymes in response to atmospheric pressure induced physiological stress in deep-sea hydrothermal vent mussel Bathymodiolus azoricus.

    PubMed

    Martins, Inês; Romão, Célia V; Goulart, Joana; Cerqueira, Teresa; Santos, Ricardo S; Bettencourt, Raul

    2016-03-01

    Deep sea hydrothermal Bathymodiolus azoricus mussels from Portuguese EEZ Menez Gwen hydrothermal field possess the remarkable ability to overcome decompression and survive successfully at atmospheric pressure conditions. We investigated the potential use of antioxidant defense enzymes in mussel B. azoricus as biomarkers of oxidative stress induced by long term acclimatization to atmospheric pressure conditions. Mussels collected at Menez Gwen hydrothermal field were acclimatized for two weeks in three distinct conditions suitable of promoting physiological stress, (i) in plain seawater for concomitant endosymbiont bacteria loss, (ii) in plain seawater under metal iron exposure, (iii) constant bubbling methane and pumped sulfide for endosymbiont bacteria survival. The enzymatic activities of superoxide dismutase (SOD), catalase (CAT), and iron storage proteins in addition to electrophoretic profiles were examined in vent mussel gills and digestive gland. Gills showed approximately 3 times more SOD specific activity than digestive glands. On the other hand, digestive glands showed approximately 6 times more CAT specific activity than gills. Iron storage proteins were identified in gill extracts from all experimental conditions mussels. However, in digestive gland extracts only fresh collected mussels and after 2 weeks in FeSO4 showed the presence of iron storage proteins. The differences between SOD, CAT specific activities and the presence of iron storage proteins in the examined tissues reflect dissimilar metabolic and antioxidant activities, as a result of tissue specificities and acclimatization conditions influences on the organism.

  19. The Timber Mountain magmato-thermal event: An intense widespread culmination of magmatic and hydrothermal activity at the southwestern Nevada volcanic field

    SciTech Connect

    Jackson, M.R. Jr.

    1988-05-01

    Eruption of the Rainier Mesa and Ammonia Tanks Members Timber Mountain Tuff at about 11.5 and 11.3 Ma, respectively, resulted in formation of the timber Mountain (TM) caldera; new K-Ar ages show that volcanism within and around the TM caldera continued for about 1 m.y. after collapse. Some TM age magmatic activity took place west and southeast of the TM caldera in the Beatty -- Bullfrog Hills and Shoshone Mountain areas, suggesting that volcanic activity at the TM caldera was an intense expression of an areally extensive magmatic system active from about 11.5 to 10Ma. Epithermal Au-Ag, Hg and fluorite mineralization and hydrothermal alteration are found in both within and surrounding the Timber Mountain -- Oasis Valley caldera complex. New K-Ar ages date this hydrothermal activity between about 13 and 10 Ma, largely between about 11.5 and 10 Ma, suggesting a genetic relation of hydrothermal activity to the TM magmatic system.

  20. The Lassen hydrothermal system

    USGS Publications Warehouse

    Ingebritsen, Steven E.; Bergfeld, Deborah; Clor, Laura; Evans, William C.

    2016-01-01

    The active Lassen hydrothermal system includes a central vapor-dominated zone or zones beneath the Lassen highlands underlain by ~240 °C high-chloride waters that discharge at lower elevations. It is the best-exposed and largest hydrothermal system in the Cascade Range, discharging 41 ± 10 kg/s of steam (~115 MW) and 23 ± 2 kg/s of high-chloride waters (~27 MW). The Lassen system accounts for a full 1/3 of the total high-temperature hydrothermal heat discharge in the U.S. Cascades (140/400 MW). Hydrothermal heat discharge of ~140 MW can be supported by crystallization and cooling of silicic magma at a rate of ~2400 km3/Ma, and the ongoing rates of heat and magmatic CO2 discharge are broadly consistent with a petrologic model for basalt-driven magmatic evolution. The clustering of observed seismicity at ~4–5 km depth may define zones of thermal cracking where the hydrothermal system mines heat from near-plastic rock. If so, the combined areal extent of the primary heat-transfer zones is ~5 km2, the average conductive heat flux over that area is >25 W/m2, and the conductive-boundary length <50 m. Observational records of hydrothermal discharge are likely too short to document long-term transients, whether they are intrinsic to the system or owe to various geologic events such as the eruption of Lassen Peak at 27 ka, deglaciation beginning ~18 ka, the eruptions of Chaos Crags at 1.1 ka, or the minor 1914–1917 eruption at the summit of Lassen Peak. However, there is a rich record of intermittent hydrothermal measurement over the past several decades and more-frequent measurement 2009–present. These data reveal sensitivity to climate and weather conditions, seasonal variability that owes to interaction with the shallow hydrologic system, and a transient 1.5- to twofold increase in high-chloride discharge in response to an earthquake swarm in mid-November 2014.

  1. Linking geology, fluid chemistry, and microbial activity of basalt- and ultramafic-hosted deep-sea hydrothermal vent environments.

    PubMed

    Perner, M; Hansen, M; Seifert, R; Strauss, H; Koschinsky, A; Petersen, S

    2013-07-01

    Hydrothermal fluids passing through basaltic rocks along mid-ocean ridges are known to be enriched in sulfide, while those circulating through ultramafic mantle rocks are typically elevated in hydrogen. Therefore, it has been estimated that the maximum energy in basalt-hosted systems is available through sulfide oxidation and in ultramafic-hosted systems through hydrogen oxidation. Furthermore, thermodynamic models suggest that the greatest biomass potential arises from sulfide oxidation in basalt-hosted and from hydrogen oxidation in ultramafic-hosted systems. We tested these predictions by measuring biological sulfide and hydrogen removal and subsequent autotrophic CO2 fixation in chemically distinct hydrothermal fluids from basalt-hosted and ultramafic-hosted vents. We found a large potential of microbial hydrogen oxidation in naturally hydrogen-rich (ultramafic-hosted) but also in naturally hydrogen-poor (basalt-hosted) hydrothermal fluids. Moreover, hydrogen oxidation-based primary production proved to be highly attractive under our incubation conditions regardless whether hydrothermal fluids from ultramafic-hosted or basalt-hosted sites were used. Site-specific hydrogen and sulfide availability alone did not appear to determine whether hydrogen or sulfide oxidation provides the energy for primary production by the free-living microbes in the tested hydrothermal fluids. This suggests that more complex features (e.g., a combination of oxygen, temperature, biological interactions) may play a role for determining which energy source is preferably used in chemically distinct hydrothermal vent biotopes.

  2. On the Interaction of a Vigorous Hydrothermal System with an Active Magma Chamber: The Puna Magma Chamber, Kilauea East Rift, Hawaii

    NASA Astrophysics Data System (ADS)

    Gregory, R. T.; Marsh, B. D.; Teplow, W.; Fournelle, J.

    2009-12-01

    The extent of the interaction between hydrothermal systems and active magma chambers has long been of fundamental interest to the development of ore deposits, cooling of magma chambers, and dehydration of the subducting lithosphere. As volatiles build up in the residual magma in the trailing edge of magmatic solidification fronts, is it possible that volatiles are transferred from the active magma to the hydrothermal system and vice versa? Does the external fracture front associated with vigorous hydrothermal systems sometimes propagate into the solidification front, facilitating volatile exchange? Or is the magma always sealed at temperatures above some critical level related to rock strength and overpressure? The degree of hydrothermal interaction in igneous systems is generally gauged in post mortem studies of δ18O and δD, where it has been assumed that a fracture front develops about the magma collapsing inward with cooling. H.P. Taylor and D. Norton's (1979; J. Petrol.)seminal work inferred that rocks are sealed with approach to the solidus and there is little to no direct interaction with external volatiles in the active magma. In active lava lakes a fracture front develops in response to thermal contraction of the newly formed rock once the temperature drops to ~950°C (Peck and Kinoshita,1976;USGS PP935A); rainfall driven hydrothermal systems flash to steam near the 100 °C isotherm in the solidified lake and have little effect on the cooling history (Peck et al., 1977; AJS). Lava lakes are fully degassed magmas and until the recent discovery of the Puna Magma Chamber (Teplow et al., 2008; AGU) no active magma was known at sufficiently great pressure to contain original volatiles. During the course of routine drilling of an injection well at the Puna Geothermal Venture (PGV) well-field, Big Island, Hawaii, a 75-meter interval of diorite containing brown glass inclusions was penetrated at a depth of 2415 m, continued drilling to 2488 m encountered a melt

  3. Active Inference: A Process Theory.

    PubMed

    Friston, Karl; FitzGerald, Thomas; Rigoli, Francesco; Schwartenbeck, Philipp; Pezzulo, Giovanni

    2017-01-01

    This article describes a process theory based on active inference and belief propagation. Starting from the premise that all neuronal processing (and action selection) can be explained by maximizing Bayesian model evidence-or minimizing variational free energy-we ask whether neuronal responses can be described as a gradient descent on variational free energy. Using a standard (Markov decision process) generative model, we derive the neuronal dynamics implicit in this description and reproduce a remarkable range of well-characterized neuronal phenomena. These include repetition suppression, mismatch negativity, violation responses, place-cell activity, phase precession, theta sequences, theta-gamma coupling, evidence accumulation, race-to-bound dynamics, and transfer of dopamine responses. Furthermore, the (approximately Bayes' optimal) behavior prescribed by these dynamics has a degree of face validity, providing a formal explanation for reward seeking, context learning, and epistemic foraging. Technically, the fact that a gradient descent appears to be a valid description of neuronal activity means that variational free energy is a Lyapunov function for neuronal dynamics, which therefore conform to Hamilton's principle of least action.

  4. The Biogeochemistry of Sulfur in Hydrothermal Systems

    NASA Technical Reports Server (NTRS)

    Schulte, Mitchell; Rogers, K. L.; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The incorporation of sulfur into many biomolecules likely dates back to the development of the earliest metabolic strategies. Sulfur is common in enzymes and co-enzymes and is an indispensable structural component in many peptides and proteins. Early metabolism may have been heavily influenced by the abundance of sulfide minerals in hydrothermal systems. The incorporation of sulfur into many biomolecules likely dates back to the development of the earliest metabolic strategies. Sulfur is common in enzymes and co-enzymes and is an indispensable structural component in many peptides and proteins. Early metabolism may have been heavily influenced by the abundance of sulfide minerals in hydrothermal systems. Understanding how sulfur became prevalent in biochemical processes and many biomolecules requires knowledge of the reaction properties of sulfur-bearing compounds. We have previously estimated thermodynamic data for thiols, the simplest organic sulfur compounds, at elevated temperatures and pressures. If life began in hydrothermal environments, it is especially important to understand reactions at elevated temperatures among sulfur-bearing compounds and other organic molecules essential for the origin and persistence of life. Here we examine reactions that may have formed amino acids with thiols as reaction intermediates in hypothetical early Earth hydrothermal environments. (There are two amino acids, cysteine and methionine, that contain sulfur.) Our calculations suggest that significant amounts of some amino acids were produced in early Earth hydrothermal fluids, given reasonable concentrations H2, NH3, H2S and CO. For example, preliminary results indicate that glycine activities as high as 1 mmol can be reached in these systems at 100 C. Alanine formation from propanethiol is also a favorable reaction. On the other hand, the calculated equilibrium log activities of cysteine and serine from propanethiol are -21 and -19, respectively, at 100 C. These results

  5. Implications of an ultramafic body in a basalt-dominated oceanic hydrothermal system on the vent fluid composition and on processes within sediments overlying a hydrothermal discharge zone: results of reactive-transport modeling

    NASA Astrophysics Data System (ADS)

    Alt-Epping, P.; Diamond, L. W.

    2009-04-01

    characterized by elevated H2(aq), SiO2(aq), H2S(aq) and a relatively low pH. If the discharge zone is covered by sediments, the infiltrating hydrothermal fluid mixes with the sediment pore-water and entrained seawater and the presence of H2(aq) initiates a series of redox processes such as the reduction of CO2 to CH4 and SO4-2 to H2S. Thus, mixing-induced redox processes involving H2 and SO4-2 provide a mechanism to form metal sulfides and potentially ore deposits. Furthermore, the presence of H2(aq) in the ascending fluid favors the stability of the low-sulfidation form of redox-sensitive minerals, such as pyrrhotite over pyrite. The sediments mark the transition zone that separates the hot, anoxic, low pH hydrothermal basement fluids from the cold, oxic, high pH seawater. Mixing between oxygenated seawater and/or the sediment porewater and the reduced, discharging H2, H2S and CH4-enriched hydrothermal fluid may provide conditions favorable for microbial chemosynthesis and an environment suitable for the growth of microorganisms. However, as the lherzolite becomes progressively altered the reactivity of its primary minerals decreases and hence the production of H2 declines. The decrease in reactivity of the ultramafic is enhanced by the hydrological sealing which is caused by the volume increase of the rock and by the corresponding porosity/permeability reduction associated with serpentinization. The decreasing H2 production changes the oxidation state of the discharging fluid and gradually leads to chemical fingerprints that are consistent with purely basaltic systems. Numerical studies of this type demonstrate that reactive transport simulations are useful in correlating observable changes in chemical parameters (i.e. the composition of the vent fluid or alteration of the sediment column overlying discharge zones) with processes that occur in regions of the system that are not easily accessible by direct seafloor exploration.

  6. Identification and characterization of the active hydrothermal deposits in Okinawa Trough, SW Japan: Estimates from logging-while-drilling

    NASA Astrophysics Data System (ADS)

    Saito, S.; Sanada, Y.; Moe, K.; Kido, Y. N.; Hamada, Y.; Kumagai, H.; Nozaki, T.; Takai, K.; Suzuki, K.

    2015-12-01

    A scientific drilling expedition was conducted at an active hydrothermal field on the Iheya-North Knoll by D/V Chikyu in 2014 (Expedition 907) as a part of "Next-generation Technology for Ocean Resources Survey" of the Cross-ministerial Strategic Innovation Promotion Program. During the expedition logging while drilling (LWD) was deployed to constrain the area of the fluid reservoir beneath seafloor followed by three coring holes down to 150 meter below the seafloor (mbsf). The LWD system is composed of arcVISION for resistivity and natural gamma ray measurement and TeleScope for real-time transmission of drilling parameters and arcVISION data. Five sites (C9011-15) at the Iheya-North Original Site and one site (C9016) at Aki Site were drilled with LWD. At C9012 and C9016, the arcVISION detected temperature anomaly up to 84℃ at 234 mbsf and up to 39℃ at 80 mbsf, respectively. The temperature quickly increases at that depth and it would reflect the existence of high-temperature heat source along borehole. Due to the continuous fluid circulation during drilling, the measured temperature does not indicate in-situ temperature, but it reflects the heat disturbed by the cold circulated water instead. High quality resistivity and natural gamma ray data were acquired at six sites. The log curves at Site C9016 show characteristic response; the natural gamma ray log exhibits extremely high radiation (>500 gAPI) at 7-13 and 23-31 mbsf (Zone A). In the underlying interval of 31-40 mbsf, the resistivity log exhibits extremely low value (<0.2 ohm-m) (Zone B). Then the resistivity log exhibits higher value (~10 ohm-m) and the natural gamma ray log shows very low radiation (<50 gAPI) at the interval of 41-48 mbsf (Zone C). The log characteristics in Zone A, B, and C can be interpreted as a series of K-rich alteration zone, sulfide zone, and low-K hard (silicified) sediments, respectively. The LWD-based lithological interpretation was confirmed by the following core description

  7. Hydrothermal synthesis of In2S3/g-C3N4 heterojunctions with enhanced photocatalytic activity.

    PubMed

    Xing, Chaosheng; Wu, Zhudong; Jiang, Deli; Chen, Min

    2014-11-01

    Graphitic carbon nitride (g-C3N4) was hybridized by In2S3 to form a novel In2S3/g-C3N4 heterojunction photocatalyst via a hydrothermal method. TEM and HRTEM results reveal that In2S3 nanoparticles and g-C3N4 closely contact with each other to form an intimate interface. The as-obtained In2S3/g-C3N4 heterojunctions exhibit higher photocatalytic activity than those of pure g-C3N4 and In2S3 for the photodegradation of rhodamine B (RhB) under visible light irradiation. The enhanced photocatalytic performance of In2S3/g-C3N4 heterojunctions could be attributed to its wide absorption in the visible region and efficient electron-hole separation. On the basis of radical scavenger experiments, superoxide radicals and holes are suggested to play a critical role in RhB degradation over In2S3/g-C3N4 heterojunctions.

  8. Detection of active hydrothermal vent fields in the Pescadero Basin and on the Alarcon Rise using AUV multibeam and CTD data

    NASA Astrophysics Data System (ADS)

    Caress, D. W.; Troni, G.; Clague, D. A.; Paduan, J. B.; Martin, J. F.; Thomas, H. J.; Thompson, D.; Conlin, D.; Martin, E. J.; meneses-Quiroz, E.; Nieves-Cardoso, C.; Angel Santa Rosa del Rio, M.

    2015-12-01

    The MBARI AUV D. Allan B. collected high resolution bathymetry, sidescan, and subbottom profiles along the neovolcanic zone of the Alarcon Rise and across the southern Pescadero Basin during 2012 and 2015 MBARI expeditions to the Gulf of California (GOC). The combination of high resolution multibeam bathymetry and seawater temperature data has proven effective in identifying active high temperature vent fields, as validated by inspection and sampling during ROV dives. The AUV carries a 200 kHz multibeam sonar, 110 kHz chirp sidescan sonar, a 1-6 kHz chirp subbottom profiler, and a conductivity, temperature and depth (CTD) sensor for ~17-hour duration missions. Flying at 5.4 km/hr at 50 m altitude, the processed AUV bathymetry has a 0.1 m vertical precision and a 1 m lateral resolution. Chimneys taller than 1.5 m are sufficiently distinctive to allow provisional identification. The CTD temperature data have a nominal 0.002°C accuracy. Following calculation of potential temperature and correcting for average local variation of potential temperature with depth, anomalies greater than 0.05 °C can be reliably identified using a spike detection filter. MBARI AUV mapping surveys are typically planned using a 150 m survey line spacing, so the CTD data may be collected as much as 75 m away from any vent plume source. Five active high temperature vent fields were discovered in the southern GOC, with the Auka Field in the southern Pescadero Basin, and the Ja Sít, Pericú, Meyibó, and Tzab-ek Fields along the Alarcon Rise. In all five cases, hydrothermal vent chimneys are readily identifiable in the multibeam bathymetry, and temperature anomalies are observed above background variability. Other apparent hydrothermal chimneys were observed in the bathmetry that did not exhibit water temperature anomalies; most of these were visited during ROV dives and confirmed to be inactive sites. The maximum water column anomalies are 0.13°C observed above the Meyibó field and 0.25

  9. The chemistry of hydrothermal magnetite: a review

    USGS Publications Warehouse

    Nadoll, Patrick; Angerer, Thomas; Mauk, Jeffrey L.; French, David; Walshe, John

    2014-01-01

    Magnetite (Fe3O4) is a well-recognized petrogenetic indicator and is a common accessory mineral in many ore deposits and their host rocks. Recent years have seen an increased interest in the use of hydrothermal magnetite for provenance studies and as a pathfinder for mineral exploration. A number of studies have investigated how specific formation conditions are reflected in the composition of the respective magnetite. Two fundamental questions underlie these efforts — (i) How can the composition of igneous and, more importantly, hydrothermal magnetite be used to discriminate mineralized areas from barren host rocks, and (ii) how can this assist exploration geologists to target ore deposits at greater and greater distances from the main mineralization? Similar to igneous magnetite, the most important factors that govern compositional variations in hydrothermal magnetite are (A) temperature, (B) fluid composition — element availability, (C) oxygen and sulfur fugacity, (D) silicate and sulfide activity, (E) host rock buffering, (F) re-equilibration processes, and (G) intrinsic crystallographic controls such as ionic radius and charge balance. We discuss how specific formation conditions are reflected in the composition of magnetite and review studies that investigate the chemistry of hydrothermal and igneous magnetite from various mineral deposits and their host rocks. Furthermore, we discuss the redox-related alteration of magnetite (martitization and mushketovitization) and mineral inclusions in magnetite and their effect on chemical analyses. Our database includes published and previously unpublished magnetite minor and trace element data for magnetite from (1) banded iron formations (BIF) and related high-grade iron ore deposits in Western Australia, India, and Brazil, (2) Ag–Pb–Zn veins of the Coeur d'Alene district, United States, (3) porphyry Cu–(Au)–(Mo) deposits and associated (4) calcic and magnesian skarn deposits in the southwestern United

  10. Visible light induced bactericidal and photocatalytic activity of hydrothermally synthesized BiVO4 nano-octahedrals.

    PubMed

    Sharma, Rishabh; Uma; Singh, Sonal; Verma, Ajit; Khanuja, Manika

    2016-09-01

    In the present work, monoclinic bismuth vanadate (m-BiVO4) nanostructures have been synthesized via simple hydrothermal method and employed for visible light driven antimicrobial and photocatalytic activity. Morphology (octahedral) and size (200-300nm) of the m-BiVO4 are studied using transmission electron microscopy (TEM). The crystal structure of m-BiVO4 (monoclinic scheelite structure) is confirmed by high resolution-TEM (HRTEM) and X-ray diffraction (XRD) studies. The band gap of m-BiVO4 was estimated to be ca. 2.42eV through Kubelka-Munk function F(R∞) using diffuse reflectance spectroscopy (DRS). Antimicrobial action of m-BiVO4 is anticipated by (i) shake flask method, (ii) MTT [3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide] assay for cytotoxicity. SEM analysis has been carried on Escherichia coli (E.coli) before and after treatment with nanostructure materials to reveal the mechanism underlying the antimicrobial action. Antimicrobial activity is studied as a function of m-BiVO4 concentration viz. 20, 40, 60 and 80ppm. The bacterial growth is decreased 80% to 96%, with the increase in m-BiVO4 concentration from 20ppm to 80ppm, respectively, in 2h. Photocatalytic activity and rate kinetics of m-BiVO4 nanostructures have been studied as a function of time on methylene blue (MB) dye degradation which is one of the waste products of textile industries and responsible for water pollution.

  11. Evidence for Hesperian Impact-Induced Hydrothermalism on Mars

    NASA Technical Reports Server (NTRS)

    Marzo, Giuseppe A.; Davila, Alfonso F.; Tornabene, Livio L.; Dohm, James M.; Fairen, Alberto G.; Gross, Christoph; Kneissl, Thomas; Bishop, Janice L.; Roush, Ted L.; McKay, Chris P.

    2010-01-01

    Several hydrated silicate deposits on Mars are observed within craters and are interpreted as excavated Noachian material. Toro crater (71.8 deg E, 17.0 deg N), located on the northern edge of the Syrtis Major Volcanic Plains, shows spectral and morphologic evidence of impact-induced hydrothermal activity. Spectroscopic observations were used to identify extensive hydrated silicate deposits, including prehnite, chlorites, smectites, and opaline material, a suite of phases that frequently results from hydrothermal alteration in terrestrial craters and also expected on Mars from geochemical modeling of hydrothermal environments. When combined with altimetry and high-resolution imaging data, these deposits appear associated predominantly with the central uplift and with portions of the northern part of the crater floor. Detailed geologic mapping of these deposits reveals geomorphic features that are consistent with hydrothermal activity that followed the impact event, including vent-like and conical mound structures, and a complex network of tectonic structures caused by fluid interactions such as fractures and joints. The crater age has been calculated from the cumulative crater size-frequency distributions and is found to be Early Hesperian. The evidence presented here provides support for impact-induced hydrothermal activity in Toro crater, that extends phyllosilicate formation processes beyond the Noachian era.

  12. Discovery of new hydrothermal activity and chemosynthetic fauna on the Central Indian Ridge at 18°-20° S.

    PubMed

    Nakamura, Kentaro; Watanabe, Hiromi; Miyazaki, Junichi; Takai, Ken; Kawagucci, Shinsuke; Noguchi, Takuro; Nemoto, Suguru; Watsuji, Tomo-o; Matsuzaki, Takuya; Shibuya, Takazo; Okamura, Kei; Mochizuki, Masashi; Orihashi, Yuji; Ura, Tamaki; Asada, Akira; Marie, Daniel; Koonjul, Meera; Singh, Manvendra; Beedessee, Girish; Bhikajee, Mitrasen; Tamaki, Kensaku

    2012-01-01

    Indian Ocean hydrothermal vents are believed to represent a novel biogeographic province, and are host to many novel genera and families of animals, potentially indigenous to Indian Ocean hydrothermal systems. In particular, since its discovery in 2001, much attention has been paid to a so-called 'scaly-foot' gastropod because of its unique iron-sulfide-coated dermal sclerites and the chemosynthetic symbioses in its various tissues. Despite increasing interest in the faunal assemblages at Indian Ocean hydrothermal vents, only two hydrothermal vent fields have been investigated in the Indian Ocean. Here we report two newly discovered hydrothermal vent fields, the Dodo and Solitaire fields, which are located in the Central Indian Ridge (CIR) segments 16 and 15, respectively. Chemosynthetic faunal communities at the Dodo field are emaciated in size and composition. In contrast, at the Solitaire field, we observed faunal communities that potentially contained almost all genera found at CIR hydrothermal environments to date, and even identified previously unreported taxa. Moreover, a new morphotype of 'scaly-foot' gastropod has been found at the Solitaire field. The newly discovered 'scaly-foot' gastropod has similar morphological and anatomical features to the previously reported type that inhabits the Kairei field, and both types of 'scaly-foot' gastropods genetically belong to the same species according to analyses of their COI gene and nuclear SSU rRNA gene sequences. However, the new morphotype completely lacks an iron-sulfide coating on the sclerites, which had been believed to be a novel feature restricted to 'scaly-foot' gastropods. Our new findings at the two newly discovered hydrothermal vent sites provide important insights into the biodiversity and biogeography of vent-endemic ecosystems in the Indian Ocean.

  13. In situ iron isotope ratio determination using UV-femtosecond laser ablation with application to hydrothermal ore formation processes

    NASA Astrophysics Data System (ADS)

    Horn, Ingo; von Blanckenburg, Friedhelm; Schoenberg, Ronny; Steinhoefel, Grit; Markl, Gregor

    2006-07-01

    The feasibility of in situ stable Fe isotope ratio measurements using UV-femtosecond laser ablation connected to a multiple-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) has been investigated. Different types of matrices, independently determined by solution MC-ICP-MS after chromatographic separation of Fe, have been analysed by laser ablation using the isotopically certified iron reference material IRMM-014 as the bracketing standard. The samples have been pure iron metal (JM Puratronic), Fe-meteorites (North Chile, Glenormiston and Toluca), the meteorite phases kamacite and taenite in Toluca and Fe-sulphides. Furthermore, Fe isotope ratios from hydrothermal hematite, siderite and goethite from an old mining area in the Schwarzwald, Germany, and of magnetite from the metamorphic Biwabik iron formation have been determined. The results show that a precision of better than 0.1‰ (2 sigma) can be achieved with laser ablation and that all the results obtained agree with those determined by solution ICP to better than 0.1‰. This precision and accuracy is achievable in both raster and spot ablation mode. A matrix-matched bracketing standard is not required , and all these materials can be measured accurately against a metal standard. The hydrothermal minerals show significant Fe isotope zonations. In some samples the range of δ56Fe in a single aggregate encompasses the entire spectrum of ratios found by bulk solution analyses in multiple samples distributed over the whole mining district. For example, isotopic zonations found in secondary fibrous hematites show a continuous change in the δ56Fe values from -0.5‰ in the core to -1.8‰ in the rim. Primary hydrothermal siderite shows the reverse pattern with lighter values in the core than in the rim. While the siderite is thought to record primary fluid histories, the hematite pattern is interpreted as a reworked isotopic signature generated by oxic dissolution of primary zoned siderite and

  14. Distribution of buried hydrothermal alteration deduced from high-resolution magnetic surveys in Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Bouligand, Claire; Glen, Jonathan M. G.; Blakely, Richard J.

    2014-04-01

    Yellowstone National Park (YNP) displays numerous and extensive hydrothermal features. Although hydrothermal alteration in YNP has been extensively studied, the volume, geometry, and type of rock alteration at depth remain poorly constrained. In this study, we use high-resolution airborne and ground magnetic surveys and measurements of remanent and induced magnetization of field and drill core samples to provide constraints on the geometry of hydrothermal alteration within the subsurface of three thermal areas in YNP (Firehole River, Smoke Jumper Hot Springs, and Norris Geyser Basin). We observe that hydrothermal zones from both liquid- and vapor-dominated systems coincide with magnetic lows observed in aeromagnetic surveys and with a decrease of the amplitude of short-wavelength anomalies seen in ground magnetic surveys. This suggests a strong demagnetization of both the shallow and deep substratum within these areas associated with the removal of magnetic minerals by hydrothermal alteration processes. Such demagnetization is confirmed by measurements of rock samples from hydrothermal areas which display significantly decreased total magnetization. A pronounced negative anomaly is observed over the Lone Star Geyser and suggests a significant demagnetization of the substratum associated with areas displaying large-scale fluid flow. The ground and airborne magnetic surveys are used to evaluate the distribution of magnetization in the subsurface. This study shows that significant demagnetization occurs over a thickness of at least a few hundred meters in hydrothermal areas at YNP and that the maximum degree or maximum thickness of demagnetization correlates closely with the location of hydrothermal activity and mapped alteration.

  15. Hydrothermal alteration, ore fluid characteristics, and gold depositional processes along a trondhjemite-komatiite contact at Tarmoola, Western Australia

    USGS Publications Warehouse

    Duuring, P.; Hagemann, S.G.; Cassidy, K.F.; Johnson, C.A.

    2004-01-01

    Tarmoola is a structurally controlled Archean orogenic gold deposit hosted in greenschist facies metamorphosed komatiite and trondhjemite in the Leonora district of the Eastern Goldfields province, Yilgarn craton. High-grade (>1 g/t Au) orebodies are located in komatiite wall rock adjacent to the eastern and northeastern margins of the asymmetrical, north-south-striking, Tarmoola trondhjemite intrusion. Gold-bearing veins post-date trondhjemite emplacement (ca. 2700 Ma), quartz diorite dikes (ca. 2667 Ma), and regional greenschist facies metamorphism. Textures and crosscutting relationships in gold-bearing veins indicate two stages of hydrothermal fluid infiltration associated with a single gold-related hydrothermal event: a volumetrically dominant, but gold-poor, stage I fluid and a gold-rich stage II fluid. Gold-bearing veins contain stage I milky quartz and pyrite that are overprinted by stage II quartz-ankerite-muscovite-chalcopyrite-sphalerite-galena-gold-tellurides ?? albite ?? chlorite ?? fuchsite ?? epidote ?? scheelite. Stage I hydrothermal alteration assemblages are different in trondhjemite and komatiite due to contrasting reactions between a common ore fluid and disparate wall-rock chemistry. Stage II fluid-wall rock interaction was minor compared to stage I and is indicated by the overprinting of stage I mineral assemblages by stage II microveins. Wall-rock alteration proximal to veins in trondhjemite is characterized by replacement of igneous plagioclase, amphibole, biotite, and metamorphic chlorite by hydrothermal quartz, muscovite, ankerite, calcite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold, whereas in proximal alteration in komatiite, metamorphic chlorite and talc are replaced by ankerite, quartz, muscovite, albite, chlorite, fuchsite, pyrite, chalcopyrite, sphalerite, galena, tellurides, and gold. The stage II fluid was enriched in H2O, CO2, Si, Ca, K, Na, S, Au, Ag, Cu, Pb, W, Bi, As, Mo, Zn, and Te. Based on fluid inclusion

  16. Active anatase (0 0 1)-like surface of hydrothermally synthesized titania nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Qiang; Mogilevsky, Gregory; Wagner, George W.; Forstater, Jacob; Kleinhammes, Alfred; Wu, Yue

    2009-11-01

    Using 31P and 13C NMR with DFT calculations we demonstrate the exposed surface of titania nanotubes (TiNTs) is a stable, unterminated anatase (0 0 1)-like surface and is catalytically active under ambient conditions. We find that methanol dissociatively adsorbs on the surface of TiNTs agreeing with the predicted activity of surface dissociation of organic molecules on the crystalline (0 0 1)-anatase surface. We further examined the catalytic activity of anatase power, TiNT, and nanosheets in catalytic hydrolysis of S-[2-(diisopropylamino)ethyl]- O-ethyl methylphosphonothioate (VX) via 31P NMR and demonstrate that titanate-like nanosheets are inactive in the reaction owing to their hydroxylated (0 0 1) surface.

  17. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Knipping, Jaayke L.; Bilenker, Laura D.; Simon, Adam C.; Reich, Martin; Barra, Fernando; Deditius, Artur P.; Wälle, Markus; Heinrich, Christoph A.; Holtz, François; Munizaga, Rodrigo

    2015-12-01

    during ascent along regional-scale transcurrent faults promotes continued growth of the magmatic magnetite microlites from the Fe-rich magmatic-hydrothermal fluid, which manifests in magnetite rims that have trace element abundances consistent with growth from a magmatic-hydrothermal fluid. Mass balance calculations indicate that this process can leach and transport sufficient Fe from a magmatic source to form large IOA deposits such as Los Colorados. Furthermore, published experimental data demonstrate that a saline magmatic-hydrothermal ore fluid will scavenge significant quantities of metals such as Cu and Au from a silicate melt, and when combined with solubility data for Fe, Cu and Au, it is plausible that the magmatic-hydrothermal ore fluid that continues to ascend from the IOA depositional environment can retain sufficient concentrations of these metals to form iron oxide copper-gold (IOCG) deposits at lateral and/or stratigraphically higher levels in the crust. Notably, this study provides a new discrimination diagram to identify magnetite from Kiruna-type deposits and to distinguish them from IOCG, porphyry and Fe-Ti-V/P deposits, based on low Cr (<100 ppm) and high V (>500 ppm) concentrations.

  18. Vapor Discharges On Nevado Del Ruiz During The Recent Activity: Clues On The Composition Of The Deep Hydrothermal System And Its Effects On Thermal Springs

    NASA Astrophysics Data System (ADS)

    Inguaggiato, S.; Federico, C.; Chacon, Z.; Londono, J. M.; Alzate, D. M.; Gil, E.

    2015-12-01

    The Nevado del ruiz volcano (NdR, 5321m asl), one of the most active in Colombia, threatens about 600,000 people. The existence of an ice cap and several streams channeling in some main rivers increase the risk of lahars and mudflows in case of unrest, as occurred during the November 1985 eruption, which caused 20,000 casualties. The involvement of the local hydrothermal system has also produced in the past phreatic and phreatomagmatic activity, as in 1985 and 1989. After more than 7 years of relative stability, since 2010, the still ongoing phase of unrest has produced two small eruption in 2012, and still maintains in high levels of seismicity and SO2 degassing. In October 2013, a sampling campaign has been performed on thermal springs and streamwater, located at 2600-5000 m asl, analyzed for water chemistry and stable isotopes. By applying a model of steam-heating, based on mass and enthalpy balances, we have estimated the mass rate of steam discharging in the different steam-heated springs. The composition of the hottest thermal spring (Botero Londoño) is probably representative of a marginal part of the hydrothermal system, having a temperature of 250°C and low salinity (Cl ~1500 mg/l), which suggest a chiefly meteoric origin, as also confirmed by the isotope composition retrieved for the hydrothermal water. The vapour discharged at the steam vent "Nereidas" (3600 m asl) is hypothesised to be separated from a high-temperature hyrothermal system. Based on its composition and on literature data on fluid inclusions, we have retrieved the P-T-X conditions of the deep hydrothermal system, as well as its pH and fO2. The vapour feeding Nereidas would separate from a byphasic hydrothermal system characterised by the follow parameters: t= 315°C, P=19 MPa, NaCl= 15 %, CO2 = 9%, and similar proportion between liquid and vapour. Considering also the equilibria involving S-bearing gases and HCl, we obtain pH=2, fO2 fixed by FeO-Fe2O3 buffer, and [Cl]=12000 mg/l. Changes

  19. Geology and hydrothermal evolution of the Mothra Hydrothermal Field, Endeavour Segment, Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Glickson, Deborah A.; Kelley, Deborah S.; Delaney, John R.

    2007-06-01

    Detailed characterization of the Mothra Hydrothermal Field, the most southern and spatially extensive field on the Endeavour Segment of the Juan de Fuca Ridge, provides new insights into its geologic and hydrothermal development. Meter-scale bathymetry, side-scan sonar imagery, and direct dive observations show that Mothra is composed of six actively venting sulfide clusters spaced 40-200 m apart. Chimneys within each cluster have similar morphology and venting characteristics, and all clusters host a combination of active and extinct sulfide structures. Black smoker chimneys venting fluids above 300°C are rare, while more common lower-temperature, diffusely venting chimneys support dense colonies of macrofauna and bacterial mat. Hydrothermal sediment and extinct sulfide debris cover 10-15 m of the seafloor surrounding each vent cluster, obscuring the underlying basaltic substrate of light to moderately sedimented pillow, lobate, sheet, and chaotic flows, basalt talus, and collapse terrain. Extinct sulfide chimneys and debris between the clusters indicate that hydrothermal flow was once more widespread and that it has shifted spatially over time. The most prominent structural features in the axial valley at Mothra are regional (020°) trending faults and fissures and north-south trending collapse basins. The location of actively venting clusters within the field is controlled by (1) localization of fluid upflow along the western boundary fault zone, and diversion of these fluids by antithetic faults to feed vent clusters near the western valley wall, and (2) tapping of residual magmatic heat in the central part of the axial valley, which drives flow beneath vent clusters directly adjacent to the collapse basins 70-90 m east of the western valley wall. These processes form the basis for a model of axial valley and hydrothermal system development at Mothra, in which the field is initiated by an eruptive-diking episode and sustained through intense microseismicity

  20. Acoustic stratigraphy and hydrothermal activity within Epi Submarine Caldera, Vanuatu, New Hebrides Arc

    USGS Publications Warehouse

    Greene, H. Gary; Exon, N.F.

    1988-01-01

    Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua (an active submarine volcano off the southeastern tip of Epi) lavas. ?? 1988 Springer-Verlag New York Inc.

  1. Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites

    NASA Astrophysics Data System (ADS)

    Wirsen, Carl O.; Jannasch, Holger W.; Molyneaux, Stephen J.

    1993-06-01

    Chemosynthetic production of microbial biomass, determined by 14CO2 fixation and enzymatic (RuBisCo) activity, at the Mid-Atlantic Ridge (MAR) 23° and 26°N vent sites was found in various niches: warm water emissions, loosely rock-attached flocculent material, dense morphologically diverse bacterial mats covering the surfaces of polymetal sulfide deposits, and filamentous microbes on the carapaces of shrimp (Rimicaris exoculata). The bacterial mats on polymetal sulfide surfaces contained unicellular and filamentous bacteria which appeared to use as their chemolithotrophic electron or energy source either dissolved reduced minerals from vent emissions, mainly sulfur compounds, or solid metal sulfide deposits, mainly pyrite. Moderately thermophilic Chemosynthetic activity was observed in carbon dioxide fixation experiments and in enrichments, but no thermophilic aerobic sulfur oxidizers could be isolated. Both obligate and facultative chemoautotrophs growing at mesophilic temperatures were isolated from all chemosynthetically active surface scrapings. The obligate autotrophs could oxidize sterilized MAR natural sulfide deposits as well as technical pyrite at near neutral pH, in addition to dissolved reduced sulfur compounds. While the grazing by shrimp on the surface mats of MAR metal sulfide deposits was observed and deemed important, the animals' primary occurrence in dense swarms near vent emissions suggests that they were feeding at these sites, where conditions for Chemosynthetic growth of their filamentous microbial epiflora were optimal. The data show that the transformation of geothermal energy at the massive polymetal sulfide deposits of the MAR is based on the lithoautotrophic oxidation of soluble sulfides and pyrites into microbial biomass.

  2. Luminescence characteristics of impurities-activated ZnS nanocrystals prepared in microemulsion with hydrothermal treatment

    NASA Astrophysics Data System (ADS)

    Xu, S. J.; Chua, S. J.; Liu, B.; Gan, L. M.; Chew, C. H.; Xu, G. Q.

    1998-07-01

    Cu-, Eu-, or Mn-doped ZnS nanocrystalline phosphors were prepared at room temperature using a chemical synthesis method. Transmission electron microscopy observation shows that the size of the ZnS clusters is in the 3-18 nm range. New luminescence characteristics such as strong and stable visible-light emissions with different colors were observed from the doped ZnS nanocrystals at room temperature. These results strongly suggest that impurities, especially transition metals and rare-earth metals-activated ZnS nanoclusters form a new class of luminescent materials.

  3. Lead recovery from scrap cathode ray tube funnel glass by hydrothermal sulphidisation.

    PubMed

    Yuan, Wenyi; Meng, Wen; Li, Jinhui; Zhang, Chenglong; Song, Qingbin; Bai, Jianfeng; Wang, Jingwei; Li, Yingshun

    2015-10-01

    This research focused on the application of the hydrothermal sulphidisation method to separate lead from scrap cathode ray tube funnel glass. Prior to hydrothermal treatment, the cathode ray tube funnel glass was pretreated by mechanical activation. Under hydrothermal conditions, hydroxyl ions (OH(-)) were generated through an ion exchange reaction between metal ions in mechanically activated funnel glass and water, to accelerate sulphur disproportionation; no additional alkaline compound was needed. Lead contained in funnel glass was converted to lead sulphide with high efficiency. Temperature had a significant effect on the sulphidisation rate of lead in funnel glass, which increased from 25% to 90% as the temperature increased from 100 °C to 300 °C. A sulphidisation rate of 100% was achieved at a duration of 8 h at 300 °C. This process of mechanical activation and hydrothermal sulphidisation is efficient and promising for the treatment of leaded glass.

  4. U/Th geochronology of hydrothermal activity in Long Valley caldera: Little Hot Creek and the Blue Chert

    SciTech Connect

    Sturchio, N.C.; Binz, C.M.; Sorey, M.L.

    1986-01-01

    To better define the evolution of the Long Valley hydrothermal system, we have embarked on a program of U/Th age determinations of hydrothermal products from outcrops and drill cores within the caldera. The U/Th system is appropriate for determining ages less than about 350 Ka in suitable materials. Results presented are from dense chalcedonic silica veins, collected from base to top of the outcrop beginning 40 m N of hot spring LHC-1 in Little Hot Creek canyon, and from samples of the Blue Chert.

  5. A discussion of 'Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?'

    NASA Technical Reports Server (NTRS)

    Roedder, Edwin

    1990-01-01

    This paper presents arguments against the statement made by Koeberl et al. (1989) to the effect that various differences between the quartz of the three quartz pebbles from the Roter Kamm impact crater (Namibia) and the quartz of the pegmatites present in the basement rocks of this crater can be best interpreted as evidence that the pebbles were formed (or 'recrystallized') by a post-impact hydrothermal system. Arguments are presented that suggest that the three quartz pebbles are, most likely, fragments of a preimpact vein quartz of hydrothermal origin.

  6. Unveiling the transformation and bioavailability of dissolved organic matter in contrasting hydrothermal vents using fluorescence EEM-PARAFAC.

    PubMed

    Yang, Liyang; Zhuang, Wan-E; Chen, Chen-Tung Arthur; Wang, Bing-Jye; Kuo, Fu-Wen

    2017-03-15

    The submarine hydrothermal systems are extreme environments where active cycling of dissolved organic matter (DOM) may occur. However, little is known about the optical properties and bioavailability of hydrothermal DOM, which could provide valuable insights into its transformation processes and biogeochemical reactivity. The quantity, quality, and bioavailability of DOM were investigated for four very different hydrothermal vents east of Taiwan, using dissolved organic carbon (DOC), absorption spectroscopy, and fluorescence excitation-emission matrices-parallel factor analysis (EEM-PARAFAC). The DOC and absorption coefficient a280 were both lower in the two hydrothermal vents off the Orchid Island and on the Green Island than in the surrounding seawater and the two vents off the Kueishantao Island, indicating effective removals of DOM in the former two hydrothermal systems owing to possible adsorption/co-precipitation and thermal degradation respectively. The four hydrothermal DOM showed notable differences in the absorption spectral slope S275-295, humification index HIX, biological index BIX, EEM spectra, and the relative distributions of seven PARAFAC components. The results demonstrated a high diversity of chemical composition and transformation history of DOM under contrasting hydrothermal conditions. The little change in the hydrothermal DOC after 28-day microbial incubations indicated a low bioavailability of the bulk DOM, and different PARAFAC components showed contrasting bioavailability. The results have profound implications for understanding the biogeochemical cycling and environmental effects of hydrothermal DOM in the marine environments.

  7. Adsorptive separation and photocatalytic degradation of methylene blue dye on titanate nanotube powders prepared by hydrothermal process using metal Ti particles as a precursor.

    PubMed

    Hu, Keshui; Xiao, Xin; Cao, Xiufang; Hao, Rong; Zuo, Xiaoxi; Zhang, Xiaojing; Nan, Junmin

    2011-08-30

    Titanate nanotube powders (TNTPs) with the twofold removal ability, i.e. adsorptive separation and photocatalytic degradation, are synthesized under hydrothermal conditions using metal Ti particles as a precursor in the concentrated alkaline solution, and their morphology, structure, adsorptive and photocatalytic properties are investigated. Under hydrothermal conditions, the titanate nanotubes (TNTs) with pore diameter of 3-4nm are produced on the surface of metal Ti particles, and stacked together to form three-dimensional (3D) network with porous structure. The TNTPs synthesized in the autoclave at 130°C for 24h exhibits a maximum adsorption capability of about 197mg g(-1) in the neutral methylene blue (MB) solution (40mg L(-1)) within 90min, the adsorption process can be described by pseudo second-order kinetics model. Especially, in comparison with the adsorptive and the photocatalytic processes are performed in turn, about 50min can be saved through synchronously utilizing the double removal ability of TNTPs when the removal ratio of MB approaches 95% in MB solution (40mg L(-1)) at a solid-liquid (S/L) ratio of 1:8 under ultraviolet (UV) light irradiation. These 3D TNTPs with the twofold removal properties and easier separation ability for recycling use show promising prospect for the treatment of dye pollutants from wastewaters in future industrial application.

  8. From nanocorals to nanorods to nanoflowers nanoarchitecture for efficient dye-sensitized solar cells at relatively low film thickness: All Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Mali, Sawanta S.; Betty, Chirayath A.; Bhosale, Popatrao N.; Patil, Pramod S.; Hong, Chang Kook

    2014-06-01

    Simple and low temperature hydrothermal process is employed to synthesize exotic nanostructures of TiO2. The nanostructures are obtained merely by changing the nature of the precursors and processing parameters. The chloride and isopropoxide salts of titanium are used to grow high quality thin films comprising anatase nanocorals, rutile nanorods and rutile nanoflowers respectively. A novel route of addition of room temperature ionic liquid (RTIL) is used to synthesize hitherto unexplored nano-morphologies. The Bronsted Acidic Ionic Liquid [BAIL] 0.01 M, 1: 3-ethoxycarbonylethyl-1-methyl-imidazolium chloride [CMIM][HSO4] RTIL directed growth of TiO2 flowers with bunch of aligned nanorods are obtained. The structural, optical and morphological properties of hydrothermally grown TiO2 samples are studied with the different characterization techniques. The influence of these exotic nano-morphologies on the performance of dye sensitized solar cells (DSSCs) is investigated in detail. It is found that [CMIM][HSO4] can facilitate the formation of novel nanoflower morphology with uniform, dense, and collectively aligned in regular petal like oriented TiO2 nanorods and hence improves the dye adsorption and the photovoltaic performance of DSSCs, typically in short-circuit photocurrent and power conversion efficiency. A best power conversion efficiency of 6.63% has been achieved on a DSSC based on nanoflowers (TNF) film obtained from a [CMIM][HSO4] solution.

  9. From nanocorals to nanorods to nanoflowers nanoarchitecture for efficient dye-sensitized solar cells at relatively low film thickness: All Hydrothermal Process

    PubMed Central

    Mali, Sawanta S.; Betty, Chirayath A.; Bhosale, Popatrao N.; Patil, Pramod S.; Hong, Chang Kook

    2014-01-01

    Simple and low temperature hydrothermal process is employed to synthesize exotic nanostructures of TiO2. The nanostructures are obtained merely by changing the nature of the precursors and processing parameters. The chloride and isopropoxide salts of titanium are used to grow high quality thin films comprising anatase nanocorals, rutile nanorods and rutile nanoflowers respectively. A novel route of addition of room temperature ionic liquid (RTIL) is used to synthesize hitherto unexplored nano-morphologies. The Bronsted Acidic Ionic Liquid [BAIL] 0.01 M, 1: 3-ethoxycarbonylethyl-1-methyl-imidazolium chloride [CMIM][HSO4] RTIL directed growth of TiO2 flowers with bunch of aligned nanorods are obtained. The structural, optical and morphological properties of hydrothermally grown TiO2 samples are studied with the different characterization techniques. The influence of these exotic nano-morphologies on the performance of dye sensitized solar cells (DSSCs) is investigated in detail. It is found that [CMIM][HSO4] can facilitate the formation of novel nanoflower morphology with uniform, dense, and collectively aligned in regular petal like oriented TiO2 nanorods and hence improves the dye adsorption and the photovoltaic performance of DSSCs, typically in short-circuit photocurrent and power conversion efficiency. A best power conversion efficiency of 6.63% has been achieved on a DSSC based on nanoflowers (TNF) film obtained from a [CMIM][HSO4] solution. PMID:24975849

  10. Subsurface geology, ancient hydrothermal systems and crater excavation processes beneath Lake Rotomahana: Evidence from lithic clasts of the 1886 AD Rotomahana Pyroclastics

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Briggs, R. M.; Bowyer, D. A.

    2016-03-01

    The craters associated with the 1886 AD phreatomagmatic Rotomahana eruption, Okataina Volcanic Centre, New Zealand, and the near-vent geology are now hidden beneath Lake Rotomahana and its post-eruptive sediment fill. Lithic clasts from the near-vent lithic lapilli ash deposits of the Rotomahana Pyroclastics are used in this study to trace geological and geothermal conditions before the eruption, as well as vent excavation dynamics. Near-vent deposit characteristics were described in the field, representative lithic clasts were documented petrographically, and unaltered clasts were analysed for major and trace element compositions. The majority of the lithic clasts were rhyolites with subordinate ignimbrites and hydrothermally altered clasts, and trace siltstone and silicified clasts. The rhyolites were classified into four petrographic groups according to phenocryst content and assemblage and were more diverse with respect to geochemical compositions. Most of the rhyolite lithics in the Rotomahana Pyroclastics did not match the rhyolite domes exposed subaerially around the lake, but did have affinities with the pre-Matahina caldera Wairua Rhyolite, and potentially other older non-exposed domes. Ignimbrites most likely correlated either to the Matahina ignimbrite or older non-exposed units. Hydrothermally altered rhyolite and ignimbrite lithic clasts are common and suggest that there has been a long-lived hydrothermal system in this sector, possibly dating back to early activity of the Okataina Volcanic Centre. The diversity in lithic types indicate a spatial variation in country rock lithology and strength, which probably contributed to the vent position and morphology along the Rotomahana fissure.

  11. Hydrothermal alteration of surficial rocks at Solfatara (Campi Flegrei): Petrophysical properties and implications for phreatic eruption processes

    NASA Astrophysics Data System (ADS)

    Mayer, Klaus; Scheu, Bettina; Montanaro, Cristian; Yilmaz, Tim I.; Isaia, Roberto; Aßbichler, Donjá; Dingwell, Donald B.

    2016-06-01

    Solfatara crater is located within the Campi Flegrei caldera to the west of Naples (Italy). It is one of the largest fumarolic manifestations known, and the rocks hosting the hydrothermal system are affected by intense hydrothermal alteration. Alteration can result in changes of degassing behavior, and in the formation of a cap rock thereby increasing the probability of phreatic eruptions. Here, we investigate the effects of alunitic (solfataric) alteration on the mineralogy, the physical properties (porosity, density, permeability) and the mechanical properties (strength) of the rocks involved, as well as its influence on fragmentation and ejection behavior. Our results show that the pristine mineralogy of deposits from the vicinity of the Solfatara cryptodome and from Pisciarelli is almost completely replaced by amorphous silica and alunite. The differences in the degree of alteration among the samples series are reflected in the investigated properties and behavior as well as in the analysis of the experimentally generated particles. Alunitic alteration increases porosity and permeability, whereas it reduces density, elastic wave velocity and strength leading to higher fragmentation and ejection speeds for the sample series examined in this study. Our results also show that alteration results in the generation of a high fraction of fines (particle sizes < 10 μm) during fragmentation, mainly composed of alunite crystals. Due to their potential for inducing chronic disease, dispersion of such material should represent a serious health hazard on a local scale and the evaluation of precautions should be considered.

  12. Hydrothermal liquefaction of freshwater and marine algal biomass: A novel approach to produce distillate fuel fractions through blending and co-processing of biocrude with petrocrude.

    PubMed

    Lavanya, Melcureraj; Meenakshisundaram, Arunachalam; Renganathan, Sahadevan; Chinnasamy, Senthil; Lewis, David Milton; Nallasivam, Jaganathan; Bhaskar, Sailendra

    2016-03-01

    Biocrude was produced from Tetraselmis sp. - a marine alga and Arthrospira platensis - a fresh water alga using hydrothermal liquefaction (HTL) process. Considering the constraints in cultivating algae for replacing 100% petrocrude, this study evaluated the option of blending and co-processing algal biocrude with petrocrude. Biocrudes obtained from algal strains cultivated in fresh water and sea water were blended with petrocrude at 10% concentration and the characteristics were studied using FT-IR and CNS SIMDIST. True Boiling Point (TBP) distillation was carried out to assess yields and properties of distillates of blended biocrudes. Biocrudes obtained from both algae were light crudes and the blended crudes recorded distillate yields of 76-77 wt%. The yield of light naphtha fraction of biocrude blends was 29-30%; whereas the yield of diesel fraction was about 18%. This study proposes blending and co-processing of algal biocrude with petrocrude to produce drop-in biofuels.

  13. Molecular Diversity and Activity of Methanogens in the Subseafloor at Deep-Sea Hydrothermal Vents of the Pacific Ocean (Invited)

    NASA Astrophysics Data System (ADS)

    Huber, J. A.; Merkel, A.; Holden, J. F.; Lilley, M. D.; Butterfield, D. A.

    2009-12-01

    Methanogenesis is thought to represent one of the most ancient metabolic pathways on Earth, and methanogens may serve as important primary producers in warm crustal habitats at deep-sea hydrothermal vents. Many of these obligate chemolithoautotrophs depend solely on geochemically-derived energy and carbon sources and grow at high temperatures under strictly anaerobic conditions. A combined geochemical and microbiological approach was used to determine the distribution and molecular diversity of methanogens in low temperature diffuse vent fluids from the Endeavour Segment R2K ISS site, as well as Axial Seamount and volcanoes of the Mariana Arc. Geochemical data from hot and adjacent warm diffuse vent fluids provided chemical indicators to guide sample selection for detailed polymerase chain reaction (PCR)-based analysis of the key enzyme for methane formation, methyl-coenzyme M reductase (mcrA), as well as archaeal 16S rRNA genes. At most Endeavour vent sites, hydrogen concentrations were too low to support hydrogenotrophic methanogensis directly and only one diffuse site, Easter Island, had a positive signal for the mcrA gene. These sequences were most closely related to members of the order Methanococcales, as well as anaerobic methane oxidizers (ANME-1). The presence of ANME, which are rarely found in non-sedimented marine environments, is another line of evidence supporting the occurrence of buried sediments at Endeavour. At Axial, a number of diffuse vents have strong chemical indicators of methanogenesis. Methanogenic communities were detected at 3 sites on the southeast side of the caldera: the northern end of the 1998 lava flow, the International District, and on the pre-1987 lava flow. Time series work at Marker 113 showed that in 4 different years over the last 6 years methanogenic communities are active and abundant, suggesting a stable anaerobic, warm subseafloor habitat. Results show that members of the order Methanococcales dominate at this site

  14. Hydrothermal systems and volcano geochemistry

    USGS Publications Warehouse

    Fournier, R.O.

    2007-01-01

    The upward intrusion of magma from deeper to shallower levels beneath volcanoes obviously plays an important role in their surface deformation. This chapter will examine less obvious roles that hydrothermal processes might play in volcanic deformation. Emphasis will be placed on the effect that the transition from brittle to plastic behavior of rocks is likely to have on magma degassing and hydrothermal processes, and on the likely chemical variations in brine and gas compositions that occur as a result of movement of aqueous-rich fluids from plastic into brittle rock at different depths. To a great extent, the model of hydrothermal processes in sub-volcanic systems that is presented here is inferential, based in part on information obtained from deep drilling for geothermal resources, and in part on the study of ore deposits that are thought to have formed in volcanic and shallow plutonic environments.

  15. Parallel Activation in Bilingual Phonological Processing

    ERIC Educational Resources Information Center

    Lee, Su-Yeon

    2011-01-01

    In bilingual language processing, the parallel activation hypothesis suggests that bilinguals activate their two languages simultaneously during language processing. Support for the parallel activation mainly comes from studies of lexical (word-form) processing, with relatively less attention to phonological (sound) processing. According to…

  16. Distribution and mineralogy of platinum-group elements in altered chromitites of the Campo Formoso layered intrusion (Bahia State, Brazil): control by magmatic and hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Garuti, G.; Proenza, J. A.; Zaccarini, F.

    2007-03-01

    Polyphase, penetrative hydrothermal metasomatism in chromitites of the Campo Formoso layered intrusion produced spectacular chromite - ferrian chromite zoning and transformed the primary intercumulus silicates into a chlorite - serpentine - carbonate - talc assemblage. Alteration did not substantially modify the composition of chromite cores and the distribution of platinum-group elements (PGE) through the sequence of chromitite layers, which still are consistent with magmatic fractionation processes. Texture and composition of laurite and Os-Ir-Ru alloys included in chromite cores indicate that these PGM were not altered, and are probably magmaticin origin. In contrast, the PGM located in the intergranular chlorite matrix (laurite, Ir-Ru-Rh sulfarsenides and Pt-Pd compounds with Sb, Bi and Te) display evidence of hydrothermal reworking. These PGM are intimately intergrown with low-temperature Ni-sulfides. The paragenesis suggests that the Ni-sulfides-PGM assemblage formed at the expenses of unknown PGM precursors, which must have been originally present in the intercumulus silicate matrix. Mechanism of formation involves a sequence of dissolution-precipitation events controlled by variation of redox conditions during chromite alteration. The presence of a secondary ore mineral assemblage consisting of galena, bismuthinite, native antimony, and various Pb-Sb compounds suggests a possible contribution of fluids derived from the adjacent granite.

  17. Lithium manganese oxide (LiMn2O4) nanoparticles synthesized by hydrothermal method as adsorbent of lithium recovery process from geothermal fluid of Lumpur Sidoarjo

    NASA Astrophysics Data System (ADS)

    Noerochim, Lukman; Sapputra, Gede Panca Ady; Widodo, Amien

    2016-04-01

    Lumpur Sidoarjo is one of geothermal fluid types which has a great potential as source of lithium. Adsorption method with Lithium Manganese Oxide (LiMn2O4) as an adsorbent has been chosen for lithium recovery process due to low production cost and environmental friendly. LiMn2O4 was synthesized by hydrothermal method at 200 °C for 24 hrs, 48 hrs, and 72 hrs. As prepared LiMn2O4 powder is treated by acid treatment with 0.5 M HCl solution for 24 hrs. XRD test result reveals that all of as-prepared samples are indexed as spinel structure of LiMn2O4 (JCPDS card no 35-0782) with no impurity peaks detected. SEM images show that LiMn2O4 has nanoparticles morphology with particle size around 25 nm. The highest adsorption efficiency of adsorbent is obtained by sample hydrothermal for 72 hrs with 42.76%.

  18. Hydrothermal Liquefaction of Biomass

    SciTech Connect

    Elliott, Douglas C.

    2010-12-10

    Hydrothermal liquefaction technology is describes in its relationship to fast pyrolysis of biomass. The scope of work at PNNL is discussed and some intial results are presented. HydroThermal Liquefaction (HTL), called high-pressure liquefaction in earlier years, is an alternative process for conversion of biomass into liquid products. Some experts consider it to be pyrolysis in solvent phase. It is typically performed at about 350 C and 200 atm pressure such that the water carrier for biomass slurry is maintained in a liquid phase, i.e. below super-critical conditions. In some applications catalysts and/or reducing gases have been added to the system with the expectation of producing higher yields of higher quality products. Slurry agents ('carriers') evaluated have included water, various hydrocarbon oils and recycled bio-oil. High-pressure pumping of biomass slurry has been a major limitation in the process development. Process research in this field faded away in the 1990s except for the HydroThermal Upgrading (HTU) effort in the Netherlands, but has new resurgence with other renewable fuels in light of the increased oil prices and climate change concerns. Research restarted at Pacific Northwest National Laboratory (PNNL) in 2007 with a project, 'HydroThermal Liquefaction of Agricultural and Biorefinery Residues' with partners Archer-Daniels-Midland Company and ConocoPhillips. Through bench-scale experimentation in a continuous-flow system this project investigated the bio-oil yield and quality that could be achieved from a range of biomass feedstocks and derivatives. The project was completed earlier this year with the issuance of the final report. HydroThermal Liquefaction research continues within the National Advanced Biofuels Consortium with the effort focused at PNNL. The bench-scale reactor is being used for conversion of lignocellulosic biomass including pine forest residue and corn stover. A complementary project is an international collaboration with

  19. Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems

    NASA Technical Reports Server (NTRS)

    Shock, Everett L.; Mccollom, Thomas; Schulte, Mithell D.

    1995-01-01

    Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of reduced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of hydrothermal fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of hydrothermal systems at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic systems.

  20. Geochemical constraints on chemolithoautotrophic reactions in hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Shock, Everett L.; McCollom, Thomas; Schulte, Mitchell D.

    1995-06-01

    Thermodynamic calculations provide the means to quantify the chemical disequilibrium inherent in the mixing of redeuced hydrothermal fluids with seawater. The chemical energy available for metabolic processes in these environments can be evaluated by taking into account the pressure and temperature dependence of the apparent standard Gibbs free energies of reactions in the S-H2-H2O system together with geochemical constraints on pH, activities of aqueous sulfur species and fugacities of H2 and/or O2. Using present-day mixing of hydrothermal fluids and seawater as a starting point, it is shown that each mole of H2S entering seawater from hydrothermal fluids represents about 200,000 calories of chemical energy for metabolic systems able to catalyze H2S oxidation. Extrapolating to the early Earth, which was likely to have had an atmosphere more reduced than at present, shows that this chemical energy may have been a factor of two or so less. Nevertheless, mixing of hydrothermal fluids with seawater would have been an abundant source of chemical energy, and an inevitable consequence of the presence of an ocean on an initially hot Earth. The amount of energy available was more than enough for organic synthesis from CO2 or CO, and/or polymer formation, indicating that the vicinity of hydrothermal systems at the sea floor was an ideal location for the emergence of the first chemolithoautotrophic metabolic systems.

  1. Stable light isotope biogeochemistry of hydrothermal systems.

    PubMed

    Des Marais, D J

    1996-01-01

    The stable isotopic composition of the elements O, H, S and C in minerals and other chemical species can indicate the existence, extent, conditions and the processes (including biological activity) of hydrothermal systems. Hydrothermal alteration of the 18O/16O and D/H values of minerals can be used to detect fossil systems and delineate their areal extent. Water-rock interactions create isotopic signatures which indicate fluid composition, temperature, water-rock ratios, etc. The 18O/16O values of silica and carbonate deposits tend to increase with declining temperature and thus help to map thermal gradients. Measurements of D/H values can help to decipher the origin(s) of hydrothermal fluids. The 34S/32S and 13C/12C values of fluids and minerals reflect the origin of the S and C as well as oxygen fugacities and key redox processes. For example, a wide range of 34S/32S values which are consistent with equilibration below 100 degrees C between sulfide and sulfate can be attributed to sulfur metabolizing bacteria. Depending on its magnitude, the difference in the 13C/12C value of CO2 and carbonates versus organic carbon might be attributed either to equilibrium at hydrothermal temperatures or, if the difference exceeds 1% (10/1000), to organic biosynthesis. Along the thermal gradients of thermal spring outflows, the 13C/12C value of carbonates and 13C-depleted microbial organic carbon increases, principally due to the outgassing of relatively 13C-depleted CO2.

  2. A facile growth mechanism, structural, optical, dielectric and electrical properties of ZnSe nanosphere via hydrothermal process

    NASA Astrophysics Data System (ADS)

    Javed, Qurat-Ul-Ain; Baqi, Sabah; Abbas, Hussain; Bibi, Maryam

    2017-02-01

    Hydrothermal method was chosen as a convenient method to fabricate zinc selenide (ZnSe) nanoparticle materials. The prepared nanospheres were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), where its different properties were observed using UV-visible spectroscopy and LCR meter. It was found that the pure ZnSe nanoparticles have a Zinc blende structure with crystallite size 10.91 nm and in a spherical form with average diameter of 35 nm (before sonication) and 18 nm (after sonication) with wide band gap of 4.28 eV. It was observed that there is inverse relation of frequency with dielectric constant and dielectric loss while AC conductivity grows up by increasing frequency. Such nanostructures were determined to be effectively used in optoelectronic devices as UV detector and in those devices where high-dielectric constant materials are required.

  3. Three-dimensional sea-urchin-like hierarchical TiO{sub 2} microspheres synthesized by a one-pot hydrothermal method and their enhanced photocatalytic activity

    SciTech Connect

    Zhou, Yi; Huang, Yan; Li, Dang; He, Wenhong

    2013-07-15

    Graphical abstract: SEM images of the samples synthesized at different hydrothermal temperatures for 8 h: (a) 75; (b) 100; (c) 120; and (d) 140°C, followed by calcination at 450 °C for 2 h. Highlights: ► Effects of calcination temperature on the phase transformation were studied. ► Effects of hydrothermal temperature and time on the morphology growth were studied. ► A two-stage reaction mechanism for the formation was presented. ► The photocatalytic activity was evaluated under sunlight irradiation. ► Effects of calcination temperature on the photocatalytic activity were studied. - Abstract: Novel three-dimensional sea-urchin-like hierarchical TiO{sub 2} superstructures were synthesized on a Ti plate in a mixture of H{sub 2}O{sub 2} and NaOH aqueous solution by a facile one-pot hydrothermal method at a low temperature, followed by protonation and calcination. The results of series of electron microscopy characterizations suggested that the hierarchical TiO{sub 2} superstructures consisted of numerous one-dimensional nanostructures. The microspheres were approximately 2–4 μm in diameter, and the one-dimensional TiO{sub 2} nanostructures were up to 600–700 nm long. A two-stage reaction mechanism, i.e., initial growth and then assembly, was proposed for the formation of these architectures. The three-dimensional sea-urchin-like hierarchical TiO{sub 2} microstructures showed excellent photocatalytic activity for the degradation of Rhodamine B aqueous solution under sunlight irradiation, which was attributed to the special three-dimensional hierarchical superstructure, and increased number of surface active sites. This novel superstructure has promising use in practical aqueous purification.

  4. Thermal History of an Oceanic Core Complex, Atlantis Bank, Southwest Indian Ridge: Evidence for Hydrothermal Activity 2.6 Myr Off-Axis

    NASA Astrophysics Data System (ADS)

    Schwartz, J. J.; John, B. E.; Cheadle, M. J.; Reiners, P. W.; Baines, G.

    2004-12-01

    We report 26 new (U-Th)/He zircon dates from the Atlantis Bank Oceanic Core Complex (OCC), Southwest Indian Ridge. The low (~200 °C) closure temperature of the (U-Th)/He isotopic system, together with higher temperature (850 °C) crystallization ages from U-Pb zircon dating, allow us to constrain the timescales and rates of lower crustal cooling in oceanic crust. Samples from the detachment fault surface exposed at the sea floor, indicate that the denuded crust cooled rapidly through 200 °C in <1 Myr, yielding mean cooling rates >1200 °C/Myr, consistent with existing models for cooling of oceanic crust. However, samples collected along post-detachment, N-S- and E-W-trending fault scarps record (U-Th)/He ages averaging 2.6 Myr younger than their corresponding igneous crystallization ages. These ages are inconsistent with steady-state conductive cooling models for lower oceanic crust and cannot be explained by simple monotonic cooling. Instead, they record cooling through 200 °C when the crust was well outside the rift valley, ~36 km off-axis assuming a half spreading rate of 14km/Myr. These samples display extensive post-crystallization greenschist-facies alteration and contain metamorphic mineral assemblages of chlorite + actinolite ± hornblende ± epidote ± serpentine ± clay, consistent with hydrothermal alteration. Therefore, we suggest that these anomalously young (U-Th)/He zircon ages record localized thermal heating events associated with high- temperature (>300 °C) hydrothermal fluid flow along transform-parallel and transform-normal faults that were active outside the rift valley during transtension along the bounding Atlantis II transform fault. A significant component of the heat driving hydrothermal fluid flow may have been derived from underplated mafic magmas emplaced during transtension. The young (U-Th)/He ages therefore delimit zones of hydrothermal upflow, and record evidence of protracted hydrothermal circulation up to ~3 Myr off-axis at

  5. Thermal History of an Oceanic Core Complex, Atlantis Bank, Southwest Indian Ridge: Evidence for Hydrothermal Activity 2.6 Myr Off-Axis

    NASA Astrophysics Data System (ADS)

    Schwartz, J. J.; John, B. E.; Cheadle, M. J.; Reiners, P. W.; Baines, G.

    2007-12-01

    We report 26 new (U-Th)/He zircon dates from the Atlantis Bank Oceanic Core Complex (OCC), Southwest Indian Ridge. The low (~200 °C) closure temperature of the (U-Th)/He isotopic system, together with higher temperature (850 °C) crystallization ages from U-Pb zircon dating, allow us to constrain the timescales and rates of lower crustal cooling in oceanic crust. Samples from the detachment fault surface exposed at the sea floor, indicate that the denuded crust cooled rapidly through 200 °C in <1 Myr, yielding mean cooling rates >1200 °C/Myr, consistent with existing models for cooling of oceanic crust. However, samples collected along post-detachment, N-S- and E-W-trending fault scarps record (U-Th)/He ages averaging 2.6 Myr younger than their corresponding igneous crystallization ages. These ages are inconsistent with steady-state conductive cooling models for lower oceanic crust and cannot be explained by simple monotonic cooling. Instead, they record cooling through 200 °C when the crust was well outside the rift valley, ~36 km off-axis assuming a half spreading rate of 14km/Myr. These samples display extensive post-crystallization greenschist-facies alteration and contain metamorphic mineral assemblages of chlorite + actinolite ± hornblende ± epidote ± serpentine ± clay, consistent with hydrothermal alteration. Therefore, we suggest that these anomalously young (U-Th)/He zircon ages record localized thermal heating events associated with high- temperature (>300 °C) hydrothermal fluid flow along transform-parallel and transform-normal faults that were active outside the rift valley during transtension along the bounding Atlantis II transform fault. A significant component of the heat driving hydrothermal fluid flow may have been derived from underplated mafic magmas emplaced during transtension. The young (U-Th)/He ages therefore delimit zones of hydrothermal upflow, and record evidence of protracted hydrothermal circulation up to ~3 Myr off-axis at

  6. Hydrothermal impacts on trace element and isotope ocean biogeochemistry

    NASA Astrophysics Data System (ADS)

    German, C. R.; Casciotti, K. A.; Dutay, J.-C.; Heimbürger, L. E.; Jenkins, W. J.; Measures, C. I.; Mills, R. A.; Obata, H.; Schlitzer, R.; Tagliabue, A.; Turner, D. R.; Whitby, H.

    2016-11-01

    Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  7. Hydrothermal impacts on trace element and isotope ocean biogeochemistry

    PubMed Central

    Dutay, J.-C.; Heimbürger, L. E.; Jenkins, W. J.; Measures, C. I.; Mills, R. A.; Obata, H.; Turner, D. R.; Whitby, H.

    2016-01-01

    Hydrothermal activity occurs in all ocean basins, releasing high concentrations of key trace elements and isotopes (TEIs) into the oceans. Importantly, the calculated rate of entrainment of the entire ocean volume through turbulently mixing buoyant hydrothermal plumes is so vigorous as to be comparable to that of deep-ocean thermohaline circulation. Consequently, biogeochemical processes active within deep-ocean hydrothermal plumes have long been known to have the potential to impact global-scale biogeochemical cycles. More recently, new results from GEOTRACES have revealed that plumes rich in dissolved Fe, an important micronutrient that is limiting to productivity in some areas, are widespread above mid-ocean ridges and extend out into the deep-ocean interior. While Fe is only one element among the full suite of TEIs of interest to GEOTRACES, these preliminary results are important because they illustrate how inputs from seafloor venting might impact the global biogeochemical budgets of many other TEIs. To determine the global impact of seafloor venting, however, requires two key questions to be addressed: (i) What processes are active close to vent sites that regulate the initial high-temperature hydrothermal fluxes for the full suite of TEIs that are dispersed through non-buoyant hydrothermal plumes? (ii) How do those processes vary, globally, in response to changing geologic settings at the seafloor and/or the geochemistry of the overlying ocean water? In this paper, we review key findings from recent work in this realm, highlight a series of key hypotheses arising from that research and propose a series of new GEOTRACES modelling, section and process studies that could be implemented, nationally and internationally, to address these issues. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.

  8. Magnetic mapping of submarine hydrothermal systems at Marsili and Palinuro volcanoes from deep-towed magnetometer data

    NASA Astrophysics Data System (ADS)

    Caratori Tontini, F.; Bortoluzzi, G.; Carmisciano, C.; Cocchi, L.; de Ronde, C. E.; Ligi, M.; Muccini, F.

    2013-12-01

    We collected near-bottom magnetic data at Marsili and Palinuro volcanoes in the Southern Tyrrhenian Sea, by adding a magnetometer to a deep-towed sidescan sonar. Equivalent magnetization maps obtained by inversion of the recorded magnetic anomalies are analyzed to map alteration zones related to hydrothermal processes and are correlated with water-column and seafloor observations of hydrothermal activity. At Marsili volcano, we found a large elliptical area of low magnetization, confirming the existence of a large hydrothermal system located in proximity of the top cone, above the magma chamber. Palinuro volcano is characterized by hydrothermal venting located along the caldera walls, where the corresponding ring faults may provide preferred pathways for the upflow of the hydrothermal fluids.

  9. Impact-induced hydrothermal activity within the Haughton impact structure, arctic Canada: generation of a transient, warm, wet oasis

    NASA Astrophysics Data System (ADS)

    Osinski, Gordon R.; Spray, John G.

    2001-05-01

    Field studies and analytical scanning electron microscopy indicate that a hydrothermal system was created by the interaction of water with hot, impact-generated rocks following formation of the 24 km-diameter, 23 Ma Haughton impact structure. Hydrothermal alteration is recognized in two settings: within polymict impact breccias overlying the central portion of the structure, and within localized pipes in impact-generated concentric fault systems. The intra-breccia alteration comprises three varieties of cavity and fracture filling: (a) sulfide with carbonate, (b) sulfate, and (c) carbonate. These are accompanied by subordinate celestite, barite, fluorite, quartz and marcasite. Selenite is also developed, particularly in the lower levels of the impact breccia sheet. The fault-related hydrothermal alteration occurs in 1-7 m diameter subvertical pipes that are exposed for lengths of up 20 m. The pipes are defined by a monomict quartz-carbonate breccia showing pronounced Fe-hydroxide alteration. Associated sulfides include marcasite, pyrite and chalcopyrite. We propose three distinct stages in the evolution of the hydrothermal system: (1) Early Stage (>200 degC), with the precipitation of quartz (vapour phase dominated); (2) Main Stage (200-100 deg C), with the development of a two phase (vapour plus liquid) zone, leading to calcite, celestite, barite, marcasite and fluorite precipitation, and (3) Late Stage (<100 degC), with selenite and fibroferrite development through liquid phase-dominanted precipitation. We estimate that it took several tens of thousands of years to cool below 50 deg C following impact. During this time, Haughton supported a 14 km diameter crater lake and subsurface water system, providing a warmer, wetter niche relative to the surrounding terrain. The results also reveal how understanding the internal structure of impact craters is necessary in order to determine their plumbing and cooling systems.

  10. Preliminary results on the reproduction of a deep-sea snailfish Careproctus rhodomelas around the active hydrothermal vent on the Hatoma Knoll, Okinawa, Japan.

    PubMed

    Takemura, A; Tamotsu, S; Miwa, T; Yamamoto, H

    2010-11-01

    Deep-sea snailfish Careproctus rhodomelas were collected from an active hydrothermal vent using a remotely operated vehicle (R.O.V. Hyper-dolphin) and a pressurized device (Deep-Aquarium). Careproctus rhodomelas exhibited a cystovarian-type ovary containing a small number of developing oocytes at different stages, suggesting that the fish is a batch-spawner that spawns large eggs (c. 6·0 mm) several times within its life span. In vitro culture of the oocytes in the presence of human chorionic gonadotropin showed that oestradiol-17β production fluctuated with oocyte development, suggesting that the oocytes were at the vitellogenic stage.

  11. Fabrication of (Co,Mn)3O4/rGO Composite for Lithium Ion Battery Anode by a One-Step Hydrothermal Process with H2O2 as Additive

    PubMed Central

    Li, Zuohua; Cui, Yanhui; Chen, Jun; Deng, Lianlin

    2016-01-01

    Binary transition metal oxides have been regarded as one of the most promising candidates for high-performance electrodes in energy storage devices, since they can offer high electrochemical activity and high capacity. Rational designing nanosized metal oxide/carbon composite architectures has been proven to be an effective way to improve the electrochemical performance. In this work, the (Co,Mn)3O4 spinel was synthesized and anchored on reduced graphene oxide (rGO) nanosheets using a facile and single hydrothermal step with H2O2 as additive, no further additional calcination required. Analysis showed that this method gives a mixed spinel, i.e. (Co,Mn)3O4, having 2+ and 3+ Co and Mn ions in both the octahedral and tetrahedral sites of the spinel structure, with a nanocubic morphology roughly 20 nm in size. The nanocubes are bound onto the rGO nanosheet uniformly in a single hydrothermal process, then the as-prepared (Co,Mn)3O4/rGO composite was characterized as the anode materials for Li-ion battery (LIB). It can deliver 1130.6 mAh g-1 at current density of 100 mA g-1 with 98% of coulombic efficiency after 140 cycles. At 1000 mA g-1, the capacity can still maintain 750 mAh g-1, demonstrating excellent rate capabilities. Therefore, the one-step process is a facile and promising method to fabricate metal oxide/rGO composite materials for energy storage applications. PMID:27788161

  12. Fine-Scale Volcano-Tectonic Patterns Along the Hotspot and Non-Hotspot Influenced Fastest Spreading Parts of the East Pacific Rise, and Their Relation to Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    Hey, R.; Baker, E.; Lupton, J.; Kleinrock, M.; Martinez, F.; Naar, D.; Bohnenstiehl, D.; Pardee, D.; Massoth, G.; Rodrigo, C.; Gegg, S.; Reed, T.; Andersson, A.

    2001-12-01

    A broad Easter mantle plume appears to be having a major long-term effect on the evolution of the giant duelling propagator system between the Easter and Juan Fernandez microplates. It is driving long-term propagation of the West ridge of this system toward the south, although there are occasional episodes of duelling propagation of the East ridge towards the north. The West ridge segment nearest the hotspot is the most highly inflated segment and contains several intense hydrothermal vent areas, although the East ridge segment farthest from the hotspot has a higher percentage of axis with active hydrothermal activity. DSL-120 sidescan sonar and bathymetry data collected along the EPR segment axes between the Easter and Juan Fernandez microplates have been compiled into a Quicktime movie. This presentation method provides a fast overview of an immense amount of data, and facilitates comparisons between the hotspot influenced and non-hotspot influenced segments, as well as correlations between the structural data and hydrothermal patterns, with implications for hydrothermal prospecting along mid-ocean ridges. For example, in addition to strong correlations with axial inflation and spreading rate, hydrothermal activity frequently correlates with areas of recent voluminous low-backscatter flows pouring out of axial fissures. Hydrothermal activity shows good correlation with presence of axial summit collapse structures, but not with the presence of an axial summit graben (sensu strictu). Although on a million year timescale the hotspot influence on the West ridge has a dominant effect on the tectonic evolution of this area, on the shorter timescales governing hydrothermal activity the hotspot influence is much less important than individual magmatic inflation events along individual ridge segments.

  13. Template-free synthesis of CdS hollow nanospheres based on an ionic liquid assisted hydrothermal process and their application in photocatalysis

    SciTech Connect

    Li Xinping; Gao Yanan; Yu Li; Zheng Liqiang

    2010-06-15

    Polycrystalline CdS hollow nanospheres with diameter of about 130 nm have been successfully synthesized in high yield by an ionic liquid (IL) assisted template-free hydrothermal method for the first time. Both the molar ratios of Cd/S precursor in the solution and the reaction temperature play important roles in the formation of the CdS hollow nanospheres. The concentrations of capping agent hexamethylenetetramine (HMT) and polyvinylpyrrolidone (PVP) are also crucial for the morphology and size of the final product. IL was found to be a key component in the formation of CdS hollow structures, because solid spheres were obtained in the absence of IL. A subsequent growth mechanism of hollow interior by localized Ostwald ripening process has been further discussed. Such hollow structures show high photocatalytic ability in the photodegradation of methylene blue. - Graphical abstract: TEM images of typical as-prepared CdS hollow nanospheres.

  14. Synthesis of an attapulgite clay@carbon nanocomposite adsorbent by a hydrothermal carbonization process and their application in the removal of toxic metal ions from water.

    PubMed

    Chen, Li-Feng; Liang, Hai-Wei; Lu, Yang; Cui, Chun-Hua; Yu, Shu-Hong

    2011-07-19

    A new kind of attapulgite clay@carbon (ATP@C) nanocomposite adsorbent has been synthesized by a one-pot hydrothermal carbonization process under mild conditions using two cheap, ecofriendly materials (i.e., attapulgite clay (ATP), which is a magnesium aluminum silicate that is abundant in nature, and glucose, which is a green chemical obtained from biomass). Compared to carbon-based materials, this new ATP@C nanocomposite exhibits a high adsorption ability for Cr(VI) and Pb(II) ions with maximum adsorption capacities of 177.74 and 263.83 mg·g(-1), respectively. The results demonstrate that this nanocomposite is an exceptionally promising candidate as a low-cost, sustainable, and effective adsorbent for the removal of toxic ions from water.

  15. Petrological and geochemical Highlights in the floating fragments of the October 2011 submarine eruption offshore El Hierro (Canary Islands): Relevance of submarine hydrothermal processes

    NASA Astrophysics Data System (ADS)

    Rodriguez-Losada, Jose A.; Eff-Darwich, Antonio; Hernandez, Luis E.; Viñas, Ronaldo; Pérez, Nemesio; Hernandez, Pedro; Melián, Gladys; Martinez-Frías, Jesús; Romero-Ruiz, M. Carmen; Coello-Bravo, Juan Jesús

    2015-02-01

    This paper describes the main physical, petrological and geochemical features of the floating fragments that were emitted in the initial stages of the 2011-2012 submarine eruption off the coast of the Canarian island of El Hierro, located 380 km from the Northwest African Coast. It attempts to assess the potential of radiometric analyses to discern the intriguing origin of the floating fragments and the differences between their constituent parts. In this regard, the material that conforms the core of the fragments contains the largest concentration of uranium (U) ever found in volcanic rocks of the Canary Islands. This enrichment in U is not found in the content of thorium (Th), hence the floating fragments have an unusual U/Th ratio, namely equal to or larger than 3. Although the origin of this material is under discussion, it is proposed that the enrichment in U is the result of hydrothermal processes.

  16. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-04-01

    Little is known about nitrogen (N) transformations in general, and the elimination of N in particular, at diffuse vents where anoxic hydrothermal fluids have mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N-loss pathways (denitrification, anammox) and dissimilative nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e. temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N-loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always <5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to 152 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlation existed between fixed N-loss (i.e., denitrification, anammox) rates and in-situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N-loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence

  17. Activity and abundance of denitrifying bacteria in the subsurface biosphere of diffuse hydrothermal vents of the Juan de Fuca Ridge

    NASA Astrophysics Data System (ADS)

    Bourbonnais, A.; Juniper, S. K.; Butterfield, D. A.; Devol, A. H.; Kuypers, M. M. M.; Lavik, G.; Hallam, S. J.; Wenk, C. B.; Chang, B. X.; Murdock, S. A.; Lehmann, M. F.

    2012-11-01

    Little is known about fixed nitrogen (N) transformation and elimination at diffuse hydrothermal vents where anoxic fluids are mixed with oxygenated crustal seawater prior to discharge. Oceanic N sinks that remove bio-available N ultimately affect chemosynthetic primary productivity in these ecosystems. Using 15N paired isotope techniques, we determined potential rates of fixed N loss pathways (denitrification, anammox) and dissimilatory nitrate reduction to ammonium (DNRA) in sulfidic hydrothermal vent fluids discharging from the subsurface at several sites at Axial Volcano and the Endeavour Segment on the Juan de Fuca Ridge. We also measured physico-chemical parameters (i.e., temperature, pH, nutrients, H2S and N2O concentrations) as well as the biodiversity and abundance of chemolithoautotrophic nitrate-reducing, sulfur-oxidizing γ-proteobacteria (SUP05 cluster) using sequence analysis of amplified small subunit ribosomal RNA (16S rRNA) genes in combination with taxon-specific quantitative polymerase chain reaction (qPCR) assays. Denitrification was the dominant N loss pathway in the subsurface biosphere of the Juan de Fuca Ridge, with rates of up to ~1000 nmol N l-1 day-1. In comparison, anammox rates were always < 5 nmol N l-1 day-1 and below the detection limit at most of the sites. DNRA rates were up to ~150 nmol N l-1 day-1. These results suggest that bacterial denitrification out-competes anammox in sulfidic hydrothermal vent waters. Taxon-specific qPCR revealed that γ-proteobacteria of the SUP05 cluster sometimes dominated the microbial community (SUP05/total bacteria up to 38%). Significant correlations were found between fixed N loss (i.e., denitrification, anammox) rates and in situ nitrate and dissolved inorganic nitrogen (DIN) deficits in the fluids, indicating that DIN availability may ultimately regulate N loss in the subsurface. Based on our rate measurements, and on published data on hydrothermal fluid fluxes and residence times, we estimated

  18. Morphology of hydrothermally synthesized ZnO nanoparticles tethered to carbon nanotubes affects electrocatalytic activity for H2O2 detection

    PubMed Central

    Wayu, Mulugeta B.; Spidle, Ryan T.; Devkota, Tuphan; Deb, Anup K.; Delong, Robert K.; Ghosh, Kartik C.; Wanekaya, Adam K.; Chusuei, Charles C.

    2013-01-01

    We describe the synthesis of zinc oxide (ZnO) nanoparticles and demonstrate their attachment to multiwalled carbon tubes, resulting in a composite with a unique synergistic effect. Morphology and size of ZnO nanostructures were controlled using hydrothermal synthesis, varying the hydrothermal treatment temperature, prior to attachment to carboxylic acid functionalized multi-walled carbon nanotubes for sensing applications. A strong dependence of electrocatalytic activity on nanosized ZnO shape was shown. High activity for H2O2 reduction was achieved when nanocomposite precursors with a roughly semi-spherical morphology (no needle-like particles present) formed at 90 °C. A 2.4-fold increase in cyclic voltammetry current accompanied by decrease in overpotential from the composites made from the nanosized, needle-like-free ZnO shapes was observed as compared to those composites produced from needle-like shaped ZnO. Electrocatalytic activity varied with pH, maximizing at pH 7.4. A stable, linear response for H2O2 concentrations was observed in the 1–20 mM concentration range. PMID:25684785

  19. Synthesis of Bi2WO6/Bi2O3 composite with enhanced photocatalytic activity by a facile one-step hydrothermal synthesis route.

    PubMed

    Wang, Tianye; Zhang, Fengjun; Xiao, Guosheng; Zhong, Shuang; Lu, Cong

    2015-01-01

    In this study, the characterization and photocatalytic activity of Bi2WO6/Bi2O3 under visible-light irradiation was investigated in detail. The results suggested that Bi2WO6/Bi2O3 can be synthesized by a facile one-pot hydrothermal route using a super big 200 mL Teflon-lined autoclave with optimal sodium oleate/Bi molar ratio of 1.25. Through the characterization of Bi2WO6/Bi2O3 by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared, UV-vis diffuse reflectance spectra and Photoluminescence spectra, it was found that the as-prepared composite possessed smaller crystallite size and higher visible-light responsive than the pure Bi2WO6. Moreover, it was expected that the as-prepared composites exhibited enhanced photocatalytic activity for the degradation of Rhodamine B under visible-light irradiation, which could be ascribed to their improved light absorption property and the reduced recombination of the photogenerated electrons and holes during the photocatalytic reaction. In general, this study could provide a principle method to synthesize Bi2WO6/Bi2O3 with enhanced photocatalytic activity by one-step hydrothermal synthesis route for environmental purification.

  20. Hydrothermal fabrication of N-doped (BiO)2CO3: Structural and morphological influence on the visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Dong, Fan; Wang, Rui; Li, Xinwei; Ho, Wing-Kei

    2014-11-01

    Various 3D N-doped (BiO)2CO3 (N-BOC) hierarchical superstructures self-assembled with 2D nanosheets were fabricated by one-step hydrothermal treatment of bismuth citrate and urea. The as-obtained samples were characterized by XRD, XPS, FT-IR, SEM, N2 adsorption-desorption isotherms and UV-vis DRS. The hydrothermal temperature plays a crucial role in tuning the crystal and morphological structure of the samples. Adjusting the reaction temperature to 150, 180 and 210 °C, we obtained N-doped (BiO)2CO3 samples with corresponding attractive persimmon-like, flower-like and nanoflakes nano/microstructures. The photocatalytic activities of the samples were evaluated by removal of NO under visible and solar light irradiation. The results revealed that the N-doped (BiO)2CO3 hierarchical superstructures showed enhanced visible light photocatalytic activity compared to pure (BiO)2CO3 and TiO2-based visible light photocatalysts. The outstanding photocatalytic performance of N-BOC samples can be ascribed to the doped nitrogen and the special hierarchical structure. The present work could provide new perspectives in controlling the morphological structure and photocatalytic activity of photocatalyst for better environmental pollution control.