Hydrothermal Processing of Base Camp Solid Wastes To Allow Onsite Recycling

DTIC Science & Technology

2008-09-01

ER D C/ CE R L TR -0 8 -1 3 Hydrothermal Processing of Base Camp Solid Wastes To Allow Onsite Recycling Gary L. Gerdes, Deborah...release; distribution is unlimited. ERDC/CERL TR-08-13 September 2008 Hydrothermal Processing of Base Camp Solid Wastes To Allow Onsite Recycling...a technology to process domestic solid waste using a unique hydrothermal system. The process was successfully demonstrated at Forts Benning and

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.

Monitoring Endeavour vent field deep-sea ecosystem dynamics through NEPTUNE Canada seafloor observatory

NASA Astrophysics Data System (ADS)

Matabos, M.; NC Endeavour Science Team

2010-12-01

Mid-ocean ridges are dynamic systems where the complex linkages between geological, biological, chemical, and physical processes are not yet well understood. Indeed, the poor accessibility to the marine environment has greatly limited our understanding of deep-sea ecosystems. Undersea cabled observatories offer the power and bandwidth required to conduct long-term and high-resolution time-series observations of the seafloor. Investigations of mid-ocean ridge hydrothermal ecosystem require interdisciplinary studies to better understand the dynamics of vent communities and the physico-chemical forces that influence them. NEPTUNE Canada (NC) regional observatory is located in the Northeast Pacific, off Vancouver Island (BC, Canada), and spans ecological environments from the beach to the abyss. In September-October 2010, NC will be instrumenting its 5th node, including deployment of a multi-disciplinary suite of instruments in two vent fields on the Endeavour Segment of the Juan de Fuca Ridge. These include a digital camera, an imaging sonar for vent plumes and flow characteristics (i.e. COVIS), temperature resistivity probes, a water sampler and seismometers. In 2011, the TEMPO-mini, a new custom-designed camera and sensor package created by IFREMER for real-time monitoring of hydrothermal faunal assemblages and their ecosystems (Sarrazin et al. 2007), and a microbial incubator, will added to the network in the Main Endeavour and Mothra vent fields. This multidisciplinary approach will involve a scientific community from different institutions and countries. Significant experience aids in this installation. For example, video systems connected to VENUS and NC have led to the development of new experimental protocols for time-series observations using seafloor cameras, including sampling design, camera calibration and image analysis methodologies (see communication by Aron et al. and Robert et al.). Similarly, autonomous deployment of many of the planned instruments has informed their adoption to the cabled instrument array at the Endeavour hydrothermal vents. This provides a unique laboratory for researchers to conduct long-term, integrated studies of hydrothermal vent ecosystem dynamics in relation to environmental variability at different temporal scales. In addition to programmed time-series monitoring, the NC infrastructure will also permit manual and automated modification of observational protocols in response to natural events. This will enhance our ability to document how the entire ecosystem reacts to potentially critical but short-lived environmental forces (e.g. seismic events). Sarrazin et al 2007. TEMPO: a new ecological module for studying deep-sea community dynamics at hydrothermal vents. OCEANS’07 IEEE Aberdeen Conference Proceedings

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 ...

Heterotrophic Proteobacteria in the vicinity of diffuse hydrothermal venting.

PubMed

Meier, Dimitri V; Bach, Wolfgang; Girguis, Peter R; Gruber-Vodicka, Harald R; Reeves, Eoghan P; Richter, Michael; Vidoudez, Charles; Amann, Rudolf; Meyerdierks, Anke

2016-12-01

Deep-sea hydrothermal vents are highly dynamic habitats characterized by steep temperature and chemical gradients. The oxidation of reduced compounds dissolved in the venting fluids fuels primary production providing the basis for extensive life. Until recently studies of microbial vent communities have focused primarily on chemolithoautotrophic organisms. In our study, we targeted the change of microbial community compositions along mixing gradients, focusing on distribution and capabilities of heterotrophic microorganisms. Samples were retrieved from different venting areas within the Menez Gwen hydrothermal field, taken along mixing gradients, including diffuse fluid discharge points, their immediate surroundings and the buoyant parts of hydrothermal plumes. High throughput 16S rRNA gene amplicon sequencing, fluorescence in situ hybridization, and targeted metagenome analysis were combined with geochemical analyses. Close to diffuse venting orifices dominated by chemolithoautotrophic Epsilonproteobacteria, in areas where environmental conditions still supported chemolithoautotrophic processes, we detected microbial communities enriched for versatile heterotrophic Alpha- and Gammaproteobacteria. The potential for alkane degradation could be shown for several genera and yet uncultured clades. We propose that hotspots of chemolithoautotrophic life support a 'belt' of heterotrophic bacteria significantly different from the dominating oligotrophic microbiota of the deep sea. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

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

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

PubMed

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

2012-06-19

Molecular hydrogen (H(2)) is derived from the hydrothermal alteration of olivine-rich planetary crust. Abiotic and biotic processes consume H(2) to produce methane (CH(4)); however, the extent of either process is unknown. Here, we assess the temporal dependence and limit of abiotic CH(4) 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 CH(4) production increases to a maximum value related to magnetite catalyzation. By identifying the dynamics of CH(4) production, we kinetically model how the H(2) to CH(4) ratio may be used to assess the origin of CH(4) in deep subsurface serpentinization systems on Earth and Mars. Based on our model and available field data, low H(2)/CH(4) ratios (less than approximately 40) indicate that life is likely present and active.

Geologic field-trip guide to the volcanic and hydrothermal landscape of the Yellowstone Plateau

USGS Publications Warehouse

Morgan Morzel, Lisa Ann; Shanks, W. C. Pat; Lowenstern, Jacob B.; Farrell, Jamie M.; Robinson, Joel E.

2017-11-20

Yellowstone National Park, a nearly 9,000 km2 (~3,468 mi2) area, was preserved in 1872 as the world’s first national park for its unique, extraordinary, and magnificent natural features. Rimmed by a crescent of older mountainous terrain, Yellowstone National Park has at its core the Quaternary Yellowstone Plateau, an undulating landscape shaped by forces of late Cenozoic explosive and effusive volcanism, on-going tectonism, glaciation, and hydrothermal activity. The Yellowstone Caldera is the centerpiece of the Yellowstone Plateau. The Yellowstone Plateau lies at the most northeastern front of the 17-Ma Yellowstone hot spot track, one of the few places on Earth where time-transgressive processes on continental crust can be observed in the volcanic and tectonic (faulting and uplift) record at the rate and direction predicted by plate motion. Over six days, this field trip presents an intensive overview into volcanism, tectonism, and hydrothermal activity on the Yellowstone Plateau (fig. 1). Field stops are linked directly to conceptual models related to monitoring of the various volcanic, geochemical, hydrothermal, and tectonic aspects of the greater Yellowstone system. Recent interest in young and possible future volcanism at Yellowstone as well as new discoveries and synthesis of previous studies, (for example, tomographic, deformation, gas, aeromagnetic, bathymetric, and seismic surveys), provide a framework in which to discuss volcanic, hydrothermal, and seismic activity in this dynamic region.

Modeling microbial reaction rates in a submarine hydrothermal vent chimney wall

NASA Astrophysics Data System (ADS)

LaRowe, Douglas E.; Dale, Andrew W.; Aguilera, David R.; L'Heureux, Ivan; Amend, Jan P.; Regnier, Pierre

2014-01-01

The fluids emanating from active submarine hydrothermal vent chimneys provide a window into subseafloor processes and, through mixing with seawater, are responsible for steep thermal and compositional gradients that provide the energetic basis for diverse biological communities. Although several models have been developed to better understand the dynamic interplay of seawater, hydrothermal fluid, minerals and microorganisms inside chimney walls, none provide a fully integrated approach to quantifying the biogeochemistry of these hydrothermal systems. In an effort to remedy this, a fully coupled biogeochemical reaction-transport model of a hydrothermal vent chimney has been developed that explicitly quantifies the rates of microbial catalysis while taking into account geochemical processes such as fluid flow, solute transport and oxidation-reduction reactions associated with fluid mixing as a function of temperature. The metabolisms included in the reaction network are methanogenesis, aerobic oxidation of hydrogen, sulfide and methane and sulfate reduction by hydrogen and methane. Model results indicate that microbial catalysis is generally fastest in the hottest habitable portion of the vent chimney (77-102 °C), and methane and sulfide oxidation peak near the seawater-side of the chimney. The fastest metabolisms are aerobic oxidation of H2 and sulfide and reduction of sulfate by H2 with maximum rates of 140, 900 and 800 pmol cm-3 d-1, respectively. The maximum rate of hydrogenotrophic methanogenesis is just under 0.03 pmol cm-3 d-1, the slowest of the metabolisms considered. Due to thermodynamic inhibition, there is no anaerobic oxidation of methane by sulfate (AOM). These simulations are consistent with vent chimney metabolic activity inferred from phylogenetic data reported in the literature. The model developed here provides a quantitative approach to describing the rates of biogeochemical transformations in hydrothermal systems and can be used to constrain the role of microbial activity in the deep subsurface.

Coupling hydrothermal liquefaction and anaerobic digestion for energy valorization from model biomass feedstocks.

PubMed

Posmanik, Roy; Labatut, Rodrigo A; Kim, Andrew H; Usack, Joseph G; Tester, Jefferson W; Angenent, Largus T

2017-06-01

Hydrothermal liquefaction converts food waste into oil and a carbon-rich hydrothermal aqueous phase. The hydrothermal aqueous phase may be converted to biomethane via anaerobic digestion. Here, the feasibility of coupling hydrothermal liquefaction and anaerobic digestion for the conversion of food waste into energy products was examined. A mixture of polysaccharides, proteins, and lipids, representing food waste, underwent hydrothermal processing at temperatures ranging from 200 to 350°C. The anaerobic biodegradability of the hydrothermal aqueous phase was examined through conducting biochemical methane potential assays. The results demonstrate that the anaerobic biodegradability of the hydrothermal aqueous phase was lower when the temperature of hydrothermal processing increased. The chemical composition of the hydrothermal aqueous phase affected the anaerobic biodegradability. However, no inhibition of biodegradation was observed for most samples. Combining hydrothermal and anaerobic digestion may, therefore, yield a higher energetic return by converting the feedstock into oil and biomethane. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exploration and discovery in Yellowstone Lake: Results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

USGS Publications Warehouse

Morgan, L.A.; Shanks, Wayne C.; Lovalvo, D.A.; Johnson, S.Y.; Stephenson, W.J.; Pierce, K.L.; Harlan, S.S.; Finn, C.A.; Lee, G.; Webring, M.; Schulze, B.; Duhn, J.; Sweeney, R.; Balistrieri, L.

2003-01-01

Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (???1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem. Published by Elsevier Science B.V.

Mobility of rare earth element in hydrothermal process and weathering product: a review

NASA Astrophysics Data System (ADS)

Lintjewas, L.; Setiawan, I.

2018-02-01

The Rare Earth Element (REE), consists of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Lu, Ho, Er, Tm, Yb, are important elements to be used as raw materials of advanced technology such as semiconductors, magnets, and lasers. The research of REE in Indonesia has not been done. Several researches were conducted on granitic rocks and weathering product such as Bangka, Sibolga, West Kalimantan, West Sulawesi and Papua. REE can be formed by hydrothermal processes such as Bayan Obo, South China. The REE study on active hydrothermal system (geothermal) in this case also has the potential to produce mineral deposits. The purpose of this review paper is to know the mobility of REE on hydrothermal process and weathering products. Mobility of REE in the hydrothermal process can change the distribution patterns and REE content such as Ce, Eu, La, Lu, Nd, Sm, and Y. Another process besides the hydrothermal is weathering process. REE mobility is influenced by weathering products, where the REE will experience residual and secondary enrichment processes in heavier minerals.

Combined hydrothermal liquefaction and catalytic hydrothermal gasification system and process for conversion of biomass feedstocks

DOEpatents

Elliott, Douglas C.; Neuenschwander, Gary G.; Hart, Todd R.

2017-09-12

A combined hydrothermal liquefaction (HTL) and catalytic hydrothermal gasification (CHG) system and process are described that convert various biomass-containing sources into separable bio-oils and aqueous effluents that contain residual organics. Bio-oils may be converted to useful bio-based fuels and other chemical feedstocks. Residual organics in HTL aqueous effluents may be gasified and converted into medium-BTU product gases and directly used for process heating or to provide energy.

Geologic and hydrologic controls on the economic potential of hydrothermal systems associated with upper crustal plutons

NASA Astrophysics Data System (ADS)

Weis, Philipp; Driesner, Thomas; Scott, Samuel; Lecumberri-Sanchez, Pilar

2016-04-01

Heat and mass transport in hydrothermal systems associated with upper crustal magmatic intrusions can result in resources with large economic potential (Kesler, 1994). Active hydrothermal systems can form high-enthalpy geothermal reservoirs with the possibility for renewable energy production. Fossil continental or submarine hydrothermal systems may have formed ore deposits at variable crustal depths, which can be mined near today's surface with an economic profit. In both cases, only the right combination of first-order geologic and hydrologic controls may lead to the formation of a significant resource. To foster exploration for these hydrothermal georesources, we need to improve our understanding of subsurface fluxes of mass and energy by combining numerical process modelling, observations at both active and fossil systems, as well as knowledge of fluid and rock properties and their interactions in natural systems. The presentation will highlight the role of non-linear fluid properties, phase separation, salt precipitation, fluid mixing, permeability structure, hydraulic fracturing and the transition from brittle to ductile rock behavior as major geologic and hydrologic controls on the formation of high-enthalpy and supercritical geothermal resources (Scott et al., 2015), and magmatic-hydrothermal mineral resources, such as porphyry copper, massive sulfide and epithermal gold deposits (Lecumberri-Sanchez et al., 2015; Weis, 2015). References: Kesler, S. E., 1994: Mineral Resources, economics and the environment, New York, McMillan, 391. Lecumberri-Sanchez, P., Steele-MacInnis, M., Weis, P., Driesner, T., Bodnar, R.J. (2015): Salt precipitation in magmatic-hydrothermal systems associated with upper crustal plutons. Geology, v. 43, p. 1063-1066, doi:10.1130/G37163.1 Scott, S., Driesner, T., Weis, P. (2015): Geologic controls on supercritical geothermal resources above magmatic intrusions. Nature Communications, 6:7837 doi: 10.1038/ncomms8837 Weis, P. (2015): The dynamic interplay between saline fluid flow and rock permeability in magmatic-hydrothermal systems. Geofluids, 15, 350-371.

Direct catalytic hydrothermal liquefaction of spirulina to biofuels with hydrogen

NASA Astrophysics Data System (ADS)

Zeng, Qin; Liao, Hansheng; Zhou, Shiqin; Li, Qiuping; Wang, Lu; Yu, Zhihao; Jing, Li

2018-01-01

We report herein on acquiring biofuels from direct catalytic hydrothermal liquefaction of spirulina. The component of bio-oil from direct catalytic hydrothermal liquefaction was similar to that from two independent processes (including liquefaction and upgrading of biocrude). However, one step process has higher carbon recovery, due to the less loss of carbons. It was demonstrated that the yield and HHV of bio-oil from direct catalytic algae with hydrothermal condition is higher than that from two independent processes.

Cameras on the NEPTUNE Canada seafloor observatory: Towards monitoring hydrothermal vent ecosystem dynamics

NASA Astrophysics Data System (ADS)

Robert, K.; Matabos, M.; Sarrazin, J.; Sarradin, P.; Lee, R. W.; Juniper, K.

2010-12-01

Hydrothermal vent environments are among the most dynamic benthic habitats in the ocean. The relative roles of physical and biological factors in shaping vent community structure remain unclear. Undersea cabled observatories offer the power and bandwidth required for high-resolution, time-series study of the dynamics of vent communities and the physico-chemical forces that influence them. The NEPTUNE Canada cabled instrument array at the Endeavour hydrothermal vents provides a unique laboratory for researchers to conduct long-term, integrated studies of hydrothermal vent ecosystem dynamics in relation to environmental variability. Beginning in September-October 2010, NEPTUNE Canada (NC) will be deploying a multi-disciplinary suite of instruments on the Endeavour Segment of the Juan de Fuca Ridge. Two camera and sensor systems will be used to study ecosystem dynamics in relation to hydrothermal discharge. These studies will make use of new experimental protocols for time-series observations that we have been developing since 2008 at other observatory sites connected to the VENUS and NC networks. These protocols include sampling design, camera calibration (i.e. structure, position, light, settings) and image analysis methodologies (see communication by Aron et al.). The camera systems to be deployed in the Main Endeavour vent field include a Sidus high definition video camera (2010) and the TEMPO-mini system (2011), designed by IFREMER (France). Real-time data from three sensors (O2, dissolved Fe, temperature) integrated with the TEMPO-mini system will enhance interpretation of imagery. For the first year of observations, a suite of internally recording temperature probes will be strategically placed in the field of view of the Sidus camera. These installations aim at monitoring variations in vent community structure and dynamics (species composition and abundances, interactions within and among species) in response to changes in environmental conditions at different temporal scales. High-resolution time-series studies also provide a mean of studying population dynamics, biological rhythms, organism growth and faunal succession. In addition to programmed time-series monitoring, the NC infrastructure will also permit manual and automated modification of observational protocols in response to natural events. This will enhance our ability to document potentially critical but short-lived environmental forces affecting vent communities.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barkaoui, Sami; Haddaoui, Marwa; Dhaouadi, Hassouna, E-mail: dhaouadihassouna@yahoo.fr

Nanostructured tricobalt tetraoxide, Co{sub 3}O{sub 4}, was hydrothermally synthesized starting from cobalt dichloride hexahydrate (CoCl{sub 2}·6H{sub 2}O) and urea (H{sub 2}NCONH{sub 2}) as precursor and polyethylene glycol-400 (PEG-400) as a structure-directing agent. Uniform urchin-like nanostructures were hydrothermally obtained at 150 °C for 16 h, and the Co{sub 3}O{sub 4} morphology did not collapse after a subsequent calcination at 300 °C for 2 h. XRD measurements indicated that the average sizes of Co{sub 3}O{sub 4} particles prior and after heating at 300 °C are 64 and 44 nm, respectively. This material has been successfully used for the nanostructuration of screen-printed carbonmore » electrodes (SPCEs) which were used for the sensitive electrochemical detection of hydrogen peroxide (H{sub 2}O{sub 2}). The sensor is endowed with a large dynamic range (0.1 to 50 µM) and a limit of detection of 0.145 µM. The as obtained results show that the Co{sub 3}O{sub 4} nanomaterial could be a candidate to be used as sensors for the detection of analytes. - Graphical abstract: The nanowires appear to have a common center and grow to the outside along the radial direction. - Highlights: • Nanostructured was hydrothermally prepared using PEG-400. • Uniform urchin-like Co{sub 3}O{sub 4} nanostructures were hydrothermally obtained. • X-ray diffraction showed a cubic structure after calcinations process. • Nanostructured Co{sub 3}O{sub 4} was used for the sensitive electrochemical detection of H{sub 2}O{sub 2.} • The sensor is endowed with a large dynamic range 0.1 to 50 µM.« less

Exploration and discovery in Yellowstone Lake: results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

NASA Astrophysics Data System (ADS)

Morgan, L. A.; Shanks, W. C.; Lovalvo, D. A.; Johnson, S. Y.; Stephenson, W. J.; Pierce, K. L.; Harlan, S. S.; Finn, C. A.; Lee, G.; Webring, M.; Schulze, B.; Dühn, J.; Sweeney, R.; Balistrieri, L.

2003-04-01

'No portion of the American continent is perhaps so rich in wonders as the Yellow Stone' (F.V. Hayden, September 2, 1874) Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (˜1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem.

JPRS Report Science & Technology Japan

DTIC Science & Technology

1989-03-02

Oxychlorides MOCln_2 (Organic Metal Salts) Alkoxides M(OR)n Acetylacetonate M(C5H702)n Acetates M(C2H302)n Oxalates M(C204)n/2 2.2 Hydrolysis and Gel...more deeply understanding hydrothermal dynamics during not only a major rupture LOCA but also a minor rupture LOCA and clarifying the combination of... hydrothermal dynamics of the coolant from the beginning of LOCA to its end, using a scale model of PWR (pressurized water reactor). Under the ROSA-III Plan

Microbial processing of carbon in hydrothermal systems (Invited)

NASA Astrophysics Data System (ADS)

LaRowe, D.; Amend, J. P.

2013-12-01

Microorganisms are known to be active in hydrothermal systems. They catalyze reactions that consume and produce carbon compounds as a result of their efforts to gain energy, grow and replace biomass. However, the rates of these processes, as well as the size of the active component of microbial populations, are poorly constrained in hydrothermal environments. In order to better characterize biogeochemical processes in these settings, a quantitative relationship between rates of microbial catalysis, energy supply and demand and population size is presented. Within this formulation, rates of biomass change are determined as a function of the proportion of catabolic power that is converted into biomass - either new microorganisms or the replacement of existing cell components - and the amount of energy that is required to synthesize biomass. The constraints that hydrothermal conditions place on power supply and demand are explicitly taken into account. The chemical composition, including the concentrations of organic compounds, of diffuse and focused flow hydrothermal fluids, hydrothermally influenced sediment pore water and fluids from the oceanic lithosphere are used in conjunction with cell count data and the model described above to constrain the rates of microbial processes that influence the carbon cycle in the Juan de Fuca hydrothermal system.

Influence the dopant concentration on the photocatalytic activity: Dy3+, Eu3+ doped TiO2

NASA Astrophysics Data System (ADS)

Zikriya, Mohamed; Nadaf, Y. F.; Pramod, A. G.; Renuka, C. G.

2018-05-01

Titanium dioxide (TiO2) nanoparticles were synthesis by means of hydrothermal process from metatitanic acid. The impacts reaction temperature, stirring process and aging time on the morphology, the transfer of nanoparticles particles were characterized. The morphology of the nanoparticles was described in detail with scanning electron microscopy. In the dynamic of hydrothermal method, stirring can cut down the reaction time of change from particles to nanoparticles. As can be seen from the XRD patterns, the diffraction peaks get broadened as the Eu3+ focus is increased, proposing an orderly abatement in the grain size. The Crystallite size was calculated for pure, Dy3+ and Eu3+ doped TiO2 from diffraction plane by Sherrer's formula and it was found that 13 nm to 18 nm. From SEM images the majorities of TiO2 particles are oblate spheroid or spheroid and look looser, and some macropores could be seen on a few particles.

Electron beam combined with hydrothermal treatment for enhancing the enzymatic convertibility of sugarcane bagasse

NASA Astrophysics Data System (ADS)

Duarte, C. L.; Ribeiro, M. A.; Oikawa, H.; Mori, M. N.; Napolitano, C. M.; Galvão, C. A.

2012-08-01

The use of microbial cellulolytic enzymes is the most efficient process to liberate glucose from cellulose in biomass without the formation of fermentation inhibitors. A combination of pretreatment technologies is an alternative way to increase the access of enzymes to cellulose, and consequently, the conversion yield. In this way, the present study reports on the enzymatic hydrolysis of SCB submitted to three kinds of pretreatment: electron beam processing (EBP), and EBP followed by hydrothermal (TH) and diluted acid (AH) treatment. SCB samples were irradiated using a radiation dynamics electron beam accelerator, and then submitted to thermal and acid (0.1% sulfuric acid) hydrolysis for 40 and 60 min at 180 °C. These samples were submitted to enzymatic hydrolysis (EH) using commercial preparations, including Celluclast 1.5 L and beta-glycosidase. The addition of diluted acid improved TH treatment allowing for a shorter application time. EBP with 50 kGy increased the enzymatic hydrolysis yield of cellulose by 20% after TH and 30% after AH.

Computational Fluid Dynamics simulation of hydrothermal liquefaction of microalgae in a continuous plug-flow reactor.

PubMed

Ranganathan, Panneerselvam; Savithri, Sivaraman

2018-06-01

Computational Fluid Dynamics (CFD) technique is used in this work to simulate the hydrothermal liquefaction of Nannochloropsis sp. microalgae in a lab-scale continuous plug-flow reactor to understand the fluid dynamics, heat transfer, and reaction kinetics in a HTL reactor under hydrothermal condition. The temperature profile in the reactor and the yield of HTL products from the present simulation are obtained and they are validated with the experimental data available in the literature. Furthermore, the parametric study is carried out to study the effect of slurry flow rate, reactor temperature, and external heat transfer coefficient on the yield of products. Though the model predictions are satisfactory in comparison with the experimental results, it still needs to be improved for better prediction of the product yields. This improved model will be considered as a baseline for design and scale-up of large-scale HTL reactor. Copyright © 2018 Elsevier Ltd. All rights reserved.

New insights on the remarkable longevity of hydrothermal plumes over the Cleft segment of the Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Jellinek, M.; Carazzo, G.

2011-12-01

Observations of the temporal variability of hydrothermal activity over the Juan de Fuca Ridge provide valuable clues for understanding the dynamics of hydrothermal plumes in the deep ocean. Analyses of hydrothermal temperature and light attenuation anomalies show that the structure of these plumes varies on an interannual rather than weekly or monthly time scale. This surprising stability is in complete disagreement with calculations of the residence time for the suspended particles, which suggest a complete particle sedimentation within a few days or weeks. In order to understand this difference, we performed analog experiments simulating particle-laden hydrothermal plumes. These experiments consist in injecting upwards at a fixed rate a hot mixture of fresh water and solid particles in a tank containing stratified salt water. Measurements of light attenuation, temperature and salinity anomalies are conducted during the experiments in order to decipher the causal links between real-time observations and venting conditions. Our results show that depending on the source conditions and the strength of density stratification in the tank, large-scale instabilities may develop due to the differential diffusion of heat and fine particles. Diffusive particle convection enhances the dispersion of fine particles and increases the longevity of the plume. We show that this process is a common phenomenon in natural submarine plumes, which not only increases the longevity of the plumes up to at least 5 years, but also permits dissolution processes to occur providing large amounts of dissolved chemical species far from the point of emission. A new model for particle sedimentation from hydrothermal plumes is presented and tested against natural data collected over the Cleft segment of the Juan de Fuca Ridge between 1987 and 1991. This model is found to be in good agreement with measurements of the rate of change of light attenuation within the chronic plume overlying the north Cleft vent field. We find that this particular plume remained in suspension for 6.5 years but became undetectable after 5 years in good agreement with observations.

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.

Study on optimizing ultrasonic irradiation period for thick polycrystalline PZT film by hydrothermal method.

PubMed

Ohta, Kanako; Isobe, Gaku; Bornmann, Peter; Hemsel, Tobias; Morita, Takeshi

2013-04-01

The hydrothermal method utilizes a solution-based chemical reaction to synthesize piezoelectric thin films and powders. This method has a number of advantages, such as low-temperature synthesis, and high purity and high quality of the product. In order to promote hydrothermal reactions, we developed an ultrasonic assisted hydrothermal method and confirmed that it produces dense and thick lead-zirconate-titanate (PZT) films. In the hydrothermal method, a crystal growth process follows the nucleation process. In this study, we verified that ultrasonic irradiation is effective for the nucleation process, and there is an optimum irradiation period to obtain thicker PZT films. With this optimization, a 9.2-μm-thick PZT polycrystalline film was obtained in a single deposition process. For this film, ultrasonic irradiation was carried out from the beginning of the reaction for 18 h, followed by a 6 h deposition without ultrasonic irradiation. These results indicate that the ultrasonic irradiation mainly promotes the nucleation process. Copyright © 2012 Elsevier B.V. All rights reserved.

Geochemical Tracers of Processes Affecting the Formation of Seafloor Hydrothermal Fluids and Deposits in the Manus Back-Arc Basin

DTIC Science & Technology

2009-02-01

21 ° N East Pacific Rise . In Hydrothermal Processes at Seafloor Spreading Centers (ed. P. Rona, K. Boström, L. Laubier, and K. L. Smith), pp... hydrothermal fluids ( 21 ° N East Pacific Rise ) are taken from Mitra et al (1994) and Klinkhammer et al. (1994). The chemical composition...Measures C. I., Walden B., and Weiss R. F. (1985) Chemistry of submarine hydrothermal solutions at 21 ° N , East

The oscillation model of hydrothermal dynamics beneath Aso volcano, southwest Japan after small eruption on May 2011: A new understanding model using repeated absolute and relative gravity measurement

NASA Astrophysics Data System (ADS)

Sofyan, Yayan; Nishijima, Jun; Fujimitsu, Yasuhiro; Yoshikawa, Shin; Kagiyama, Tsuneomi; Ohkura, Takahiro

2016-01-01

At the end of 2010, the seismic activity in Aso volcano intensely increased and water level in the Nakadake crater decreased until early in 2011, then was followed by a small eruption in May 2011. After the eruption and heavy rain, the volcanic activity subsided to calm period, crater bottom was refilled with water, and water level increased in the Nakadake crater. The next tremor reappeared in 2014 and tracked to eruption in November 2014. This eruptive pattern and water level variation in the crater repeatedly appeared on the surface, and it should be related to the hydrothermal dynamics beneath Aso volcano. We initiated the gravity measurements in relation to hydrothermal dynamics in the subsurface of Aso volcano using Scintrex CG-5 (549) and LaCoste Romberg type G-1016 relative gravimeter at 28 benchmarks in April 2011, one month before the eruption. The repeated gravity measurements continue to monitor Aso volcano with a series of the measurement after the eruption in every three months to a half year. We analyze the gravity variation from 2011 to 2014 between the time of the phreatic and strombolian eruption. The measurements covered the area more than 60 km2 in the west side of Aso caldera. A new gravity network was also installed in May 2010 at seven benchmarks using A10-017 absolute gravimeter, which re-occupied in October 2010, June 2011 and two benchmarks in June 2014. As a result, the gravity changes distinguish hydrothermal dynamic in the subsurface, which has a direct correlation to water level fluctuation in the crater, after the first eruption and before the second discharge. The monitoring data notice large gravity changes between the surveys at benchmarks around Nakadake crater and Kusasenri area. The simple 3D inversion models of the 4-D gravity data deduce the density contrast distribution beneath Aso volcano. The inversion and mass change result generate the oscillation typical as a new understanding model. The variation of the mass shows a similar trend with the hydrothermal input rate to the crater of past research. The third year monitoring from April 2013 displays a large gravity and mass variation, while precipitation data in this period is smaller than the previous season. The largest increased mass about 43 million tons by Gaussian method occurred between May 2013 and September 2013. According to the three year gravity monitoring, the calm period in Aso volcano happens after May 2011 eruption until September 2013, which is followed by the active period, before the November 2014 eruption. This result will contribute to understand the process of eruption.

Relationship between enhanced dewaterability and structural properties of hydrothermal sludge after hydrothermal treatment of excess sludge.

PubMed

Wang, Liping; Li, Aimin; Chang, Yuzhi

2017-04-01

Hydrothermal treatment is an effective method to enhance the deep dewaterability of excess sludge with low energy consumption. In this study, an insight into the relationship between enhanced dewaterability and structural properties of the produced hydrothermal sludge was presented, aiming at better understanding the effect of hydrothermal process on excess sludge dewatering performance. The results indicated that hydrothermal effect induced the transformation of surface water to interstitial and free water by lowering the binding strength between adjacent water and solid particles and that free water became the main form for moisture existence in hydrothermal sludge as temperature was higher than 180 °C. Increase in temperature of hydrothermal treatment generated a significant size reduction of sludge flocs but treated sludge with a higher rigidity, which not only strengthened the network of hydrothermal sludge but also destroyed the binding of EPS with water. Hydrothermal process caused crevice and pore structures of excess sludge to disappear gradually, which was a main driving force of water removal as temperature was below 150 °C. With the temperature of hydrothermal treatment exceeding 180 °C, the morphology of hydrothermal sludge became rough which linked closely to the solid precipitation of condensation polymerization, and further became smooth at higher temperature (210 °C) due to the coal-like structures with higher aromaticities, indicating that hydrothermal reaction pathways began to play a main role in enhanced dewaterability. Hydrothermal treatment led to more alkyl and aromatic carbon, but lower O-alkyl, carboxyl and carbonyl carbon. Copyright © 2017 Elsevier Ltd. All rights reserved.

CAREER: Hydrothermal vent flow and temperature fluctuations: exploring long-term variability through an integrated research and education program

NASA Astrophysics Data System (ADS)

Di Iorio, D.

2011-12-01

An acoustic scintillation system was built in partnership with ASL Environmental Sciences (Sidney BC Canada), which provided a unique opportunity for two engineering undergraduate students to live and work abroad. The acoustic instrumentation was tested in coastal waters and then deployed to study deep-sea hydrothermal plume dynamics. Undergraduate students were involved in the deployment of instrumentation and the development of processing software to give vertical velocities and temperature fluctuations from a vigorous hydrothermal vent. A graduate student thesis has yielded insights into the vertical and azimuthal dependence of entrainment and into plume bending and rise height. Teachers and Ocean Science Bowl students also participated in research cruises describing physical oceanography of estuaries, coastal waters, and deep-sea hydrothermal vents and participated in data collection, processing and analysis. Teachers used the knowledge they gained to develop creative educational curricula at their schools, to present their experiences at national conferences and to publish an article in the National Science Teachers Association - The Science Journal. One of the teachers was recently recognized with the Presidential Award for Excellence in Mathematics and Science Teaching. Working with the ocean bowl team at Oconee County High School has led to top ten placements in the national championships in 2005 (fourth place) and 2006 (sixth place). In order to increase quantitative methods in an undergraduate class, students acquire data from an ocean observatory and analyze the data for specific quantities of interest. One such project led to the calculation of the upper ocean heat content for the Greenland Sea using 7 years of Argo profiles, which showed a 0.04oC/year trend. These results were then published in JGR.

PROCESS IMPROVEMENT STUDIES ON THE BATTELLE HYDROTHERMAL COAL PROCESS

EPA Science Inventory

The report gives results of a study to improve the economic viability of the Battelle Hydrothermal (HT) Coal Process by reducing the costs associated with liquid/solid separation and leachant regeneration. Laboratory experiments were conducted to evaluate process improvements for...

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.

Microwave-Hydrothermal Treated Grape Peel as an Efficient Biosorbent for Methylene Blue Removal

PubMed Central

Ma, Lin; Jiang, Chunhai; Lin, Zhenyu; Zou, Zhimin

2018-01-01

Biosorption using agricultural wastes has been proven as a low cost and efficient way for wastewater treatment. Herein, grape peel treated by microwave- and conventional-hydrothermal processes was used as low cost biosorbent to remove methylene blue (MB) from aqueous solutions. The adsorption parameters including the initial pH value, dosage of biosorbents, contact time, and initial MB concentration were investigated to find the optimum adsorption conditions. The biosorbent obtained by microwave-hydrothermal treatment only for 3 min at 180 °C (microwave-hydrothermal treated grape peel, MGP) showed faster kinetics and higher adsorption capability than that produced by a conventional-hydrothermal process (hydrothermal treated grape peel, HGP) with a duration time of 16 h. The maximum adsorption capability of MGP under the optimum conditions (pH = 11, a dosage of 2.50 g/L) as determined with the Langmuir model reached 215.7 mg/g, which was among the best values achieved so far on biosorbents. These results demonstrated that the grape peel treated by a quick microwave-hydrothermal process can be a very promising low cost and efficient biosorbent for organic dye removal from aqueous solutions. PMID:29385041

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…

Geochemistry of High Temperature Vent Fluids in Yellowstone Lake: Dissolved Carbon and Sulfur Concentrations and Isotopic Data

NASA Astrophysics Data System (ADS)

Cino, C.; Seyfried, W. E., Jr.; Tan, C.; Fu, Q.

2017-12-01

Yellowstone National Park is a dynamic environment home to an array of geysers, hot springs, and hydrothermal vents fueled by the underlying continental magmatic intrusion. Yellowstone Lake vent fluids accounts for approximately 10% of the total geothermal flux for all of Yellowstone National Park. Though studying this remote hydrothermal system poses severe challenges, it provides an excellent natural laboratory to research hydrothermal fluids that undergo higher pressure and temperature conditions in an environment largely shielded from atmospheric oxygen. The location of these vents also provides chemistry that is characteristic of fluids deeper in the Yellowstone hydrothermal system. In August 2016, hydrothermal fluids were collected from the Stevenson Island vents in collaboration with the Hydrothermal Dynamics of Yellowstone Lake (HD-YLAKE) project using novel sampling techniques and monitoring instrumentation. The newly built ROV Yogi was deployed to reach the vents in-situ with temperatures in excess of 151oC at 100-120 m depth, equipped with a 12-cylinder isobaric sampler to collect the hydrothermal fluids. Results from geochemical analyses indicate the fluids are rich in gases such as CO2, CH4, and H2S, with sample concentrations of approximately 12 mM, 161 μm, and 2.1 mM respectively. However, lake water mixing with the hydrothermal endmember fluid likely diluted these concentrations in the collected samples. Isotopic analyses indicate CO2 has a δ13C of -6 indicating magmatic origins, however the CH4 resulted in a δ13C of -65 which is in the biological range. This biogenic signature is likely due to the pyrolysis of immature organic matter in the lake bottom sediment, since the high temperatures measured for the fluids would not allow the presence of methanogens. H2S concentrations have not been previously measured for the hydrothermal fluids in Yellowstone Lake, and our vent fluid samples indicate significantly higher H2S concentrations than reported for subaerial vents. The cause of these measured high dissolved H2S concentrations in Yellowstone Lake may result from temperature and/or redox effects.

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. Copyright © 2015. Published by Elsevier Ltd.

Numerical simulations (2D) on the influence of pre-existing local structures and seismic source characteristics in earthquake-volcano interactions

NASA Astrophysics Data System (ADS)

Farías, Cristian; Galván, Boris; Miller, Stephen A.

2017-09-01

Earthquake triggering of hydrothermal and volcanic systems is ubiquitous, but the underlying processes driving these systems are not well-understood. We numerically investigate the influence of seismic wave interaction with volcanic systems simulated as a trapped, high-pressure fluid reservoir connected to a fluid-filled fault system in a 2-D poroelastic medium. Different orientations and earthquake magnitudes are studied to quantify dynamic and static stress, and pore pressure changes induced by a seismic event. Results show that although the response of the system is mainly dominated by characteristics of the radiated seismic waves, local structures can also play an important role on the system dynamics. The fluid reservoir affects the seismic wave front, distorts the static overpressure pattern induced by the earthquake, and concentrates the kinetic energy of the incoming wave on its boundaries. The static volumetric stress pattern inside the fault system is also affected by the local structures. Our results show that local faults play an important role in earthquake-volcanic systems dynamics by concentrating kinetic energy inside and acting as wave-guides that have a breakwater-like behavior. This generates sudden changes in pore pressure, volumetric expansion, and stress gradients. Local structures also influence the regional Coulomb yield function. Our results show that local structures affect the dynamics of volcanic and hydrothermal systems, and should be taken into account when investigating triggering of these systems from nearby or distant earthquakes.

Modeling mid-ocean ridge hydrothermal response to earthquakes, tides, and ocean currents: a case study at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Xu, G.; Bemis, K. G.

2014-12-01

Seafloor hydrothermal systems feature intricate interconnections among oceanic, geological, hydrothermal, and biological processes. The advent of the NEPTUNE observatory operated by Ocean Networks Canada at the Endeavour Segment, Juan de Fuca Ridge enables scientists to study these interconnections through multidisciplinary, continuous, real-time observations. The multidisciplinary observatory instruments deployed at the Grotto Mound, a major study site of the NEPTUNE observatory, makes it a perfect place to study the response of a seafloor hydrothermal system to geological and oceanic processes. In this study, we use the multidisciplinary datasets recorded by the NEPTUNE Observatory instruments as observational tools to demonstrate two different aspects of the response of hydrothermal activity at the Grotto Mound to geological and oceanic processes. First, we investigate a recent increase in venting temperature and heat flux at Grotto observed by the Benthic and Resistivity Sensors (BARS) and the Cabled Observatory Vent Imaging Sonar (COVIS) respectively. This event started in Mar 2014 and is still evolving by the time of writing this abstract. An initial interpretation in light of the seismic data recorded by a neighboring ocean bottom seismometer on the NEPTUNE observatory suggests the temperature and heat flux increase is probably triggered by local seismic activities. Comparison of the observations with the results of a 1-D mathematical model simulation of hydrothermal sub-seafloor circulation elucidates the potential mechanisms underlying hydrothermal response to local earthquakes. Second, we observe significant tidal oscillations in the venting temperature time series recorded by BARS and the acoustic imaging of hydrothermal plumes by COVIS, which is evidence for hydrothermal response to ocean tides and currents. We interpret the tidal oscillations of venting temperature as a result of tidal loading on a poroelastic medium. We then invoke poroelastic theories to estimate the crustal permeability, a fundamental property of subsurface hydrothermal circulation, from the phase shift of the tidal oscillations of venting temperature relative to ambient ocean tides. These results together shed light on the influences of seismic and oceanic processes on a seafloor hydrothermal system.

Dynamics and characteristics of soil temperature and moisture of active layer in central Tibetan Plateau

NASA Astrophysics Data System (ADS)

Zhao, L.; Hu, G.; Wu, X.; Tian, L.

2017-12-01

Research on the hydrothermal properties of active layer during the thawing and freezing processes was considered as a key question to revealing the heat and moisture exchanges between permafrost and atmosphere. The characteristics of freezing and thawing processes at Tanggula (TGL) site in permafrost regions on the Tibetan Plateau, the results revealed that the depth of daily soil temperature transmission was about 40 cm shallower during thawing period than that during the freezing period. Soil warming process at the depth above 140 cm was slower than the cooling process, whereas they were close below 140 cm depth. Moreover, the hydro-thermal properties differed significantly among different stages. Precipitation caused an obviously increase in soil moisture at 0-20 cm depth. The vertical distribution of soil moisture could be divided into two main zones: less than 12% in the freeze state and greater than 12% in the thaw state. In addition, coupling of moisture and heat during the freezing and thawing processes also showed that soil temperature decreased faster than soil moisture during the freezing process. At the freezing stage, soil moisture exhibited an exponential relationship with the absolute soil temperature. Energy consumed for water-ice conversion during the freezing process was 149.83 MJ/m2 and 141.22 MJ/m2 in 2011 and 2012, respectively, which was estimated by the soil moisture variation.

The dynamics of Black Smokers: a heated-salty plume analog.

NASA Astrophysics Data System (ADS)

Maxworthy, Tony

2004-11-01

Experiments have been carried out on the dynamical processes that govern the evolution of hot, salty plumes injected into cold surroundings. Under the appropriate circumstances these are then used as an analoque system to understand some features of particle-laden, deep-ocean, hydrothermal plumes, e.g., Black Smokers. Details of the temperature distributions over a wide range of parameters are presented and these, coupled with flow visualization experiments, have yielded a fairly complete picture of the important features of the flow. As a result it has been concluded that cabelling processes are critical to an understanding of the flow reversals found in a certain parameter range and that double diffusive processes, though present, are of minor importance. As a final exercise an example is worked through in which the circumstances for flow reversal in deep-sea plumes have been estimated based on the best available knowledge of these interesting entities.

Learning about hydrothermal volcanic activity by modeling induced geophysical changes

NASA Astrophysics Data System (ADS)

Currenti, Gilda M.; Napoli, Rosalba

2017-05-01

Motivated by ongoing efforts to understand the nature and the energy potential of geothermal resources, we devise a coupled numerical model (hydrological, thermal, mechanical), which may help in the characterization and monitoring of hydrothermal systems through computational experiments. Hydrothermal areas in volcanic regions arise from a unique combination of geological and hydrological features which regulate the movement of fluids in the vicinity of magmatic sources capable of generating large quantities of steam and hot water. Numerical simulations help in understanding and characterizing rock-fluid interaction processes and the geophysical observations associated with them. Our aim is the quantification of the response of different geophysical observables (i.e. deformation, gravity and magnetic field) to hydrothermal activity on the basis of a sound geological framework (e.g. distribution and pathways of the flows, the presence of fractured zones, caprock). A detailed comprehension and quantification of the evolution and dynamics of the geothermal systems and the definition of their internal state through a geophysical modeling approach are essential to identify the key parameters for which the geothermal system may fulfill the requirements to be exploited as a source of energy. For the sake of illustration only, the numerical computations are focused on a conceptual model of the hydrothermal system of Vulcano Island by simulating a generic 1-year unrest and estimating different geophysical changes. We solved (i) the mass and energy balance equations of flow in porous media for temperature, pressure and density changes, (ii) the elastostatic equation for the deformation field and (iii) the Poisson’s equations for gravity and magnetic potential fields. Under the model assumptions, a generic unrest of 1-year engenders on the ground surface low amplitude changes in the investigated geophysical observables, that are, however, above the accuracies of the modern state-of-the-art instruments. Devising multidisciplinary and easy-to-use computational experiments enable us to learn how the hydrothermal system responds to un unrest and which fingerprints it may leave in the geophysical signals.

Destruction of Energetic Materials in Supercritical Water

DTIC Science & Technology

2002-06-25

PHASE BEHAVIOR UNDER HYDROTHERMAL PROCESSING CONDITIONS...172 E. MODELING TOOLS FOR SOLVATION FREE ENERGIES IN HYDROTHERMAL SYSTEMS...potential equations of state of hydrothermal solutions. Figure 25 shows a schematic of the transient grating experiment. In this experiment, two laser

Dynamic of the volcanic activity of La Soufrière volcano (Guadeloupe, Lesser Antillles): Evidence for shallow fluid seismic sources

NASA Astrophysics Data System (ADS)

Ucciani, G.; Beauducel, F.; Bouin, M. P.; Nercessian, A.

2015-12-01

La Soufrière is one of the many hazardous volcanoes in the inner arc of Lesser Antilles. Located South of Basse-Terre island, it is the only active volcano of the Guadeloupe archipelago. Since the last significant magmatic eruption in 1535 AD, the activity has been exculsively phreatic. Since 1992 and the abrupt renewal of seismic and fumarollic activities, the Guadeloupe Volcanological and Seismological Observatory (OVSG-IPGP) has recorded a progressive increasing of seismicity and degassing that led scientists and authorities to set the alert level ``Vigilance'' and hold it until today. According to the recent geophysical, geochemical and geological studies, the current volcanic activity of la Soufrière volcano seems to be exclusively associated to the hydrothermal system, while the link with seismic activity is still poorly studied. In this context of possible pre-eruptive unrest, we investigated the spatial and temporal variations of the seismicity recorded between 1981 and 2013. From a consistent seismological framework coupling spectral, statistical, signal processing, clustering, and inverse problems methods, we demonstrate that this seismicity is largely generated by shallow hydrothermal fluid sources located in a complex plumbing system. Spatial variations of Vp/Vs ratio and B-value in seismogenic structures allow us to document three main seismic zones associated to : (1) migration of magmatic gas, (2) the storage and mixing of underground water and gas and (3) the shallow migration of hydrothermal fluids in high fractured and heterogeneous system. Waveform analysis revealed a low number of significant families consistent with fracturing process, and the temporal evolution of multiplet activities highlighted several variations associated with surface manifestations and brutal dynamic changes after major local tectonic earthquakes of Les Saintes (21 November 2004, Mw=6.3), its main aftershock (14 February 2005, Mw=5.7) and the last major earthquake of la Martinique (29 November 2007, Mw=7.4).

Assessment of Japanese Technology in Advanced Glass and Ceramic Fibers

DTIC Science & Technology

1992-06-01

powders and crystals by hydrothermal tech- niques, and they have had their process for the preparation of zirconia powder commercial- ized by the...Masahiro Yoshimura. Whisker-Glass Composites, Hydrothermal Zirconia Powders , Hydrothermal Machining, Super-Conducting Thin Films. Professor Eiichi

Fracturing And Liquid CONvection

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-02-29

FALCON has been developed to enable simulation of the tightly coupled fluid-rock behavior in hydrothermal and engineered geothermal system (EGS) reservoirs, targeting the dynamics of fracture stimulation, fluid flow, rock deformation, and heat transport in a single integrated code, with the ultimate goal of providing a tool that can be used to test the viability of EGS in the United States and worldwide. Reliable reservoir performance predictions of EGS systems require accurate and robust modeling for the coupled thermal­hydrological­mechanical processes.

The Origin of Carbon-Bearing Volatiles in a Continental Hydrothermal System in the Great Basin: Water Chemistry and Isotope Characterizations

NASA Technical Reports Server (NTRS)

Fu, Qi; Socki, Richard A.; Niles, Paul B.; Romanek, Christopher; Datta, Saugata; Darnell, Mike

2012-01-01

Hydrothermal systems on Earth are active centers in the crust where organic molecules can be synthesized biotically or abiotically under a wide range of physical and chemical conditions [1-3]. Not only are volatile species (CO, CO2, H2, and hydrocarbons) a reflection of deep-seated hydrothermal alteration processes, but they also form an important component of biological systems. Studying carbon-bearing fluids from hydrothermal systems is of specific importance to understanding (bio-)geochemical processes within these systems. With recent detection of methane in the martian atmosphere [4-7] and the possibility of its hydrothermal origin [8, 9], understanding the formation mechanisms of methane may provide constraints on the history of the martian aqueous environments and climate.

Low archaeal diversity linked to subseafloor geochemical processes at the Lost City Hydrothermal Field, Mid-Atlantic Ridge.

PubMed

Schrenk, Matthew O; Kelley, Deborah S; Bolton, Sheryl A; Baross, John A

2004-10-01

The recently discovered Lost City Hydrothermal Field (LCHF) represents a new type of submarine hydrothermal system driven primarily by exothermic serpentinization reactions in ultramafic oceanic crust. Highly reducing, alkaline hydrothermal environments at the LCHF produce considerable quantities of hydrogen, methane and organic molecules through chemo- and biosynthetic reactions. Here, we report the first analyses of microbial communities inhabiting carbonate chimneys awash in warm, high pH fluids at the LCHF and the predominance of a single group of methane-metabolizing Archaea. The predominant phylotype, related to the Methanosarcinales, formed tens of micrometre-thick biofilms in regions adjacent to hydrothermal flow. Exterior portions of active structures harboured a diverse microbial community composed primarily of filamentous Eubacteria that resembled sulphide-oxidizing species. Inactive samples, away from regions of hydrothermal flow, contained phylotypes related to pelagic microorganisms. The abundance of organisms linked to the volatile chemistry at the LCHF hints that similar metabolic processes may operate in the subseafloor. These results expand the range of known geological settings that support biological activity to include submarine hydrothermal systems that are not dependent upon magmatic heat sources.

The impact of steeping, germination and hydrothermal processing of wheat (Triticum aestivum L.) grains on phytate hydrolysis and the distribution, speciation and bio-accessibility of iron and zinc elements.

PubMed

Lemmens, Elien; De Brier, Niels; Spiers, Kathryn M; Ryan, Chris; Garrevoet, Jan; Falkenberg, Gerald; Goos, Peter; Smolders, Erik; Delcour, Jan A

2018-10-30

Chelation of iron and zinc in wheat as phytates lowers their bio-accessibility. Steeping and germination (15 °C, 120 h) lowered phytate content from 0.96% to only 0.81% of initial dry matter. A multifactorial experiment in which (steeped/germinated) wheat was subjected to different time (2-24 h), temperature (20-80 °C) and pH (2.0-8.0) conditions showed that hydrothermal processing of germinated (15 °C, 120 h) wheat at 50 °C and pH 3.8 for 24 h reduced phytate content by 95%. X-ray absorption near-edge structure imaging showed that it indeed abolished chelation of iron to phytate. It also proved that iron was oxidized during steeping, germination and hydrothermal processing. It was further shown that zinc and iron bio-accessibility were respectively 3 and 5% in wheat and 27 and 37% in hydrothermally processed wheat. Thus, hydrothermal processing of (germinated) wheat paves the way for increasing elemental bio-accessibility in whole grain-based products. Copyright © 2018 Elsevier Ltd. All rights reserved.

Hydrothermal and alkaline hydrothermal pretreatments plus anaerobic digestion of sewage sludge for dewatering and biogas production: Bench-scale research and pilot-scale verification.

PubMed

Li, Chunxing; Wang, Xingdong; Zhang, Guangyi; Yu, Guangwei; Lin, Jingjiang; Wang, Yin

2017-06-15

To test the feasibility and practicability of the process combing hydrothermal pretreatment for dewatering with biogas production for full utilization of sewage sludge, hydrothermal/alkaline hydrothermal pretreatments and in turn anaerobic digestion of the filtrates obtained after dewatering the pretreated sludge were performed at bench- and pilot-scales. The hydrothermal temperature fell within the range of 140 °C-220 °C and the pretreatment time varied from 30 min to 120 min. For the alkaline hydrothermal pretreatment the pH value of the sludge was adjusted to 9.0-11.0 by adding Ca(OH) 2 . The results showed that the dewaterability of the sewage sludge was improved with increasing pretreatment temperature but the impact of the pretreatment time was not significant. The addition of Ca(OH) 2 gave better performance on the subsequent mechanical dewatering of the pretreated sludge compared to pure hydrothermal pretreatment, and the higher the pH value was, the better the dewaterability of the pretreated sludge was. The conditions of 180 °C/30 min and 160 °C/60 min/pH = 10.0 (for hydrothermal and alkaline hydrothermal pretreatments, respectively) resulted in relatively good results in the theoretical energy balance, which were verified in the pilot-scale tests. Based on the data from the pilot tests, the alkaline hydrothermal process realized self-sufficiency in energy at the cost of a proper amount of CaO. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Role of Siliceous Hydrothermal Breccias in the Genesis of Volcanic Massive Sulphide Deposits - Ancient and Recent Systems

NASA Astrophysics Data System (ADS)

Costa, I. A.; Barriga, F. J.; Fouquet, Y.

2014-12-01

Siliceous hydrothermal breccias were sampled in two Mid-Atlantic Ridge active sites: Lucky Strike and Menez Gwen. These hydrothermal fields are located in the border of the Azorean plateau, southwest of the Azores islands where the alteration processes affecting basaltic rocks are prominent (Costa et al., 2003). The hydrothermal breccias are genetically related with the circulation of low temperature hydrothermal fluids in diffuse vents. The groundmass of these breccias precipitates from the fluid and consolidates the clastic fragments mostly composed of basalt. The main sources are the surrounding volcanic hills. Breccias are found near hydrothermal vents and may play an important role in the protection of subseafloor hydrothermal deposits forming an impermeable cap due to the high content in siliceous material. The amorphous silica tends to precipitate when the fluid is conductively cooled as proposed by Fouquet et al. (1998) after Fournier (1983). The process evolves gradually from an initial stage where we have just the fragments and circulating seawater. The ascending hydrothermal fluid mixes with seawater, which favours the precipitation of the sulphide components. Sealing of the initially loose fragments begins, the temperature rises below this crust, and the processes of mixing fluid circulation and conductive cooling are simultaneous. At this stage the fluid becomes oversaturated with respect to amorphous silica. This form of silica can precipitate in the open spaces of the porous sulphides and seal the system. Normally this can happen at low temperatures. At this stage the hydrothermal breccia is formed creating a progressively less permeable, eventually impermeable cap rock at the surface. Once the fluid is trapped under this impermeable layer, conductive cooling is enhanced and mixing with seawater is restricted, making the precipitation of amorphous silica more efficient. Since the first discovery and description of recent mineralized submarine hydrothermal deposits, comparison with ancient volcanic massive sulphide deposits is appropriate. The proposed model can explain some of the processes taking place in the early phase of formation of old deposits where equivalent siliceous material is found in the hanging wall of the ore bodies (e.g. Barriga and Fyfe, 1988).

Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique

2016-07-01

Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the hydrothermal fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the hydrothermal system dynamics on the hazards associated to collapse-prone altered volcanic edifices.

Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics

PubMed Central

Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique

2016-01-01

Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the hydrothermal fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the hydrothermal system dynamics on the hazards associated to collapse-prone altered volcanic edifices. PMID:27457494

Volcano electrical tomography unveils edifice collapse hazard linked to hydrothermal system structure and dynamics.

PubMed

Rosas-Carbajal, Marina; Komorowski, Jean-Christophe; Nicollin, Florence; Gibert, Dominique

2016-07-26

Catastrophic collapses of the flanks of stratovolcanoes constitute a major hazard threatening numerous lives in many countries. Although many such collapses occurred following the ascent of magma to the surface, many are not associated with magmatic reawakening but are triggered by a combination of forcing agents such as pore-fluid pressurization and/or mechanical weakening of the volcanic edifice often located above a low-strength detachment plane. The volume of altered rock available for collapse, the dynamics of the hydrothermal fluid reservoir and the geometry of incipient collapse failure planes are key parameters for edifice stability analysis and modelling that remain essentially hidden to current volcano monitoring techniques. Here we derive a high-resolution, three-dimensional electrical conductivity model of the La Soufrière de Guadeloupe volcano from extensive electrical tomography data. We identify several highly conductive regions in the lava dome that are associated to fluid saturated host-rock and preferential flow of highly acid hot fluids within the dome. We interpret this model together with the existing wealth of geological and geochemical data on the volcano to demonstrate the influence of the hydrothermal system dynamics on the hazards associated to collapse-prone altered volcanic edifices.

Mapping Hydrothermal Alterations in the Muteh Gold Mining Area in Iran by using ASTER satellite Imagery data

NASA Astrophysics Data System (ADS)

Asadi Haroni, Hooshang; Hassan Tabatabaei, Seyed

2016-04-01

Muteh gold mining area is located in 160 km NW of Isfahan town. Gold mineralization is meso-thermal type and associated with silisic, seresitic and carbonate alterations as well as with hematite and goethite. Image processing and interpretation were applied on the ASTER satellite imagery data of about 400 km2 at the Muteh gold mining area to identify hydrothermal alterations and iron oxides associated with gold mineralization. After applying preprocessing methods such as radiometric and geometric corrections, image processing methods of Principal Components Analysis (PCA), Least Square Fit (Ls-Fit) and Spectral Angle Mapper (SAM) were applied on the ASTER data to identify hydrothermal alterations and iron oxides. In this research reference spectra of minerals such as chlorite, hematite, clay minerals and phengite identified from laboratory spectral analysis of collected samples were used to map the hydrothermal alterations. Finally, identified hydrothermal alteration and iron oxides were validated by visiting and sampling some of the mapped hydrothermal alterations.

Fluid Flow and Sound Generation at Hydrothermal Vent Fields

DTIC Science & Technology

1988-04-01

Pacific Rise The first evidence of vent sound generation came from data collected near hydrothermal vents at 21 N on the EPR where an array of ocean...associated with hydrothermal centers, one at 21 N on the East Pacific Rise (EPR) (Reidesel et al., 1982) and one on the Juan de Fuca Ridge (Bibee and Jacobson... East Pacific Rise at 210 N : the volcanic, tectonic and hydrothermal processes at

[Effect of sodium carbonate assisted hydrothermal process on heavy metals stabilization in medical waste incinerator fly ash].

PubMed

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

2010-04-01

A sodium carbonate assisted hydrothermal process was induced to stabilize the fly ash from medical waste incinerator. The results showed that sodium carbonate assisted hydrothermal process reduced the heavy metals leachability of fly ash, and the heavy metal waste water from the process would not be a secondary pollution. The leachability of heavy metals studied in this paper were Cd 1.97 mg/L, Cr 1.56 mg/L, Cu 2.56 mg/L, Mn 17.30 mg/L, Ni 1.65 mg/L, Pb 1.56 mg/L and Zn 189.00 mg/L, and after hydrothermal process with the optimal experimental condition (Na2CO3/fly ash dosage = 5/20, reaction time = 8 h, L/S ratio = 10/1) the leachability reduced to < 0.02 mg/L for Cd, Cr, Cu, Mn, Ni, Pb, and 0.05 mg/L for Zn, according to GB 5085.3-2007. Meanwhile, the concentrations of heavy metals in effluent after hydrothermal process were less than 0.8 mg/L. The heavy metals leachability and concentration in effluent reduced with prolonged reaction time. Prolonged aging can affect the leachability of metals as solids become more crystalline, and heavy metals transferred inside of crystalline. The mechanism of heavy metal stabilization can be concluded to the co precipitation and adsorption effect of aluminosilicates formation, crystallization and aging process.

Oman Drilling Project GT3 site survey: dynamics at the roof of an oceanic magma chamber

NASA Astrophysics Data System (ADS)

France, L.; Nicollet, C.; Debret, B.; Lombard, M.; Berthod, C.; Ildefonse, B.; Koepke, J.

2017-12-01

Oman Drilling Project (OmanDP) aims at bringing new constraints on oceanic crust accretion and evolution by drilling Holes in the whole ophiolite section (mantle and crust). Among those, operations at GT3 in the Sumail massif drilled 400 m to sample the dike - gabbro transition that corresponds to the top (gabbros) and roof (dikes) of the axial magma chamber, an interface where hydrothermal and magmatic system interacts. Previous studies based on oceanic crust formed at present day fast-spreading ridges and preserved in ophiolites have highlighted that this interface is a dynamic horizon where the axial melt lens that top the main magma chamber can intrude, reheat, and partially assimilate previously hydrothermally altered roof rocks. Here we present the preliminary results obtained in GT3 area that have allowed the community to choose the drilling site. We provide a geological and structural map of the area, together with new petrographic and chemical constraints on the dynamics of the dike - gabbro transition. Our new results allow us to quantify the dynamic processes, and to propose that 1/ the intrusive contact of the varitextured gabbro within the dikes highlights the intrusion of the melt lens top in the dike rooting zone, 2/ both dikes and previously crystallized gabbros are reheated, and recrystallized by underlying melt lens dynamics (up to 1050°C, largely above the hydrous solidus temperature of altered dikes and gabbros), 3/ the reheating range can be > 200°C, 4/ the melt lens depth variations for a given ridge position is > 200m, 5/ the reheating stage and associated recrystallization within the dikes occurred under hydrous conditions, 6/ the reheating stage is recorded at the root zone of the sheeted dike complex by one of the highest stable conductive thermal gradient ever recorded on Earth ( 3°C/m), 7/ local chemical variations in recrystallized dikes and gabbros are highlighted and used to quantify crystallization and anatectic processes, and the presence of trapped melt, 8/ melt lens cannibalism is attested by numerous assimilation figures close its roof. Besides providing a general context for future studies at OmanDP GT3 site, those new results allow us to quantify the dynamic processes that govern the layer 2 - layer 3 transition in ocean lithosphere.

[Elaboration of instant corn flour by hydrothermal process I].

PubMed

Martínez B, F; el-Dahs, A A

1993-12-01

The objective of this research was to investigate a simplified hydrothermal process for the production of instant corn flour and evaluate some variables that affected the degree of gelatinization of corn flour, and evaluate some technological characteristics of the flour. The use of grits of lesser particle diameter and increasing temperature of the soaking water resulted in an increase in the rate of absorption of water of grits, permitting a reduction of soaking time necessary for the process. The instant corn flour prepared by the hydrothermal process using corn grits soaked in water at room temperature (28-30 degrees C) for 5 hours and steaming for 1 minute at 118 degrees C presented characteristics of viscosity, water absorption index and water solubility index similar to that of flours prepared with grits soaked in water at a temperature higher tan room temperature and different steaming time (5 and 15 minutes). The characteristics of color and shelf life of corn flour were improved with the hydrothermal process.

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 ultraslow spreading ridges is also presumable.

Effect of acid detergent fiber in hydrothermally pretreated sewage sludge on anaerobic digestion process

NASA Astrophysics Data System (ADS)

Takasaki, Rikiya; Yuan, Lee Chang; Kamahara, Hirotsugu; Atsuta, Youichi; Daimon, Hiroyuki

2017-10-01

Hydrothermal treatment is one of the pre-treatment method for anaerobic digestion. The application of hydrothermal treatment to sewage sludge of wastewater treatment plant has been succeeded to enhance the biogas production. The purpose of this study is to quantitatively clarify the effect of hydrothermal treatment on anaerobic digestion process focusing on acid detergent fiber (ADF) in sewage sludge, which is low biodegradability. The hydrothermal treatment experiment was carried out for 15 minutes between 160 °C and 200 °C respectively. The ADF content was decreased after hydrothermal treatment compared with untreated sludge. However, ADF content was increased when raising the treatment temperature from 160 °C to 200 °C. During batch anaerobic digestion experiment, untreated and treated sludge were examined for 10 days under 38 °C, and all samples were fed once based on volatile solids of samples. From batch anaerobic digestion experiment, as ADF content in sewage sludge increased, the total biogas production decreased. It was found that ADF content in sewage sludge influence on anaerobic digestion. Therefore, ADF could be one of the indicator to evaluate the effect of hydrothermal treatment to sewage sludge on anaerobic digestion.

Improving the circular economy via hydrothermal processing of high-density waste plastics.

PubMed

Helmer Pedersen, Thomas; Conti, Federica

2017-10-01

Rising environmental concerns on climate changes are causing an increasing attention on circular economies. The plastic economy, in particular, is in focus due to the accelerating consumption of plastics, mainly derived from virgin feedstock, combined with the lack of plastic recycling strategies. This work presents a novel outlook on the potential of using supercritical hydrothermal processing of waste plastic fractions for tertiary recycling. The study investigates hydrothermal processing of nine different, high-density types of plastics into original resin monomers and other value-added chemical compounds. The outlook presents conversion yields, carbon balances, and chemical details on the products obtained. It is found that all the investigated resins are prone to hydrothermal treatment, and that high yields of monomers and high value compounds (up to nearly 100%), suitable for chemicals and fuels applications, can be obtained. For instance, for polycarbonate, styrene-butadiene, poly(lactic acid), poly(ethylene terephthalate), and poly(butylene terephthalate), original monomeric compounds can be reclaimed for manufacturing new resins. The promising results presented demonstrate that hydrothermal processing of high-density plastics is a prospective technology for increasing the circularity of the plastic economy. Copyright © 2017 Elsevier Ltd. All rights reserved.

A Hydrothermal Origin for the Sulfate-rich Ocean of Europa

NASA Technical Reports Server (NTRS)

Zolotov, M. Yu.; Shock, E. L.

2001-01-01

Thermodynamic calculations show that formation of a sulfate-rich ocean on Europa might require high-temperature alkaline hydrothermal processes in the oxidized silicate mantle. The ocean on Europa could be thought of as a cooled hydrothermal fluid. Additional information is contained in the original extended abstract.

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.

Effect of hydrothermal condition on the formation of multi-component oxides of Ni-based metallic glass under high temperature water near the critical point

DOE PAGES

Kim, J. S.; Kim, S. Y.; Kim, D. H.; ...

2015-07-01

The specific feature of multi-component oxides synthesized by hydrothermal process under high temperature (633 K) and highly pressurized water (18.9 MPa) near critical point. Effects of hydrothermal processing duration times 24 hours and 72 hours, respectively, on the oxide formation of the Ni 59Zr 20Ti 16Si 2Sn 3 metallic glass synthesized by powder metallurgy process were characterized by X-ray diffractometer, differential scanning calorimeter along with the particle size, morphology and crystalline phase of the oxides. The crystallization of the needle-shape NiTiO 3, ZrTiO 4 and ZrSnO 4 ternary oxide phases observed on the surface of metallic glass at below glassmore » transition temperature and the morphology of oxide phases changed to plate-shape around 2 μm in diameter by the increase processing time. This hydrothermal processing in subcritical water provides accelerated dense metal oxide crystals due to the reaction medium being at higher pressure than conventional oxidation processing.« less

Immobilization of LiCl-Li2O pyroprocessing salt wastes in chlorosodalite using glass-bonded hydrothermal and salt-occlusion methods

NASA Astrophysics Data System (ADS)

Riley, Brian J.; Peterson, Jacob A.; Kroll, Jared O.; Frank, Steven M.

2018-04-01

In this study, hydrothermal and salt-occlusion processes were used to make chlorosodalite through reactions with a high-LiCl salt simulating a waste stream generated from pyrochemical treatment of oxide-based used nuclear fuel. Some products were reacted with glass binders to increase chlorosodalite yield through alkali ion exchange and to aid in densification. Hydrothermal processes included reaction of the salt simulant in an autoclave with either zeolite 4A or sodium aluminate and colloidal silica. Chlorosodalite yields in the crystalline products were nearly complete in the glass-bonded materials at values of 100 mass% for the salt-occlusion method, up to 99.0 mass% for the hydrothermal synthesis with zeolite 4A, and up to 96 mass% for the hydrothermal synthesis with sodium aluminate and colloidal silica. These results show promise for using chemically stable chlorosodalite to immobilize oxide reduction salt wastes.

Hydrothermal carbonization of animal manures: Processes and energetics

USDA-ARS?s Scientific Manuscript database

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...

Hydrous partial melting in the sheeted dike complex at fast spreading ridges: experimental and natural observations

NASA Astrophysics Data System (ADS)

France, Lydéric; Koepke, Juergen; Ildefonse, Benoit; Cichy, Sarah B.; Deschamps, Fabien

2010-11-01

In ophiolites and in present-day oceanic crust formed at fast spreading ridges, oceanic plagiogranites are commonly observed at, or close to the base of the sheeted dike complex. They can be produced either by differentiation of mafic melts, or by hydrous partial melting of the hydrothermally altered sheeted dikes. In addition, the hydrothermally altered base of the sheeted dike complex, which is often infiltrated by plagiogranitic veins, is usually recrystallized into granoblastic dikes that are commonly interpreted as a result of prograde granulitic metamorphism. To test the anatectic origin of oceanic plagiogranites, we performed melting experiments on a natural hydrothermally altered dike, under conditions that match those prevailing at the base of the sheeted dike complex. All generated melts are water saturated, transitional between tholeiitic and calc-alkaline, and match the compositions of oceanic plagiogranites observed close to the base of the sheeted dike complex. Newly crystallized clinopyroxene and plagioclase have compositions that are characteristic of the same minerals in granoblastic dikes. Published silicic melt compositions obtained in classical MORB fractionation experiments also broadly match the compositions of oceanic plagiogranites; however, the compositions of the coexisting experimental minerals significantly deviate from those of the granoblastic dikes. Our results demonstrate that hydrous partial melting is a likely common process in the root zone of the sheeted dike complex, starting at temperatures exceeding 850°C. The newly formed melt can either crystallize to form oceanic plagiogranites or may be recycled within the melt lens resulting in hybridized and contaminated MORB melts. It represents the main MORB crustal contamination process. The residue after the partial melting event is represented by the granoblastic dikes. Our results support a model with a dynamic melt lens that has the potential to trigger hydrous partial melting reactions in the previously hydrothermally altered sheeted dikes. A new thermometer using the Al content of clinopyroxene is also elaborated.

Chemical environments of submarine hydrothermal systems

NASA Technical Reports Server (NTRS)

Shock, Everett L.

1992-01-01

Perhaps because black-smoker chimneys make tremendous subjects for magazine covers, the proposal that submarine hydrothermal systems were involved in the origin of life has caused many investigators to focus on the eye-catching hydrothermal vents. In much the same way that tourists rush to watch the spectacular eruptions of Old Faithful geyser with little regard for the hydrology of the Yellowstone basin, attention is focused on the spectacular, high-temperature hydrothermal vents to the near exclusion of the enormous underlying hydrothermal systems. Nevertheless, the magnitude and complexity of geologic structures, heat flow, and hydrologic parameters which characterize the geyser basins at Yellowstone also characterize submarine hydrothermal systems. However, in the submarine systems the scale can be considerably more vast. Like Old Faithful, submarine hydrothermal vents have a spectacular quality, but they are only one fascinating aspect of enormous geologic systems operating at seafloor spreading centers throughout all of the ocean basins. A critical study of the possible role of hydrothermal processes in the origin of life should include the full spectrum of probable environments. The goals of this chapter are to synthesize diverse information about the inorganic geochemistry of submarine hydrothermal systems, assemble a description of the fundamental physical and chemical attributes of these systems, and consider the implications of high-temperature, fluid-driven processes for organic synthesis. Information about submarine hydrothermal systems comes from many directions. Measurements made directly on venting fluids provide useful, but remarkably limited, clues about processes operating at depth. The oceanic crust has been drilled to approximately 2.0 km depth providing many other pieces of information, but drilling technology has not allowed the bore holes and core samples to reach the maximum depths to which aqueous fluids circulate in oceanic crust. Such determinations rely on studies of pieces of deep oceanic crust uplifted by tectonic forces such as along the Southwest Indian Ridge, or more complete sections of oceanic crust called ophiolite sequences which are presently exposed on continents owing to tectonic emplacement. Much of what is thought to happen in submarine hydrothermal systems is inferred from studies of ophiolite sequences, and especially from the better-exposed ophiolites in Oman, Cyprus and North America. The focus of much that follows is on a few general features: pressure, temperature, oxidation states, fluid composition and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

Spatially resolved sampling reveals dynamic microbial communities in rising hydrothermal plumes across a back-arc basin.

PubMed

Sheik, Cody S; Anantharaman, Karthik; Breier, John A; Sylvan, Jason B; Edwards, Katrina J; Dick, Gregory J

2015-06-01

Within hydrothermal plumes, chemosynthetic processes and microbe-mineral interactions drive primary productivity in deep-ocean food webs and may influence transport of elements such as iron. However, the source of microorganisms in plumes and the factors governing how these communities assemble are poorly understood, in part due to lack of data from early stages of plume formation. In this study, we examined microbial community composition of rising hydrothermal plumes from five vent fields along the Eastern Lau Spreading Center. Seafloor and plume microbial communities were significantly dissimilar and shared few phylotypes. Plume communities were highly similar to each other with significant differences in community membership only between Kilo Moana and Mariner, two vents that are separated by extremes in depth, latitude and geochemistry. Systematic sampling of waters surrounding the vents revealed that species richness and phylogenetic diversity was typically highest near the vent orifice, implying mixing of microbial communities from the surrounding habitats. Above-plume background communities were primarily dominated by SAR11, SAR324 and MG-I Archaea, while SUP05, Sulfurovum, Sulfurimonas, SAR324 and Alteromonas were abundant in plume and near-bottom background communities. These results show that the ubiquitous water-column microorganisms populate plume communities, and that the composition of background seawater exerts primary influence on plume community composition, with secondary influence from geochemical and/or physical properties of vents. Many of these pervasive deep-ocean organisms are capable of lithotrophy, suggesting that they are poised to use inorganic electron donors encountered in hydrothermal plumes.

Spatially resolved sampling reveals dynamic microbial communities in rising hydrothermal plumes across a back-arc basin

PubMed Central

Sheik, Cody S; Anantharaman, Karthik; Breier, John A; Sylvan, Jason B; Edwards, Katrina J; Dick, Gregory J

2015-01-01

Within hydrothermal plumes, chemosynthetic processes and microbe–mineral interactions drive primary productivity in deep-ocean food webs and may influence transport of elements such as iron. However, the source of microorganisms in plumes and the factors governing how these communities assemble are poorly understood, in part due to lack of data from early stages of plume formation. In this study, we examined microbial community composition of rising hydrothermal plumes from five vent fields along the Eastern Lau Spreading Center. Seafloor and plume microbial communities were significantly dissimilar and shared few phylotypes. Plume communities were highly similar to each other with significant differences in community membership only between Kilo Moana and Mariner, two vents that are separated by extremes in depth, latitude and geochemistry. Systematic sampling of waters surrounding the vents revealed that species richness and phylogenetic diversity was typically highest near the vent orifice, implying mixing of microbial communities from the surrounding habitats. Above-plume background communities were primarily dominated by SAR11, SAR324 and MG-I Archaea, while SUP05, Sulfurovum, Sulfurimonas, SAR324 and Alteromonas were abundant in plume and near-bottom background communities. These results show that the ubiquitous water-column microorganisms populate plume communities, and that the composition of background seawater exerts primary influence on plume community composition, with secondary influence from geochemical and/or physical properties of vents. Many of these pervasive deep-ocean organisms are capable of lithotrophy, suggesting that they are poised to use inorganic electron donors encountered in hydrothermal plumes. PMID:25489728

Enhanced performance of wearable piezoelectric nanogenerator fabricated by two-step hydrothermal process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu, Yu; Lei, Jixue; Yin, Bing

2014-03-17

A simple two-step hydrothermal process was proposed for enhancing the performance of the nanogenerator on flexible and wearable terylene-fabric substrate. With this method, a significant enhancement in output voltage of the nanogenerator from ∼10 mV to 7 V was achieved, comparing with the one by conventional one-step process. In addition, another advantage with the devices synthesized by two-step hydrothermal process was that their output voltages are only sensitive to strain rather than strain rate. The devices with a high output voltage have the ability to power common electric devices and will have important applications in flexible electronics and wearable devices.

Hydrothermal processes in the Edmond deposits, slow- to intermediate-spreading Central Indian Ridge

NASA Astrophysics Data System (ADS)

Cao, Hong; Sun, Zhilei; Zhai, Shikui; Cao, Zhimin; Jiang, Xuejun; Huang, Wei; Wang, Libo; Zhang, Xilin; He, Yongjun

2018-04-01

The Edmond hydrothermal field, located on the Central Indian Ridge (CIR), has a distinct mineralization history owing to its unique magmatic, tectonic, and alteration processes. Here, we report the detailed mineralogical and geochemical characteristics of hydrothermal metal sulfides recovered from this area. Based on the mineralogical investigations, the Edmond hydrothermal deposits comprise of high-temperature Fe-rich massive sulfides, medium-temperature Zn-rich sulfide chimney and low-temperature Ca-rich sulfate mineral assemblages. According to these compositions, three distinctive mineralization stages have been identified: (1) low-temperature consisting largely of anhydrite and pyrite/marcasite; (2) medium-high temperature distinguished by the mineral assemblage of pyrite, sphalerite and chalcopyrite; and (3) low-temperature stage characterized by the mineral assemblage of colloidal pyrite/marcasite, barite, quartz, anglesite. Several lines of evidence suggest that the sulfides were influenced by pervasive low-temperature diffuse flows in this area. The hydrothermal deposits are relatively enriched in Fe (5.99-18.93 wt%), Zn (2.10-10.00 wt%) and Ca (0.02-19.15 wt%), but display low Cu (0.28-0.81 wt%). The mineralogical varieties and low metal content of sulfides in the Edmond hydrothermal field both indicate that extensive water circulation is prevalent below the Edmond hydrothermal field. With regard to trace elements, the contents of Pb, Ba, Sr, As, Au, Ag, and Cd are significantly higher than those in other sediment-starved mid-ocean ridges, which is indicative of contribution from felsic rock sources. Furthermore, the multiphase hydrothermal activity and the pervasive water circulation underneath are speculated to play important roles in element remobilization and enrichment. Our findings deepen our understanding about the complex mineralization process in slow- to intermediate-spreading ridges globally.

Synthesis and hydrophobic adsorption properties of microporous/mesoporous hybrid materials.

PubMed

Hu, Qin; Li, Jinjun; Qiao, Shizhang; Hao, Zhengping; Tian, Hua; Ma, Chunyan; He, Chi

2009-05-30

Hybrid materials of silicalite-1 (Sil-1)-coated SBA-15 particles (MSs) have been successfully synthesized by crystallization process under hydrothermal conditions. These MSs materials were characterized by X-ray diffraction, nitrogen adsorption/desorption and TEM techniques, which illustrated that the silicalite-1-coated SBA-15 particles were successfully prepared and had large pore volume and hierarchical pore size distribution. Further experimental studies indicated that longer crystallization time under basic condition caused the mesostructure of SBA-15 materials to collapse destructively and higher calcination temperature tended to disrupt the long-range mesoscopic order while they had little influence on the phase of microcrystalline silicalite-1 zeolite. The resultant MSs materials were investigated by estimating dynamic adsorption capacity under dry and wet conditions to evaluate their adsorptive and hydrophobic properties. The hydrophobicity index (HI) value followed the sequence of silicalite-1>MSs>SBA-15, which revealed that the SBA-15 particles coated with the silicalite-1 seeds enhanced the surface hydrophobicity, and also were consistent with FTIR results. Our studies show that MSs materials combined the advantages of the ordered mesoporous material (high adsorptive capacity, large pore volume) and silicalite-1 zeolite (super-hydrophobic property, high hydrothermal stability), and the presence of micropores directly led to an increase in the dynamic adsorption capacity of benzene under dry and wet conditions.

Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors

PubMed Central

Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

2017-01-01

As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10–20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed. PMID:28291246

Layered double hydroxide using hydrothermal treatment: morphology evolution, intercalation and release kinetics of diclofenac sodium

NASA Astrophysics Data System (ADS)

Joy, Mathew; Iyengar, Srividhya J.; Chakraborty, Jui; Ghosh, Swapankumar

2017-12-01

The present work demonstrates the possibilities of hydrothermal transformation of Zn-Al layered double hydroxide (LDH) nanostructure by varying the synthetic conditions. The manipulation in washing step before hydrothermal treatment allows control over crystal morphologies, size and stability of their aqueous solutions. We examined the crystal growth process in the presence and the absence of extra ions during hydrothermal treatment and its dependence on the drug (diclofenac sodium (Dic-Na)) loading and release processes. Hexagonal plate-like crystals show sustained release with ˜90% of the drug from the matrix in a week, suggesting the applicability of LDH nanohybrids in sustained drug delivery systems. The fits to the release kinetics data indicated the drug release as a diffusion-controlled release process. LDH with rod-like morphology shows excellent colloidal stability in aqueous suspension, as studied by photon correlation spectroscopy.

Fundamental mechanisms and reactions in non-catalytic subcritical hydrothermal processes: A review.

PubMed

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

2017-10-15

The management and disposal of solid waste is of increasing concern across the globe. Hydrothermal processing of sludge has been suggested as a promising solution to deal with the considerable amounts of sludge produced worldwide. Such a process not only degrades organic compounds and reduces waste volume, but also provides an opportunity to recover valuable substances. Hydrothermal processing comprises two main sub-processes: wet oxidation (WO) and thermal hydrolysis (TH), in which the formation of various free radicals results in the production of different intermediates. Volatile fatty acids (VFAs), especially acetic acid, are usually the main intermediates which remain as a by-product of the process. This paper aims to review the fundamental mechanism for hydrothermal processing of sludge, and the formation of different free radicals and intermediates therein. In addition, the proposed kinetic models for the two processes (WO and TH) from the literature are reviewed and the advantages and disadvantages of each model are outlined. The effect of mass transfer as a critical component of the design and development of the processes, which has been neglected in most of these proposed models, is also reviewed, and the effect of influencing parameters on the processes' controlling step (reaction or mass transfer) is discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Using fumarolic inert gas composition to investigate magma dynamics at Campi Flegrei (Italy)

NASA Astrophysics Data System (ADS)

Chiodini, G.; Caliro, S.; Paonita, A.; Cardellini, C.

2013-12-01

Since 2000 the Campi Flegrei caldera sited in Neapolitan area (Italy), has showed signs of reactivation, marked by ground uplift, seismic activity, compositional variations of fumarolic effluents from La Solfatara, an increase of the fumarolic activity as well as of soil CO2 fluxes. Comparing long time series of geochemical signals with ground deformation and seismicity, we show that these changes are at least partially caused by repeated injections of magmatic fluid into the hydrothermal system. The frequency of these degassing episodes has increased in the last years, causing pulsed uplift episodes and swarms of low magnitude earthquakes. We focus here in the inert gas species (CO2-He-Ar-N2) of Solfatara fumaroles which displayed in the time spectacular and persistent variation trends affecting all the monitored vents. The observed variations, which include a continuous decrease of both N2/He and N2/CO2 ratios since 1985, paralleled by an increase of He/CO2, can not be explained neither with changes in processes of boiling-condensation in the local hydrothermal system nor with changes in the mixing proportions between a magmatic vapour and hydrothermal fluids. Consequently we investigated the possibility that the trends of inert gas species are governed by changes in the conditions controlling magma degassing at depth. We applied a magma degassing model, with the most recent updates for inert gas solubilities, after to have included petrologic constraints from the ranges of melt composition and reservoir pressure at Campi Flegrei. The model simulations for mafic melts (trachybasalt and shoshonite) show a surprising agreement with the measured data. Both decompressive degassing of an ascending magma and mixing between magmatic fluids exsolved at various levels along the ascent path can explain the long-time geochemical changes. Our work highlights that, in caldera systems where the presence of hydrothermal aquifers commonly masks the magmatic signature of reactive volatiles, inert gases are the preferred species to achieve information on the dynamics and structure of the magma plumbing systems.

Micro-seismic earthquakes characteristics at natural and exploited hydrothermal systems in West Java, Indonesia

NASA Astrophysics Data System (ADS)

Jousset, P. G.; Jaya, M. S.; Sule, R.; Diningrat, W.; Gassner, A.; Akbar, F.; Ryannugroho, R.; Hendryana, A.; Kusnadi, Y.; Syahbana, D.; Nugraha, A. D.; Umar, M.; Indrinanto, Y.; Erbas, K.

2013-12-01

The assessment of geothermal resources requires the understanding of the structure and the dynamics of geothermal reservoirs. We deployed a multidisciplinary geophysical network around geothermal areas in the south of Bandung, West Java, Indonesia. The first deployment included a network of 30 broadband and 4 short-period seismic stations with Güralp and Trillium sensors (0.008 - 100 Hz) since October 2012. In a second step, we extended the network in June 2013 with 16 short-period (1 Hz) seismometers. We describe the set-up of the seismic networks and discuss first observations and results. The co-existence of a large variety of intense surface manifestations like geysers, hot-steaming grounds, hot water pools, and active volcanoes suggest an intimate coupling between volcanic, tectonic and hydrothermal processes in this area. Preliminary location of earthquakes is performed using a non-linear algorithm, which allows us to define at least 3 seismic clusters. We discuss this seismic pattern within the geothermal fields.

Hydrothermal treatment followed by enzymatic hydrolysis and hydrothermal carbonization as means to valorise agro- and forest-based biomass residues.

PubMed

Wikberg, Hanne; Grönqvist, Stina; Niemi, Piritta; Mikkelson, Atte; Siika-Aho, Matti; Kanerva, Heimo; Käsper, Andres; Tamminen, Tarja

2017-07-01

The suitability of several abundant but underutilized agro and forest based biomass residues for hydrothermal treatment followed by enzymatic hydrolysis as well as for hydrothermal carbonization was studied. The selected approaches represent simple biotechnical and thermochemical treatment routes suitable for wet biomass. Based on the results, the hydrothermal pre-treatment followed by enzymatic hydrolysis seemed to be most suitable for processing of carbohydrate rich corn leaves, corn stover, wheat straw and willow. High content of thermally stable components (i.e. lignin) and low content of ash in the biomass were advantageous for hydrothermal carbonization of grape pomace, coffee cake, Scots pine bark and willow. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Growth of Berlinite (AlPO4) Single Crystals.

DTIC Science & Technology

1980-03-01

Solubility of AlPO 4 18 6. Solubility Data of Jahn and Kordes on AlPO4 19 7. AlPO 4 Seed Crystal 23 8. Tem-Pres Hydrothermal Research Unit 25 9...Since the vapor pressure of water rises rapidly with temperature, a closed hydrothermal system was used. In a seeded hydrothermal growth process, the...to investigate the hydrothermal growth of Berlinite (AlPO4 ) to determine the optimum growth conditions for large high quality crystals. Over thirty

Impact of hydrothermalism on the ocean iron cycle

PubMed Central

Resing, Joseph

2016-01-01

As the iron supplied from hydrothermalism is ultimately ventilated in the iron-limited Southern Ocean, it plays an important role in the ocean biological carbon pump. We deploy a set of focused sensitivity experiments with a state of the art global model of the ocean to examine the processes that regulate the lifetime of hydrothermal iron and the role of different ridge systems in governing the hydrothermal impact on the Southern Ocean biological carbon pump. Using GEOTRACES section data, we find that stabilization of hydrothermal iron is important in some, but not all regions. The impact on the Southern Ocean biological carbon pump is dominated by poorly explored southern ridge systems, highlighting the need for future exploration in this region. We find inter-basin differences in the isopycnal layer onto which hydrothermal Fe is supplied between the Atlantic and Pacific basins, which when combined with the inter-basin contrasts in oxidation kinetics suggests a muted influence of Atlantic ridges on the Southern Ocean biological carbon pump. Ultimately, we present a range of processes, operating at distinct scales, that must be better constrained to improve our understanding of how hydrothermalism affects the ocean cycling of iron and carbon. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035256

Impact of hydrothermalism on the ocean iron cycle.

PubMed

Tagliabue, Alessandro; Resing, Joseph

2016-11-28

As the iron supplied from hydrothermalism is ultimately ventilated in the iron-limited Southern Ocean, it plays an important role in the ocean biological carbon pump. We deploy a set of focused sensitivity experiments with a state of the art global model of the ocean to examine the processes that regulate the lifetime of hydrothermal iron and the role of different ridge systems in governing the hydrothermal impact on the Southern Ocean biological carbon pump. Using GEOTRACES section data, we find that stabilization of hydrothermal iron is important in some, but not all regions. The impact on the Southern Ocean biological carbon pump is dominated by poorly explored southern ridge systems, highlighting the need for future exploration in this region. We find inter-basin differences in the isopycnal layer onto which hydrothermal Fe is supplied between the Atlantic and Pacific basins, which when combined with the inter-basin contrasts in oxidation kinetics suggests a muted influence of Atlantic ridges on the Southern Ocean biological carbon pump. Ultimately, we present a range of processes, operating at distinct scales, that must be better constrained to improve our understanding of how hydrothermalism affects the ocean cycling of iron and carbon.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2016 The Author(s).

Sulfur Metabolizing Microbes Dominate Microbial Communities in Andesite-Hosted Shallow-Sea Hydrothermal Systems

PubMed Central

Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

2012-01-01

To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan’s coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH4) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH4 was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH4 concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan. PMID:22970260

Sulfur metabolizing microbes dominate microbial communities in Andesite-hosted shallow-sea hydrothermal systems.

PubMed

Zhang, Yao; Zhao, Zihao; Chen, Chen-Tung Arthur; Tang, Kai; Su, Jianqiang; Jiao, Nianzhi

2012-01-01

To determine microbial community composition, community spatial structure and possible key microbial processes in the shallow-sea hydrothermal vent systems off NE Taiwan's coast, we examined the bacterial and archaeal communities of four samples collected from the water column extending over a redoxocline gradient of a yellow and four from a white hydrothermal vent. Ribosomal tag pyrosequencing based on DNA and RNA showed statistically significant differences between the bacterial and archaeal communities of the different hydrothermal plumes. The bacterial and archaeal communities from the white hydrothermal plume were dominated by sulfur-reducing Nautilia and Thermococcus, whereas the yellow hydrothermal plume and the surface water were dominated by sulfide-oxidizing Thiomicrospira and Euryarchaeota Marine Group II, respectively. Canonical correspondence analyses indicate that methane (CH(4)) concentration was the only statistically significant variable that explains all community cluster patterns. However, the results of pyrosequencing showed an essential absence of methanogens and methanotrophs at the two vent fields, suggesting that CH(4) was less tied to microbial processes in this shallow-sea hydrothermal system. We speculated that mixing between hydrothermal fluids and the sea or meteoric water leads to distinctly different CH(4) concentrations and redox niches between the yellow and white vents, consequently influencing the distribution patterns of the free-living Bacteria and Archaea. We concluded that sulfur-reducing and sulfide-oxidizing chemolithoautotrophs accounted for most of the primary biomass synthesis and that microbial sulfur metabolism fueled microbial energy flow and element cycling in the shallow hydrothermal systems off the coast of NE Taiwan.

Internal structure and volcanic hazard potential of Mt Tongariro, New Zealand, from 3D gravity and magnetic models

NASA Astrophysics Data System (ADS)

Miller, Craig A.; Williams-Jones, Glyn

2016-06-01

A new 3D geophysical model of the Mt Tongariro Volcanic Massif (TgVM), New Zealand, provides a high resolution view of the volcano's internal structure and hydrothermal system, from which we derive implications for volcanic hazards. Geologically constrained 3D inversions of potential field data provides a greater level of insight into the volcanic structure than is possible from unconstrained models. A complex region of gravity highs and lows (± 6 mGal) is set within a broader, 20 mGal gravity low. A magnetic high (1300 nT) is associated with Mt Ngauruhoe, while a substantial, thick, demagnetised area occurs to the north, coincident with a gravity low and interpreted as representing the hydrothermal system. The hydrothermal system is constrained to the west by major faults, interpreted as an impermeable barrier to fluid migration and extends to basement depth. These faults are considered low probability areas for future eruption sites, as there is little to indicate they have acted as magmatic pathways. Where the hydrothermal system coincides with steep topographic slopes, an increased likelihood of landslides is present and the newly delineated hydrothermal system maps the area most likely to have phreatic eruptions. Such eruptions, while small on a global scale, are important hazards at the TgVM as it is a popular hiking area with hundreds of visitors per day in close proximity to eruption sites. The model shows that the volume of volcanic material erupted over the lifespan of the TgVM is five to six times greater than previous estimates, suggesting a higher rate of magma supply, in line with global rates of andesite production. We suggest that our model of physical property distribution can be used to provide constraints for other models of dynamic geophysical processes occurring at the TgVM.

Hydrothermal variations in soils resulting from the freezing and thawing processes in the active layer of an alpine grassland in the Qilian Mountains, northeastern Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wang, Qingfeng; Yang, Qianqian; Guo, Hong; Xiao, Xiongxin; Jin, Huijun; Li, Lili; Zhang, Tingjun; Wu, Qingbai

2018-06-01

Soil hydrothermal dynamics, resulting from the freezing and thawing processes in the active layer and their influencing factors, were studied in the upper Heihe River Basin (UHRB) in the Qilian Mountains, northeastern Tibetan Plateau. Soil temperature and water content measurements were taken in the active layer of the UHRB in alpine grassland from 2013 to 2014. The results showed that the thaw rate of the active layer was significantly smaller in alpine paludal meadows than the thaw rate in alpine meadows and alpine steppes. This was mainly related to the hydrothermal properties of soils in the active layer, such as moisture content, thermal conductivity, and specific heat. During the thawing process, the active layer soil water content was higher and fluctuated less in alpine paludal meadows. Conversely, the soil water content was lower and fluctuated more significantly in alpine meadows and alpine steppes. These findings could be explained by the prevalence of peat soils, with a low bulk density, and high clay and organic matter content. By contrast, the soil particles in the active layer of alpine meadows and alpine steppes were significantly coarser, with higher bulk density and lower organic matter content. During the freezing process, gravel content and soil texture had a great impact on the unfrozen water content in the frozen soils. However, the factors influencing the soil water retention in frozen soils are complex, and further study is needed. These results provide theoretical support for the evaluation of the hydrological characteristics of the alpine permafrost zone in the Qilian Mountains. Furthermore, the effect of frozen ground on hydrological changes due to climate change in the Heihe River Basin can be simulated and predicted, providing a scientific basis for the ecological conservation of the Qilian Mountains National Park.

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

USDA-ARS?s Scientific Manuscript database

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...

Hydrothermal systems are a sink for dissolved black carbon in the deep ocean

NASA Astrophysics Data System (ADS)

Niggemann, J.; Hawkes, J. A.; Rossel, P. E.; Stubbins, A.; Dittmar, T.

2016-02-01

Exposure to heat during fires on land or geothermal processes in Earth's crust induces modifications in the molecular structure of organic matter. The products of this thermogenesis are collectively termed black carbon. Dissolved black carbon (DBC) is a significant component of the oceanic dissolved organic carbon (DOC) pool. In the deep ocean, DBC accounts for 2% of DOC and has an apparent radiocarbon age of 18,000 years. Thus, DBC is much older than the bulk DOC pool, suggesting that DBC is highly refractory. Recently, it has been shown that recalcitrant deep-ocean DOC is efficiently removed during hydrothermal circulation. Here, we hypothesize that hydrothermal circulation is also a net sink for deep ocean DBC. We analyzed DBC in samples collected at different vent sites in the Atlantic, Pacific and Southern oceans. DBC was quantified in solid-phase extracts as benzenepolycarboxylic acids (BPCAs) following nitric acid digestion. Concentrations of DBC were much lower in hydrothermal fluids than in surrounding deep ocean seawater, confirming that hydrothermal circulation acts as a net sink for oceanic DBC. The relative contribution of DBC to bulk DOC did not change during hydrothermal circulation, indicating that DBC is removed at similar rates as bulk DOC. The ratio of the oxidation products benzenehexacarboxylic acid (B6CA) to benzenepentacarboxylic acid (B5CA) was significantly higher in hydrothermally altered samples compared to ratios typically found in the deep ocean, reflecting a higher degree of condensation of DBC molecules after hydrothermal circulation. Our study identified hydrothermal circulation as a quantitatively important sink for refractory DBC in the deep ocean. In contrast to photodegradation of DBC at the sea surface, which is more efficient for more condensed DBC, i.e. decreasing the B6CA/B5CA ratio, hydrothermal processing increases the B6CA/B5CA ratio, introducing a characteristic hydrothermal DBC signature.

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.

Characterization of Particles Created By Laser-Driven Hydrothermal Processing

DTIC Science & Technology

2016-06-01

created by laser-driven hydrothermal processing, an innovative technique used for the ablation of submerged materials. Two naturally occurring...processing, characterization, obsidian, tektite, natural glass 15. NUMBER OF PAGES 89 16. PRICE CODE 17. SECURITY CLASSIFICATION OF REPORT...technique used for the ablation of submerged materials. Two naturally occurring materials, obsidian and tektite, were used as targets for this technique

Intelligent Processing of Ferroelectric Thin Films

DTIC Science & Technology

1993-09-03

the acetate precursors. The results from these experiments involving coprecipitation, hydrothermal , spray pyrolysis and freeze drying have shown that...Spray Pyrolysis (SP) D. Hydrothermal Processing (HP) The powder produced by each process was characterized by X-ray diffraction (XRD) and scanning...precursors were used as described above. Instead of ammonia solution, an oxalic acid solution was used as the3 precipitating agent. The precipitants

Marine Subsurface Microbial Community Shifts Across a Hydrothermal Gradient in Okinawa Trough Sediments

PubMed Central

2016-01-01

Sediments within the Okinawa back-arc basin overlay a subsurface hydrothermal network, creating intense temperature gradients with sediment depth and potential limits for microbial diversity. We investigated taxonomic changes across 45 m of recovered core with a temperature gradient of 3°C/m from the dynamic Iheya North Hydrothermal System. The interval transitions sharply from low-temperature marine mud to hydrothermally altered clay at 10 meters below seafloor (mbsf). Here, we present taxonomic results from an analysis of the 16S rRNA gene that support a conceptual model in which common marine subsurface taxa persist into the subsurface, while high temperature adapted archaeal taxa show localized peaks in abundances in the hydrothermal clay horizons. Specifically, the bacterial phylum Chloroflexi accounts for a major proportion of the total microbial community within the upper 10 mbsf, whereas high temperature archaea (Terrestrial Hot Spring Crenarchaeotic Group and methanotrophic archaea) appear in varying local abundances in deeper, hydrothermal clay horizons with higher in situ temperatures (up to 55°C, 15 mbsf). In addition, geochemical evidence suggests that methanotrophy may be occurring in various horizons. There is also relict DNA (i.e., DNA preserved after cell death) that persists in horizons where the conditions suitable for microbial communities have ceased. PMID:28096736

High-pressure homogenization associated hydrothermal process of palygorskite for enhanced adsorption of Methylene blue

NASA Astrophysics Data System (ADS)

Zhang, Zhifang; Wang, Wenbo; Wang, Aiqin

2015-02-01

Palygorskite (PAL) was modified by a high-pressure homogenization assisted hydrothermal process. The effects of modification on the morphology, structure and physicochemical properties of PAL were systematically investigated by Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD) and Zeta potential analysis techniques, and the adsorption properties were systematically evaluated using Methylene blue (MB) as the model dye. The results revealed that the crystal bundles were disaggregated and the PAL nanorods became more even after treated via associated high-pressure homogenization and hydrothermal process, and the crystal bundles were dispersed as nanorods. The intrinsic crystal structure of PAL was remained after hydrothermal treatment, and the pore size calculated by the BET method was increased. The adsorption properties of PAL for MB were evidently improved (from 119 mg/g to 171 mg/g) after modification, and the dispersion of PAL before hydrothermal reaction is favorable to the adsorption. The desorption evaluation confirms that the modified PAL has stronger affinity with MB, which is benefit to fabricate a stable organic-inorganic hybrid pigment.

Immobilization of LiCl-Li 2 O pyroprocessing salt wastes in chlorosodalite using glass-bonded hydrothermal and salt-occlusion methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riley, Brian J.; Peterson, Jacob A.; Kroll, Jared O.

In this study, salt occlusion and hydrothermal processes were used to make chlorosodalite through reaction with a high-LiCl salt simulating a waste stream following pyrochemical treatment of oxide-based used nuclear fuel. Some products were reacted with glass binders to increase chlorosodalite yield through alkali ion exchange and aide in densification. Hydrothermal processes included reaction of the salt simulant in an acid digestion vessel with either zeolite 4A or sodium aluminate and colloidal silica. Chlorosodalite yields in the crystalline products were nearly complete in the glass-bonded materials at values of 100 mass% for the salt-occlusion method, up to 99.0 mass% formore » the hydrothermal synthesis with zeolite 4A, and up to 96 mass% for the hydrothermal synthesis with sodium aluminate and colloidal silica. These results show promise for using chemically stable chlorosodalite to immobilize oxide reduction salt wastes.« less

Improvement in the productivity of xylooligosaccharides from waste medium after mushroom cultivation by hydrothermal treatment with suitable pretreatment.

PubMed

Sato, Nobuaki; Shinji, Kazunori; Mizuno, Masahiro; Nozaki, Kouichi; Suzuki, Masayuki; Makishima, Satoshi; Shiroishi, Masahiro; Onoda, Takeru; Takahashi, Fumihiro; Kanda, Takahisa; Amano, Yoshihiko

2010-08-01

The effective xylooligosaccharides (XOs) production from the waste medium after mushroom cultivation (WM) was investigated. The WM contains rich nutrients (protein, etc.) which induce Maillard reaction with reducing sugars under hydrothermal conditions. To improve the productivity of XOs, the suitable pretreatment combined with washing and grinding was investigated, and subsequently hydrothermal treatment was demonstrated with batch type and continuous flow type reactor. The washing pretreatment with hot water of 60 degrees C was effective to remove nutrients from the WM, and it led to prevent brownish discoloration on the hydrothermal treatment. On the basis of experimental data, industrial XOs production processes consisting of the pretreatment, hydrothermal treatment and purification step was designed. During the designed process, 2.3 kg-dry of the purified XOs was produced from 30 kg-wet of the WM (15% yield as dry basis weight). Theoretical yield of XOs attained to 48% as xylan weight in the WM. (c) 2010 Elsevier Ltd. All rights reserved.

Characterizing the dynamics of hydrothermal systems with muon tomography: the case of La Soufrière de Guadeloupe

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, M.; Marteau, J.; Tramontini, M.; de Bremond d Ars, J.; Le Gonidec, Y.; Carlus, B.; Ianigro, J. C.; Deroussi, S.; Komorowski, J. C.; Gibert, D.

2017-12-01

Muon imaging has recently emerged as a powerful method to complement standard geophysical tools in the study of the Earth's subsurface. Muon measurements yield a radiography of the average density along the muon path, allowing to image large volumes of a geological body from a single observation point. Long-term measurements allow to infer density changes by tracking the associated variations in the muon flux. In the context of volcanic hydrothermal systems, this approach helps to characterize zones of steam formation, condensation, water infiltration and storage. We present results of imaging the La Soufrière de Guadeloupe dome and shallow active hydrothermal system with a network of muon telescopes viewing the dome from different positions around its base. First, we jointly invert the muon radiographies of the different telescopes with gravity data to obtain a three-dimensional density model of the lava dome. The model reveals an extended low density region where the hydrothermal system is most active. We then analyze the dynamics of the hydrothermal system from long-term measurements (more than 2 years of almost non-interrupted acquisition) with 5 simultaneous muon telescopes. We identify a periodicity of 1-2 months in the density increase/decrease in the most active zones below fumaroles and acid boiling ponds. Our simultaneous-muon telescope strategy provides constraints on the three-dimensional location of the density changes and an improved quantification of the associated mass flux changes. We compare the temporal trends acquired by the different muon telescopes to time-series of rainfall on the summit recharge area as well as to ground temperature profiles in the vicinity of thermal anomalies and high-discharge summit fumaroles.

Lithium isotopic systematics of submarine vent fluids from arc and back-arc hydrothermal systems in the western Pacific

NASA Astrophysics Data System (ADS)

Araoka, Daisuke; Nishio, Yoshiro; Gamo, Toshitaka; Yamaoka, Kyoko; Kawahata, Hodaka

2016-10-01

The Li concentration and isotopic composition (δ7Li) in submarine vent fluids are important for oceanic Li budget and potentially useful for investigating hydrothermal systems deep under the seafloor because hydrothermal vent fluids are highly enriched in Li relative to seawater. Although Li isotopic geochemistry has been studied at mid-ocean-ridge (MOR) hydrothermal sites, in arc and back-arc settings Li isotopic composition has not been systematically investigated. Here we determined the δ7Li and 87Sr/86Sr values of 11 end-member fluids from 5 arc and back-arc hydrothermal systems in the western Pacific and examined Li behavior during high-temperature water-rock interactions in different geological settings. In sediment-starved hydrothermal systems (Manus Basin, Izu-Bonin Arc, Mariana Trough, and North Fiji Basin), the Li concentrations (0.23-1.30 mmol/kg) and δ7Li values (+4.3‰ to +7.2‰) of the end-member fluids are explained mainly by dissolution-precipitation model during high-temperature seawater-rock interactions at steady state. Low Li concentrations are attributable to temperature-related apportioning of Li in rock into the fluid phase and phase separation process. Small variation in Li among MOR sites is probably caused by low-temperature alteration process by diffusive hydrothermal fluids under the seafloor. In contrast, the highest Li concentrations (3.40-5.98 mmol/kg) and lowest δ7Li values (+1.6‰ to +2.4‰) of end-member fluids from the Okinawa Trough demonstrate that the Li is predominantly derived from marine sediments. The variation of Li in sediment-hosted sites can be explained by the differences in degree of hydrothermal fluid-sediment interactions associated with the thickness of the marine sediment overlying these hydrothermal sites.

Contrasted hydrothermal activity along the South-East Indian Ridge (130°E-140°E): From crustal to ultramafic circulation

NASA Astrophysics Data System (ADS)

Boulart, Cédric; Briais, Anne; Chavagnac, Valérie; Révillon, Sidonie; Ceuleneer, Georges; Donval, Jean-Pierre; Guyader, Vivien; Barrere, Fabienne; Ferreira, Nicolas; Hanan, Barry; Hémond, Christophe; Macleod, Sarah; Maia, Marcia; Maillard, Agnès.; Merkuryev, Sergey; Park, Sung-Hyun; Ruellan, Etienne; Schohn, Alexandre; Watson, Sally; Yang, Yun-Seok

2017-07-01

Using a combined approach of seafloor mapping, MAPR and CTD survey, we report evidence for active hydrothermal venting along the 130°-140°E section of the poorly-known South-East Indian Ridge (SEIR) from the Australia-Antarctic Discordance (AAD) to the George V Fracture Zone (FZ). Along the latter, we report Eh and CH4 anomalies in the water column above a serpentinite massif, which unambiguously testify for ultramafic-related fluid flow. This is the first time that such circulation is observed on an intermediate-spreading ridge. The ridge axis itself is characterized by numerous off-axis volcanoes, suggesting a high magma supply. The water column survey indicates the presence of at least ten distinct hydrothermal plumes along the axis. The CH4:Mn ratios of the plumes vary from 0.37 to 0.65 denoting different underlying processes, from typical basalt-hosted to ultramafic-hosted high-temperature hydrothermal circulation. Our data suggest that the change of mantle temperature along the SEIR not only regulates the magma supply, but also the hydrothermal activity. The distribution of hydrothermal plumes from a ridge segment to another implies secondary controls such as the presence of fractures and faults along the axis or in the axial discontinuities. We conclude from these results that hydrothermal activity along the SEIR is controlled by magmatic processes at the regional scale and by the tectonics at the segment scale, which influences the type of hydrothermal circulation and leads to various chemical compositions. Such variety may impact global biogeochemical cycles, especially in the Southern Ocean where hydrothermal venting might be the only source of nutrients.

The hydrothermal evolution of the Kawerau geothermal system, New Zealand

NASA Astrophysics Data System (ADS)

Milicich, S. D.; Chambefort, I.; Wilson, C. J. N.; Charlier, B. L. A.; Tepley, F. J.

2018-03-01

Hydrothermal alteration zoning and processes provide insights into the evolution of heat source(s) and fluid compositions associated with geothermal systems. Traditional petrological techniques, combined with hydrothermal alteration studies, stable isotope analyses and geochronology can resolve the nature of the fluids involved in hydrothermal processes and their changes through time. We report here new findings along with previous unpublished works on alteration patterns, fluid inclusion measurements and stable isotope data to provide insights into the thermal and chemical evolution of the Kawerau geothermal system, New Zealand. These data indicate the presence of two hydrothermal events that can be coupled with chronological data. The earlier period of hydrothermal activity was initiated at 400 ka, with the heat driving the hydrothermal system inferred to be from the magmatic system that gave rise to rhyolite lavas and sills of the Caxton Formation. Isotopic data fingerprint fluids attributed to this event as meteoric, indicating that the magma primarily served as a heat source driving fluid circulation, and was not releasing magmatic fluids in sufficient quantity to affect the rock mineralogy and thus inferred fluid compositions. The modern Kawerau system was initiated at 16 ka with hydrothermal eruptions linked to shallow intrusion of magma at the onset of activity that gave rise to the Putauaki andesite cone. Likely associated with this later event was a pulse of magmatic CO2, resulting in large-scale deposition of hydrothermal calcite enriched in 18O. Meteoric water-dominated fluids subsequently overwhelmed the magmatic fluids associated with this 18O-rich signature, and both the fluid inclusion microthermometry and stable isotope data reflect a change to the present-day fluid chemistry of low salinity, meteoric-dominated waters.

Catastrophic volcanic collapse: relation to hydrothermal processes.

PubMed

López, D L; Williams, S N

1993-06-18

Catastrophic volcanic collapse, without precursory magmatic activity, is characteristic of many volcanic disasters. The extent and locations of hydrothermal discharges at Nevado del Ruiz volcano, Colombia, suggest that at many volcanoes collapse may result from the interactions between hydrothermal fluids and the volcanic edifice. Rock dissolution and hydrothermal mineral alteration, combined with physical triggers such as earth-quakes, can produce volcanic collapse. Hot spring water compositions, residence times, and flow paths through faults were used to model potential collapse at Ruiz. Caldera dimensions, deposits, and alteration mineral volumes are consistent with parameters observed at other volcanoes.

Hydrothermal synthesis of thiol-capped CdTe nanoparticles and their optical properties.

PubMed

Bu, Hang-Beom; Kikunaga, Hayato; Shimura, Kunio; Takahasi, Kohji; Taniguchi, Taichi; Kim, DaeGwi

2013-02-28

Water soluble nanoparticles (NPs) with a high emission property were synthesized via hydrothermal routes. In this report, we chose thiol ligand N-acetyl-L-cysteine as the ideal stabilizer and have successfully employed it to synthesize readily size-controllable CdTe NPs in a reaction of only one step. Hydrothermal synthesis of CdTe NPs has been carried out in neutral or basic conditions so far. We found out that the pH value of precursor solutions plays an important role in the uniformity of the particle size. Actually, high quality CdTe NPs were synthesized under mild acidic conditions of pH 5. The resultant NPs indicated good visible light-emitting properties and stability. Further, the experimental results showed that the reaction temperature influenced significantly the growth rate and the maximum size of the NPs. The CdTe NPs with a high photoluminescence quantum yield (the highest value: 57%) and narrower half width at half maximum (the narrowest value: 33 nm) were attained in very short time, within 40 minutes, reaching diameters of 2.3 to 4.3 nm. The PL intensity was increased with an increase in the reaction time, reflecting the suppression of nonradiative recombination processes. Furthermore, the formation of CdTe/CdS core-shell structures was discussed from the viewpoint of PL dynamics and X-ray diffraction studies.

Dynamics of cell proliferation and apoptosis reflect different life strategies in hydrothermal vent and cold seep vestimentiferan tubeworms.

PubMed

Pflugfelder, Bettina; Cary, S Craig; Bright, Monika

2009-07-01

Deep-sea vestimentiferan tubeworms, which live in symbiosis with bacteria, exhibit different life strategies according to their habitat. At unstable and relatively short-lived hydrothermal vents, they grow extremely fast, whereas their close relatives at stable and long-persisting cold seeps grow slowly and live up to 300 years. Growth and age differences are thought to occur because of ecological and physiological adaptations. However, the underlying mechanisms of cell proliferation and death, which are closely linked to homeostasis, growth, and longevity, are unknown. Here, we show by immunohistochemical and ultrastructural cell cycle analyses that cell proliferation activities of the two species studied are higher than in any other characterized invertebrate, being only comparable with tumor and wound-healing processes. The slow growth in Lamellibrachia luymesi from cold seeps results from balanced activities of proliferation and apoptosis in the epidermis. In contrast, Riftia pachyptila from hydrothermal vents grows fast because apoptosis is down-regulated in this tissue. The symbiont-housing organ, the trophosome, exhibits a complex cell cycle and terminal differentiation pattern in both species, and growth is regulated by proliferation. These mechanisms have similarities to the up- and down-regulation of proliferation or apoptosis in various types of tumor, although they occur in healthy animals in this study, thus providing significant insights into the underlying mechanisms of growth and longevity.

One-step process of hydrothermal and alkaline treatment of wheat straw for improving the enzymatic saccharification.

PubMed

Sun, Shaolong; Zhang, Lidan; Liu, Fang; Fan, Xiaolin; Sun, Run-Cang

2018-01-01

To increase the production of bioethanol, a two-step process based on hydrothermal and dilute alkaline treatment was applied to reduce the natural resistance of biomass. However, the process required a large amount of water and a long operation time due to the solid/liquid separation before the alkaline treatment, which led to decrease the pure economic profit for production of bioethanol. Therefore, four one-step processes based on order of hydrothermal and alkaline treatment have been developed to enhance concentration of glucose of wheat straw by enzymatic saccharification. The aim of the present study was to systematically evaluated effect for different one-step processes by analyzing the physicochemical properties (composition, structural change, crystallinity, surface morphology, and BET surface area) and enzymatic saccharification of the treated substrates. In this study, hemicelluloses and lignins were removed from wheat straw and the morphologic structures were destroyed to various extents during the four one-step processes, which were favorable for cellulase absorption on cellulose. A positive correlation was also observed between the crystallinity and enzymatic saccharification rate of the substrate under the conditions given. The surface area of the substrate was positively related to the concentration of glucose in this study. As compared to the control (3.0 g/L) and treated substrates (11.2-14.6 g/L) obtained by the other three one-step processes, the substrate treated by one-step process based on successively hydrothermal and alkaline treatment had a maximum glucose concentration of 18.6 g/L, which was due to the high cellulose concentration and surface area for the substrate, accompanying with removal of large amounts of lignins and hemicelluloses. The present study demonstrated that the order of hydrothermal and alkaline treatment had significant effects on the physicochemical properties and enzymatic saccharification of wheat straw. The one-step process based on successively hydrothermal and alkaline treatment is a simple operating and economical feasible method for the production of glucose, which will be further converted into bioethanol.

Exceptional discovery of a shallow-water hydrothermal site in the SW area of Basiluzzo islet (Aeolian archipelago, South Tyrrhenian Sea): An environment to preserve.

PubMed

Esposito, Valentina; Andaloro, Franco; Canese, Simonepietro; Bortoluzzi, Giovanni; Bo, Marzia; Di Bella, Marcella; Italiano, Francesco; Sabatino, Giuseppe; Battaglia, Pietro; Consoli, Pierpaolo; Giordano, Patrizia; Spagnoli, Federico; La Cono, Violetta; Yakimov, Michail M; Scotti, Gianfranco; Romeo, Teresa

2018-01-01

The geological, biological and geochemical features of a particular field of hydrothermal vents, discovered in the Panarea Volcanic Complex during a research survey carried out in 2015, are described for the first time. The site, located at 70-80 m depth off the South-western coast of the islet of Basiluzzo, was named Smoking Land for the presence of a large number of wide and high active chimneys and was characterized in terms of dissolved benthic fluxes, associated macrofauna and megafauna communities and preliminary mineralogy and geochemistry of chimney structures. On the whole field, a total of 39 chimneys, different in size and shape, were closely observed and described; 14 of them showed emission of low temperature hydrothermal fluids of marine origin characterized by acidified chemical conditions. The CTD and benthic chamber measurements highlighted that the Smoking Land is able to form a sea water bottom layer characterized by variable acidity and high DIC and trace elements concentrations; these characteristics weaken moving away from the chimney mouths. The SEM-EDS analysis of the collected solid samples revealed a chimney structure principally composed by amorphous and low crystalline Fe-oxyhydroxides of hydrothermal origins. The ROV explorations revealed a wide coverage of red algae (Peyssonnelia spp.) colonized by the green algae Flabiella petiolata and by suspension feeders, mainly sponges, but also bryozoans, and tubicolous polychaetes. Although novent-exclusive species were identified, the benthic communities found in association to the chimneys included more taxa than those observed in the surrounding no-vent rocky areas. These first findings evidence a submarine dynamic habitat where geological, chemical and biological processes are intimately connected, making the Smoking Land an important site in terms of marine heritage that should be safeguarded and protected.

The effect of urea on microstructures of tin dioxide grown on Ti plate and its supercapacitor performance

NASA Astrophysics Data System (ADS)

Jinlong, Lv; Meng, Yang; Miura, Hideo

2017-02-01

The effects of urea on microstructures of SnO2 during hydrothermal process and its supercapacitor performance were investigated. The sphere SnO2 was formed on Ti plate in hydrothermal solution without urea, while the SnO2 micro-flowers were assembled by numerous few-layered nanopetals due to adding to urea during hydrothermal process. The separated SnO2 nanopetals arrays showed better electrochemical performance than sphere SnO2. The gap between SnO2 nanopetals promoted penetration of the electrolyte and induced high supercapacitive performance.

Tourmaline as a recorder of ore-forming processes

USGS Publications Warehouse

Slack, John F.; Trumbull, Robert B.

2011-01-01

Tourmaline occurs in diverse types of hydrothermal mineral deposits and can be used to constrain the nature and evolution of ore-forming fl uids. Because of its broad range in composition and retention of chemical and isotopic signatures, tourmaline may be the only robust recorder of original mineralizing processes in some deposits. Microtextures and in situ analysis of compositional and isotopic variations in ore-related tourmaline provide valuable insights into hydrothermal systems in seafl oor, sedimentary, magmatic, and metamorphic environments. Deciphering the hydrothermal record in tourmaline also holds promise for aiding exploration programs in the search for new ore deposits.

Ion dynamics in nanocrystalline LiMnPO{sub 4} synthesised by novel template free hydrothermal approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, Lakshmi, E-mail: lakshmivijayan@gmail.com; Cheruku, Rajesh; Govindaraj, G.

A dense core rectangular shaped nanocrystalline LiMnPO{sub 4} material was synthesized by template free sucrose assisted hydrothermal synthesis. The material possess orthorhombic crystal structure with Pnma, space group having four formula units. The structural characterization was accomplished through X-ray diffraction, thermo gravimetry/differential thermal analysis. Morphology was identified by the SEM, VSM was used to verify the magnetic behavior of the material and electrical characterization was done through impedance spectroscopy and the results were reported.

High-quality fuel from food waste - investigation of a stepwise process from the perspective of technology development.

PubMed

Yin, Ke; Li, Ling; Giannis, Apostolos; Weerachanchai, Piyarat; Ng, Bernard J H; Wang, Jing-Yuan

2017-07-01

A stepwise process (SP) was developed for sustainable energy production from food waste (FW). The process comprised of hydrothermal treatment followed by oil upgrading. Synthetic food waste was primarily used as feedstock in the hydrothermal reactor under subcritical water conditions. The produced hydrochars were analyzed for calorific value (17.0-33.7 MJ/kg) and elemental composition indicating high-quality fuel comparable to coal. Hydrothermal carbonization (e.g. 180°C) would be efficient for oil recovery (>90%) from FW, as compared to hydrothermal liquefaction (320°C) whereby lipid degradation may take place. The recovered oil was upgraded to biodiesel in a catalytic refinery process. Selected biodiesels, that is, B3 and B4 were characterized for density (872.7 and 895.5 kg/m 3 ), kinematic viscosity (3.115 and 8.243 cSt), flash and pour point (30°C and >126°C), micro carbon (0.03% and 0.04%), sulfur (both <0.0016%), and calorific value (38,917 and 39,584 J/g), suggesting similar quality to commercial biodiesel. Fatty acid methyl ethers content was further analyzed to assess the influence of hydrothermal treatment in biodiesel quality, indicating the limited impacts. Overall, the SP provides a promising alternative for sustainable energy recovery through high-quality biofuel and hydrochar production.

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. Copyright © 2015 Elsevier Ltd. All rights reserved.

Magnesium isotopic behavior during the formation of chlorite-rich hydrothermal sediment in the middle Okinawa Trough

NASA Astrophysics Data System (ADS)

Shao, H.; Yang, S.; Teng, F. Z.; Cai, D.; Humphris, S. E.

2016-12-01

Chlorite is a common alteration product during water-rock reactions in seafloor hydrothermal systems. This chlorite is commonly characterized by high concentrations of magnesium. However, the source of the Mg and its behavior during hydrothermal alteration have yet to be clarified. Mg isotopes have been used in recent years to investigate a variety of geological processes, including low temperature weathering and metamorphism processes, and Mg cycling in sediments. In this study, we investigate the source of Mg and its behavior in chlorite-rich sediments collected during IODP Expedition 331 from the active hydrothermal Iheya North Knoll field in the middle Okinawa Trough — an intra-continental rift in continental crust. This area is characterized by hemipelagic muds with interbedded thick layers of felsic pumiceous volcanic material. Based on mineralogical, geochemical, and isotopic data, we have previously suggested that the chlorite-rich sediments resulted from hydrothermal alteration of the pumiceous layers at temperatures of 220-300°C. Prior to Mg isotope analysis, all selected samples were pretreated with 1N HCl in order to remove carbonates and other unstable minerals, and measurements were made on both the residues (mainly chlorite) and leachates, as well as on bulk samples. The residues are expected to show higher δ26Mg than the leachates reflecting the Mg isotopic signature of the pumiceous material precursor and provide insight into the behavior of Mg isotopes during the high-temperature hydrothermal processes.

High-resolution Topography of PACMANUS and DESMOS Hydrothermal Fields in the Manus Basin through ROV "FAXIAN"

NASA Astrophysics Data System (ADS)

Luan, Z.; Ma, X.; Yan, J.; Zhang, X.; Zheng, C.; Sun, D.

2016-12-01

High-resolution topography can help us deeply understand the seabed and related geological processes (e.g. hydrothermal/cold spring systems) in the deep sea areas. However, such studies are rare in China due to the limit of deep-sea detection technology. Here, we report the advances of the application of ROV in China and the newly measured high-resolution topographical data in PACMANUS and DESMOS hydrothermal fields. In June 2015, the ROV "FAXIAN" with a multibeam system (Kongsberg EM2040) was deployed to measure the topography of PACMANUS and DESMOS hydrothermal fields in the Manus basin. A composite positioning system on the ROV provided long baseline (LBL) navigation and positioning during measurements, giving a high positioning accuracy (better than 0.5m). The raw bathymetric data obtained were processed using CARIS HIPS (version 8.1). Based on the high-resolution data, we can describe the topographical details of the PACMANUS and DESMOS hydrothermal fields. High-resolution terrain clearly shows the detailed characters of the topography in the PACMANUS hydrothermal field, and some cones are corresponding to the pre discovered hydrothermal points and volcanic area. Most hydrothermal points in the PACMANUS hydrothermal field mainly developed on the steep slopes with a gradient exceeding 30 °. In contrast, the DESMOS field is a caldera that is approximately 250 m deep in the center with an E-W diameter of approximately1 km and a N-S diameter of approximately 2 km. The seafloor is much steeper on the inner side of the circular fracture. Two highlands occur in the northern and the southern flanks of the caldera. Video record indicated that pillow lava, sulfide talus, breccia, anhydrite, outcrops, and sediment all appeared in the DESMOS field. This is the first time for the ROV "FAXIAN" to be used in near-bottom topography measurements in the hydrothermal fields, opening a window of deep-sea researches in China.

The Production of Methane, Hydrogen, and Organic Compounds in Ultramafic-Hosted Hydrothermal Vents of the Mid-Atlantic Ridge

PubMed Central

Charlou, J.L.; Holm, N.G.; Mousis, O.

2015-01-01

Abstract Both hydrogen and methane are consistently discharged in large quantities in hydrothermal fluids issued from ultramafic-hosted hydrothermal fields discovered along the Mid-Atlantic Ridge. Considering the vast number of these fields discovered or inferred, hydrothermal fluxes represent a significant input of H2 and CH4 to the ocean. Although there are lines of evidence of their abiogenic formation from stable C and H isotope results, laboratory experiments, and thermodynamic data, neither their origin nor the reaction pathways generating these gases have been fully constrained yet. Organic compounds detected in the fluids may also be derived from abiotic reactions. Although thermodynamics are favorable and extensive experimental work has been done on Fischer-Tropsch-type reactions, for instance, nothing is clear yet about their origin and formation mechanism from actual data. Since chemolithotrophic microbial communities commonly colonize hydrothermal vents, biogenic and thermogenic processes are likely to contribute to the production of H2, CH4, and other organic compounds. There seems to be a consensus toward a mixed origin (both sources and processes) that is consistent with the ambiguous nature of the isotopic data. But the question that remains is, to what proportions? More systematic experiments as well as integrated geochemical approaches are needed to disentangle hydrothermal geochemistry. This understanding is of prime importance considering the implications of hydrothermal H2, CH4, and organic compounds for the ocean global budget, global cycles, and the origin of life. Key Words: Hydrogen—Methane—Organics—MAR—Abiotic synthesis—Serpentinization—Ultramafic-hosted hydrothermal vents. Astrobiology 15, 381–399. PMID:25984920

Hydrothermal impacts on trace element and isotope ocean biogeochemistry.

PubMed

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

2016-11-28

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'. © 2015 The Authors.

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’. PMID:29035265

Hydrothermal solidification of municipal solid waste incineration bottom ash with slag addition.

PubMed

Jing, Zhenzi; Ran, Xianqiang; Jin, Fangming; Ishida, Emile H

2010-01-01

Hydrothermal solidification of municipal solid waste incineration (MSWI) bottom ash has been carried out under saturated steam pressure (1.56 MPa) at 200 degrees C for up to 24 h by mixing quartz, slaked lime and water-cooled blast furnace slag (WBFS). The strength enhancement for the WBFS addition was best. The strength development was shown to be due mainly to tobermorite formation, and the tobermorite formation densified matrix, thus promoting the strength development. WBFS seemed to have a higher reactivity than the quartz during the initial hydrothermal process, which provided more silica available to harden the solidified specimens. However, a longer curing time (24 h) was favorable to the quartz dissolution for tobermorite formation, which in turn, enhanced the strength for quartz addition. Curing time affected the crystal morphology evolution, and the stubby plate of tobermorite seemed to result in a high strength enhancement in this study. Laboratory leaching tests were conducted to determine the amount of heavy metals dissolved from the final solidified specimens, and the leaching results showed that after hydrothermal processing the heavy metals dissolved from the solidified specimens were reduced effectively. As such, the hydrothermal processing may have a high potential for recycling/reusing MSWI ash on a large scale. 2010 Elsevier Ltd. All rights reserved.

The role of magmas in the formation of hydrothermal ore deposits

USGS Publications Warehouse

Hedenquist, Jeffrey W.; Lowenstern, Jacob B.

1994-01-01

Magmatic fluids, both vapour and hypersaline liquid, are a primary source of many components in hydrothermal ore deposits formed in volcanic arcs. These components, including metals and their ligands, become concentrated in magmas in various ways from various sources, including subducted oceanic crust. Leaching of rocks also contributes components to the hydrothermal fluid—a process enhanced where acid magmatic vapours are absorbed by deeply circulating meteoric waters. Advances in understanding the hydrothermal systems that formed these ore deposits have come from the study of their active equivalents, represented at the surface by hot springs and volcanic fumaroles.

Cooling of Kilauea Iki lava lake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hills, R.G.

1982-02-01

In 1959 Kilauea Iki erupted leaving a 110 to 120 m lake of molten lava in its crater. The resulting lava lake has provided a unique opportunity to study the cooling dynamics of a molten body and its associated hydrothermal system. Field measurements taken at Kilauea Iki indicate that the hydrothermal system above the cooling magma body goes through several stages, some of which are well modeled analytically. Field measurements also indicate that during most of the solidification period of the lake, cooling from above is controlled by 2-phase convection while conduction dominates the cooling of the lake from below.more » A summary of the field work related to the study of the cooling dynamics of Kilauea Iki is presented. Quantitative and qualitative cooling models for the lake are discussed.« less

Lack of Microbial Diversity in an Extreme Mars Analog Setting: Poás Volcano, Costa Rica.

PubMed

Hynek, Brian M; Rogers, Karyn L; Antunovich, Monique; Avard, Geoffroy; Alvarado, Guillermo E

2018-04-24

The Poás volcano in Costa Rica has been studied as a Mars geochemical analog environment, since both the style of hydrothermal alteration present and the alteration mineralogy are consistent with Mars' relict hydrothermal systems. The site hosts an active volcano, with high-temperature fumaroles (up to 980°C) and an ultra-acidic lake. This lake, Laguna Caliente, is one of the most dynamic environments on Earth, with frequent phreatic eruptions, temperatures ranging from near-ambient to almost boiling, a pH range of -1 to 1.5, and a wide range of chemistries and redox potential. Martian acid-sulfate hydrothermal systems were likely similarly dynamic and equally challenging to life. The microbiology existing within Laguna Caliente was characterized for the first time, with sampling taking place in November, 2013. The diversity of the microbial community was surveyed via extraction of environmental DNA from fluid and sediment samples followed by Illumina sequencing of the 16S rRNA gene. The microbial diversity was limited to a single species of the bacterial genus Acidiphilium. This organism likely gets its energy from oxidation of reduced sulfur in the lake, including elemental sulfur. Given Mars' propensity for sulfur and acid-sulfate environments, this type of organism is of significant interest to the search for past or present life on the Red Planet. Key Words: Mars astrobiology-Acid-sulfate hydrothermal systems-Extremophiles-Acidic-High temperature-Acidiphilium bacteria. Astrobiology 18, xxx-xxx.

Effective utilizations of palm oil mill fly ash for synthetic amorphous silica and carbon zeolite composite synthesis

NASA Astrophysics Data System (ADS)

Utama, P. S.; Saputra, E.; Khairat

2018-04-01

Palm Oil Mill Fly Ash (POMFA) the solid waste of palm oil industry was used as a raw material for synthetic amorphous silica and carbon zeolite composite synthesis in order to minimize the wastes of palm oil industry. The alkaline extraction combine with the sol-gel precipitation and mechanical fragmentation was applied to produce synthetic amorphous silica. The byproduct, extracted POMFA was rich in carbon and silica content in a significant amount. The microwave heated hydrothermal process used to synthesize carbon zeolite composite from the byproduct. The obtained silica had chemical composition, specific surface area and the micrograph similar to commercial precipitated silica for rubber filler. The microwave heated hydrothermal process has a great potential for synthesizing carbon zeolite composite. The process only needs one-step and shorter time compare to conventional hydrothermal process.

Chemical environments of submarine hydrothermal systems. [supporting abiogenetic theory

NASA Technical Reports Server (NTRS)

Shock, Everett L.

1992-01-01

The paper synthesizes diverse information about the inorganic geochemistry of submarine hydrothermal systems, provides a description of the fundamental physical and chemical properties of these systems, and examines the implications of high-temperature, fluid-driven processes for organic synthesis. Emphasis is on a few general features, i.e., pressure, temperature, oxidation states, fluid composition, and mineral alteration, because these features will control whether organic synthesis can occur in hydrothermal systems.

In situ study of the factors controlling Fe, Cu and Zn scavenging during the early mixing between hydrothermal fluids and seawater

NASA Astrophysics Data System (ADS)

Cathalot, C.; Laes-Huon, A.; Pelleter, E.; Maillard, L.; Chéron, S.; Boissier, A.; Waeles, M.; Cotte, L.; Pernet-Coudrier, B.; Gayet, N.; Sarrazin, J.; Sarradin, P. M.

2016-12-01

Despite the importance of trace metals for marine ecosystems and in the global carbon cycle, dissolved metal sources in the deep ocean and their export mechanism are, today, still unconstrained. The historical view that dissolved metals are largely removed from hydrothermal plumes through precipitation of a range of iron-bearing minerals is now being challenged. Several potential mechanisms for the delivery of hydrothermally sourced metals to the open ocean have been suggested and require a thorough documentation of the early mixing processes between the hydrothermal fluids and the ambient seawater. The geochemistry of a plume, and specially the rising plume, is dictated by the nature and composition of the host rock, fluid temperature, phase separation at depth and subsurface mixing processes, and thus can vary in temperature, pH, metal and dissolved gases content between spatially close hydrothermal vents. Here, we present in situ chemical conditions during the early mixing gradient between hydrothermal fluids and seawater at the Lucky Strike site (Mid-Atlantic Ridge), using a multi proxy approach targeting both the dissolved and particulate phase and combining in situ measurements and analysis back in the lab. Indeed, in situ O2, H2S and temperature measurements were performed at a 1Hz frequency, coupled to lower frequency analysis of in situ Fe2+. In addition, particulate material filtered in situ was analyzed using Inductive Coupled Plasma - Mass Spectrometry, X-Ray Diffraction, X-Ray Fluorescence and Scanning Electron Microscopy and provided useful insights regarding the reactivity of metals during the mixing processes. Our results show different behavior within the Lucky Strike vent field. Fe and S co-precipitation through chalcopyrite formation at the newly discovered Capelinhos site seem to be the main process. At the White Caste site, on the other hand, wurzite and sphalerite precipitation seems to dominate the dilution processes, H2S being rapidly titrated with the available Zinc early in the mixing. Our results indicate a clear control by subsurface mixing processes, at a very local scale: within a single vent field, temperature outflow of the hydrothermal fluid clearly drives Cu, Fe and Zn scavenging in the particulate phase, and controlling hence the iron stability and export.

Molybdenum isotope behaviour in groundwaters and terrestrial hydrothermal systems, Iceland

NASA Astrophysics Data System (ADS)

Neely, Rebecca A.; Gislason, Sigurdur R.; Ólafsson, Magnus; McCoy-West, Alex J.; Pearce, Christopher R.; Burton, Kevin W.

2018-03-01

Molybdenum (Mo) isotopes have proved useful in the reconstruction of paleoredox conditions. Their application generally relies upon a simplified model of ocean inputs in which rivers dominate Mo fluxes to the oceans and hydrothermal fluids are considered to be a minor contribution. To date, however, little attention has been paid to the extent of Mo isotope variation of hydrothermal waters, or to the potential effect of direct groundwater discharge to the oceans. Here we present Mo isotope data for two Icelandic groundwater systems (Mývatn and Þeistareykir) that are both influenced by hydrothermal processes. Relative to NIST 3134 = +0.25‰, the cold (<10 °C) groundwaters (δ98/95MoGROUNDWATER = -0.15‰ to +0.47‰; n = 13) show little, if any, fractionation from the host basalt (δ 98 / 95MoBASALT = +0.16‰ to -0.12‰) and are, on average, lighter than both global and Icelandic rivers. In contrast, waters that are hydrothermally influenced (>10 °C) possess isotopically heavy δ98/95MoHYDROTHERMAL values of +0.25‰ to +2.06‰ (n = 18) with the possibility that the high temperature endmembers are even heavier. Although the mechanisms driving this fractionation remain unresolved, the incongruent dissolution of the host basalt and both the dissolution and precipitation of sulfides are considered. Regardless of the processes driving these variations, the δ98Mo data presented in this study indicate that groundwater and hydrothermal waters have the potential to modify ocean budget calculations.

Origin of Abiotic Methane in Submarine Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Seewald, J. S.; German, C. R.; Grozeva, N. G.; Klein, F.; McDermott, J. M.; Ono, S.; Reeves, E. P.; Wang, D. T.

2018-05-01

Results of recent investigations into the chemical and isotopic composition of actively venting submarine hydrothermal fluids and volatile species trapped in fluid inclusions will be discussed in the context of processes responsible for abiotic CH4 formation.

Synthesis and microwave modification of CuO nanoparticles: crystallinity and morphological variations, catalysis, and gas sensing.

PubMed

Yang, Chao; Xiao, Feng; Wang, Jide; Su, Xintai

2014-12-01

CuO nanoparticles with different morphologies were synthesized by chemical precipitation and subsequently modified by microwave hydrothermal processing. The nanoparticles were precipitated by the introduction of a strong base to an aqueous solution of copper cations in the presence/absence of the polyethylene glycol and urea additives. The modification of the nanoparticles was subsequently carried out by a microwave hydrothermal treatment of suspensions of the precipitates, precipitated with and without the additives. X-ray powder diffraction analysis indicated that the crystallinity and crystallite size of the CuO nanoparticles increased after the microwave hydrothermal modification. Microscopy observations revealed the morphology changes induced by microwave hydrothermal processing. The thermal decomposition of ammonium perchlorate and the detection of volatile gases were performed to evaluate the catalytic and gas sensing properties of the synthesized CuO nanoparticles. Copyright © 2014 Elsevier Inc. All rights reserved.

Process characteristics for microwave assisted hydrothermal carbonization of cellulose.

PubMed

Zhang, Junting; An, Ying; Borrion, Aiduan; He, Wenzhi; Wang, Nan; Chen, Yirong; Li, Guangming

2018-07-01

The process characteristics of microwave assisted hydrothermal carbonization of cellulose was investigated and a first order kinetics model based on carbon concentration was developed. Chemical properties analysis showed that comparing to conventional hydrothermal carbonization, hydrochar with comparable energy properties can be obtained with 5-10 times decrease in reaction time with assistance of microwave heating. Results from kinetics study was in great agreement with experimental analysis, that they both illustrated the predominant mechanism of the reaction depend on variations in the reaction rates of two co-existent pathways. Particularly, the pyrolysis-like intramolecular dehydration reaction was proved to be the predominant mechanism for hydrochar generation under high temperatures. Finally, the enhancement effects of microwave heating were reflected under both soluble and solid pathways in this research, suggesting microwave-assisted hydrothermal carbonization as a more attracting method for carbon-enriched hydrochar recovery. Copyright © 2018 Elsevier Ltd. All rights reserved.

Spatial Distribution of Viruses Associated with Planktonic and Attached Microbial Communities in Hydrothermal Environments

PubMed Central

Nunoura, Takuro; Kazama, Hiromi; Noguchi, Takuroh; Inoue, Kazuhiro; Akashi, Hironori; Yamanaka, Toshiro; Toki, Tomohiro; Yamamoto, Masahiro; Furushima, Yasuo; Ueno, Yuichiro; Yamamoto, Hiroyuki; Takai, Ken

2012-01-01

Viruses play important roles in marine surface ecosystems, but little is known about viral ecology and virus-mediated processes in deep-sea hydrothermal microbial communities. In this study, we examined virus-like particle (VLP) abundances in planktonic and attached microbial communities, which occur in physical and chemical gradients in both deep and shallow submarine hydrothermal environments (mixing waters between hydrothermal fluids and ambient seawater and dense microbial communities attached to chimney surface areas or macrofaunal bodies and colonies). We found that viruses were widely distributed in a variety of hydrothermal microbial habitats, with the exception of the interior parts of hydrothermal chimney structures. The VLP abundance and VLP-to-prokaryote ratio (VPR) in the planktonic habitats increased as the ratio of hydrothermal fluid to mixing water increased. On the other hand, the VLP abundance in attached microbial communities was significantly and positively correlated with the whole prokaryotic abundance; however, the VPRs were always much lower than those for the surrounding hydrothermal waters. This is the first report to show VLP abundance in the attached microbial communities of submarine hydrothermal environments, which presented VPR values significantly lower than those in planktonic microbial communities reported before. These results suggested that viral lifestyles (e.g., lysogenic prevalence) and virus interactions with prokaryotes are significantly different among the planktonic and attached microbial communities that are developing in the submarine hydrothermal environments. PMID:22210205

The Irony of Iron – Biogenic Iron Oxides as an Iron Source to the Ocean

PubMed Central

Emerson, David

2016-01-01

Primary productivity in at least a third of the sunlit open ocean is thought to be iron-limited. Primary sources of dissolved iron (dFe) to the ocean are hydrothermal venting, flux from the sediments along continental margins, and airborne dust. This article provides a general review of sources of hydrothermal and sedimentary iron to the ocean, and speculates upon the role that iron-cycling microbes play in controlling iron dynamics from these sources. Special attention is paid to iron-oxidizing bacteria (FeOB) that live by oxidizing iron and producing biogenic iron oxides as waste products. The presence and ubiquity of FeOB both at hydrothermal systems and in sediments is only beginning to be appreciated. The biogenic oxides they produce have unique properties that could contribute significantly to the dynamics of dFe in the ocean. Changes in the physical and chemical characteristics of the ocean due to climate change and ocean acidification will undoubtedly impact the microbial iron cycle. A better understanding of the contemporary role of microbes in the iron cycle will help in predicting how these changes could ultimately influence marine primary productivity. PMID:26779157

Phenols in hydrothermal petroleums and sediment bitumen from Guaymas Basin, Gulf of California

NASA Technical Reports Server (NTRS)

Simoneit, B. R.; Leif, R. N.; Ishiwatari, R.

1996-01-01

The aliphatic, aromatic and polar (NSO) fractions of seabed petroleums and sediment bitumen extracts from the Guaymas Basin hydrothermal system have been analyzed by gas chromatography and gas chromatography-mass spectrometry (free and silylated). The oils were collected from the interiors and exteriors of high temperature hydrothermal vents and represent hydrothermal pyrolyzates that have migrated to the seafloor by hydrothermal fluid circulation. The downcore sediments are representative of both thermally unaltered and thermally altered sediments. The survey has revealed the presence of oxygenated compounds in samples with a high degree of thermal maturity. Phenols are one class of oxygenated compounds found in these samples. A group of methyl-, dimethyl- and trimethyl-isoprenoidyl phenols (C27-C29) is present in all of the seabed NSO fractions, with the methyl- and dimethyl-isoprenoidyl phenols occurring as major components, and a trimethyl-isoprenoidyl phenol as a minor component. A homologous series of n-alkylphenols (C13-C33) has also been found in the seabed petroleums. These phenols are most likely derived from the hydrothermal alteration of sedimentary organic matter. The n-alkylphenols are probably synthesized under hydrothermal conditions, but the isoprenoidyl phenols are probably hydrothermal alteration products of natural product precursors. The suites of phenols do not appear to be useful tracers of high temperature hydrothermal processes.

Anatomy of a fumarolic system inferred from a multiphysics approach.

PubMed

Gresse, Marceau; Vandemeulebrouck, Jean; Byrdina, Svetlana; Chiodini, Giovanni; Roux, Philippe; Rinaldi, Antonio Pio; Wathelet, Marc; Ricci, Tullio; Letort, Jean; Petrillo, Zaccaria; Tuccimei, Paola; Lucchetti, Carlo; Sciarra, Alessandra

2018-05-15

Fumaroles are a common manifestation of volcanic activity that are associated with large emissions of gases into the atmosphere. These gases originate from the magma, and they can provide indirect and unique insights into magmatic processes. Therefore, they are extensively used to monitor and forecast eruptive activity. During their ascent, the magmatic gases interact with the rock and hydrothermal fluids, which modify their geochemical compositions. These interactions can complicate our understanding of the real volcanic dynamics and remain poorly considered. Here, we present the first complete imagery of a fumarolic plumbing system using three-dimensional electrical resistivity tomography and new acoustic noise localization. We delineate a gas reservoir that feeds the fumaroles through distinct channels. Based on this geometry, a thermodynamic model reveals that near-surface mixing between gas and condensed steam explains the distinct geochemical compositions of fumaroles that originate from the same source. Such modeling of fluid interactions will allow for the simulation of dynamic processes of magmatic degassing, which is crucial to the monitoring of volcanic unrest.

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 and vein-fi lling; and (5) areal dimensions of many large hydrothermal explosion craters in Yellowstone are similar to those of its active geyser basins and thermal areas. For Yellowstone, our knowledge of hydrothermal craters and ejecta is generally limited to after the Yellowstone Plateau emerged from beneath a late Pleistocene icecap that was roughly a kilometer thick. Large hydrothermal explosions may have occurred earlier as indicated by multiple episodes of cementation and brecciation commonly observed in hydrothermal ejecta clasts. Critical components for large, explosive hydrothermal systems include a watersaturated system at or near boiling temperatures and an interconnected system of well-developed joints and fractures along which hydrothermal fluids flow. Active deformation of the Yellowstone caldera, active faulting and moderate local seismicity, high heat flow, rapid changes in climate, and regional stresses are factors that have strong infl uences on the type of hydrothermal system developed. Ascending hydrothermal fluids flow along fractures that have developed in response to active caldera deformation and along edges of low-permeability rhyolitic lava flows. Alteration of the area affected, self-sealing leading to development of a caprock for the hydrothermal system, and dissolution of silica-rich rocks are additional factors that may constrain the distribution and development of hydrothermal fields. A partial lowpermeability layer that acts as a cap to the hydrothermal system may produce some over-pressurization, thought to be small in most systems. Any abrupt drop in pressure initiates steam fl ashing and is rapidly transmitted through interconnected fractures that result in a series of multiple large-scale explosions contributing to the excavation of a larger explosion crater. Similarities between the size and dimensions of large hydrothermal explosion craters and thermal fields in Yellowstone may indicate that catastrophic events which result in l

Subevents of long-period seismicity: implications for hydrothermal dynamics during the 2004-2008 eruption of Mount St. Helens

USGS Publications Warehouse

Matoza, Robin S.; Chouet, Bernard A.

2010-01-01

One of the most striking aspects of seismicity during the 2004–2008 eruption of Mount St. Helens (MSH) was the precise regularity in occurrence of repetitive long-period (LP) or “drumbeat” events over sustained time periods. However, this precise regularity was not always observed, and at times the temporal occurrence of LP events became more random. In addition, accompanying the dominant LP class of events during the 2004–2008 MSH eruption, there was a near-continuous, randomly occurring series of smaller seismic events. These subevents are not always simply small-amplitude versions of the dominant LP class of events but appear instead to result from a separate random process only loosely coupled to the main LP source mechanism. We present an analysis of the interevent time and amplitude distributions of the subevents, using waveform cross correlation to separate LP events from the subevents. We also discuss seismic tremor that accompanied the 8 March 2005 phreatic explosion event at MSH. This tremor consists of a rapid succession of LPs and subevents triggered during the explosion, in addition to broadband noise from the sustained degassing. Immediately afterward, seismicity returned to the pre-explosion occurrence pattern. This triggering in relation to the rapid ejection of steam from the system, and subsequent return to pre-explosion seismicity, suggests that both seismic event types originated in a region of the subsurface hydrothermal system that was (1) in contact with the reservoir feeding the 8 March 2005 phreatic explosion but (2) not destroyed or drained by the explosion event. Finally, we discuss possible thermodynamic conditions in a pressurized hydrothermal crack that could give rise to seismicity. Pressure drop estimates for typical LP events are not generally large enough to perturb pure water in a shallow hydrothermal crack into an unstable state. However, dissolved volatiles such as CO2 may lead to a more unstable system, increasing the seismogenic potential of a hydrothermal crack subject to rapid heat flux. The interaction of hydrothermal and magmatic systems beneath MSH in 2004–2008 thus appears able to explain a wide range of observed phenomena, including subevents, LP events, larger (Md > 2) events, and phreatic explosions.

Restoration of water environment contaminated by radioactive cesium released from Fukushima Daiichi NPP

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takeshita, K.; Takahashi, H.; Jinbo, Y.

2013-07-01

In the Fukushima Daiichi NPP Accident, large amounts of volatile radioactive nuclides, such as {sup 131}I, {sup 134}Cs and {sup 137}Cs, were released to the atmosphere and huge areas surrounding the nuclear site were contaminated by the radioactive fallout. In this study, a combined process with a hydrothermal process and a coagulation settling process was proposed for the separation of radioactive Cs from contaminated soil and sewage sludge. The coagulation settling operation uses Prussian Blue (Ferric ferrocyanide) and an inorganic coagulant. The recovery of Cs from sewage sludge sampled at Fukushima city (100.000 Bq/kg) and soil at a nearby villagemore » (55.000 Bq/kg), was tested. About 96% of Cs in the sewage sludge was removed successfully by combining simple hydrothermal decomposition and coagulation settling. However, Cs in the soil was not removed sufficiently by the combined process (Cs removal is only 56%). The hydrothermal decomposition with blasting was carried out. The Cs removal from the soil was increased to 85%. When these operations were repeated twice, the Cs recovery was over 90%. The combined process with hydrothermal blasting and coagulation settling is applicable to the removal of Cs from highly contaminated soil.« less

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.

Biotic interactions at hydrothermal vents: Recruitment inhibition by the mussel Bathymodiolus thermophilus

NASA Astrophysics Data System (ADS)

Lenihan, H. S.; Mills, S. W.; Mullineaux, L. S.; Peterson, C. H.; Fisher, C. R.; Micheli, F.

2008-12-01

The structure and dynamics of marine communities are regulated in part by variation in recruitment. As in other ecosystems, recruitment at deep-sea hydrothermal vents is controlled by the interplay of propagule supply and behavior, gradients in physical-chemical conditions, and biotic interactions during pre- and post-settlement periods. Recent research along the East Pacific Rise indicates that inhibition of recently settled larvae by mobile predators (mainly limpets) influences patterns of recruitment and subsequent community succession. We conducted a manipulative experiment at the same sites (˜2510 m water depth) to test whether high-density assemblages of the mussel Bathymodiolus thermophilus also inhibit recruitment. In a preliminary study, recruitment of vent invertebrates within the faunal zone dominated by B. thermophilus was strikingly different at two sites, East Wall and Worm Hole. East Wall had high densities of mussels but very low total recruitment. In contrast, Worm Hole had few mussels but high recruitment. Using the submersible Alvin, we transplanted a large number of mussels from East Wall to Worm Hole and quantified recruitment on basalt blocks placed in three treatments: (1) naturally high densities of mussels at East Wall; (2) naturally low densities of mussels at Worm Hole; and (3) high densities of transplanted mussels at Worm Hole. After 11 months, a total of 24 taxa had recruited to the basalt blocks. Recruitment was 44-60% lower in the transplanted high-density mussel patch at Worm Hole and the natural high-density patch at East Wall than within the natural low-density patch at Worm Hole. Biotic processes that may have caused the pattern of recruitment observed included predation of larvae via water filtration by mussels, larval avoidance of superior competitors, interference competition, and enhanced predation by species within the mussel-bed community. Our results indicate that biotic interactions affecting recruitment must be understood to explain patterns of invertebrate community organization and dynamics at hydrothermal vents.

Spatial and temporal variations of thaw layer thickness and its controlling factors identified using time-lapse electrical resistivity tomography and hydro-thermal modeling

NASA Astrophysics Data System (ADS)

Tran, Anh Phuong; Dafflon, Baptiste; Bisht, Gautam; Hubbard, Susan S.

2018-06-01

Quantitative understanding of controls on thaw layer thickness (TLT) dynamics in the Arctic peninsula is essential for predictive understanding of permafrost degradation feedbacks to global warming and hydrobiochemical processes. This study jointly interprets electrical resistivity tomography (ERT) measurements and hydro-thermal numerical simulation results to assess spatiotemporal variations of TLT and to determine its controlling factors in Barrow, Alaska. Time-lapse ERT measurements along a 35-m transect were autonomously collected from 2013 to 2015 and inverted to obtain soil electrical resistivity. Based on several probe-based TLT measurements and co-located soil electrical resistivity, we estimated the electrical resistivity thresholds associated with the boundary between the thaw layer and permafrost using a grid search optimization algorithm. Then, we used the obtained thresholds to derive the TLT from all soil electrical resistivity images. The spatiotemporal analysis of the ERT-derived TLT shows that the TLT at high-centered polygons (HCPs) is smaller than that at low-centered polygons (LCPs), and that both thawing and freezing occur earlier at the HCPs compared to the LCPs. In order to provide a physical explanation for dynamics in the thaw layer, we performed 1-D hydro-thermal simulations using the community land model (CLM). Simulation results showed that air temperature and precipitation jointly govern the temporal variations of TLT, while the topsoil organic content (SOC) and polygon morphology are responsible for its spatial variations. When the topsoil SOC and its thickness increase, TLT decreases. Meanwhile, at LCPs, a thicker snow layer and saturated soil contribute to a thicker TLT and extend the time needed for TLT to freeze and thaw. This research highlights the importance of combination of measurements and numerical modeling to improve our understanding spatiotemporal variations and key controls of TLT in cold regions.

Preparation and Stoichiometry Effects on Microstructure and Properties of High Purity BaTiO3.

DTIC Science & Technology

1986-03-27

oxalate , citrate) salt solutions, from mixed alkoxide precursors or from hydrothermal solutions. Typical starting materials and reaction sequences...decomposition and calcination reactions to form the BaTiO compound. Both the oxalate and 3 hydrothermal processes show commnercial promise and are briefly...thermal decomposition of oxalates and by hydrothermal synthesis. As-received lots of mixed oxide and oxalate -derived powders had Ba:TI ratios of 0.997 and

Juvenile magma recognition and eruptive dynamics inferred from the analysis of ash time series: The 2015 reawakening of Cotopaxi volcano

USGS Publications Warehouse

Gaunt, H. Elizabeth; Bernard, Benjamin; Hidalgo, Silvana; Proano, Antonio; Wright, Heather M.; Mothes, Patricia; Criollo, Evelyn; Kueppers, Ulrich

2016-01-01

Forecasting future activity and performing hazard assessments during the reactivation of volcanoes remain great challenges for the volcanological community. On August 14, 2015 Cotopaxi volcano erupted for the first time in 73 years after approximately four months of precursory activity, which included an increase in seismicity, gas emissions, and minor ground deformation. Here we discuss the use of near real-time petrological monitoring of ash samples as a complementary aid to geophysical monitoring, in order to infer eruption dynamics and evaluate possible future eruptive activity at Cotopaxi. Twenty ash samples were collected between August 14 and November 23, 2015 from a monitoring site on the west flank of the volcano. These samples contain a range of grain types that we classified as: hydrothermal/altered, lithic, juvenile, and free crystals. The relative proportions of theses grains evolved as the eruption progressed, with increasing amounts of juvenile material and a decrease in hydrothermally altered material. In samples from the initial explosion, juvenile grains are glassy, microlite-poor and contain hydrothermal minerals (opal and alunite). The rising magma came in contact with the hydrothermal system under confinement, causing hydro-magmatic explosions that cleared the upper part of the plumbing system. Subsequently, the magmatic column produced a thermal aureole in the conduit and dried out the hydrothermal system, allowing for dry eruptions. Magma ascent rates were low enough to allow for efficient outgassing and microlite growth. Constant supply of magma from below caused quasi-continuous disruption of the uppermost magma volume through a combination of shear-deformation and gas expansion. The combination of increasing crystallinity of juvenile grains, and high measured SO2 flux indicate decreasing integrated magma ascent rates and clearing of the hydrothermal system along transport pathways in a system open to gas loss. The near real-time monitoring of ash samples combined with traditional geophysical monitoring techniques during the reawakening of Cotopaxi allowed us to gain a much clearer understanding of events than when using traditional geophysical monitoring alone.

Speciation and Structural Properties of Hydrothermal Solutions of Sodium and Potassium Sulfate Studied by Molecular Dynamics Simulations.

PubMed

Reimer, Joachim; Vogel, Frédéric; Steele-MacInnis, Matthew

2016-05-18

Aqueous solutions of salts at elevated pressures and temperatures play a key role in geochemical processes and in applications of supercritical water in waste and biomass treatment, for which salt management is crucial for performance. A major question in predicting salt behavior in such processes is how different salts affect the phase equilibria. Herein, molecular dynamics (MD) simulations are used to investigate molecular-scale structures of solutions of sodium and/or potassium sulfate, which show contrasting macroscopic behavior. Solutions of Na-SO4 exhibit a tendency towards forming large ionic clusters with increasing temperature, whereas solutions of K-SO4 show significantly less clustering under equivalent conditions. In mixed systems (Nax K2-x SO4 ), cluster formation is dramatically reduced with decreasing Na/(K+Na) ratio; this indicates a structure-breaking role of K. MD results allow these phenomena to be related to the characteristics of electrostatic interactions between K(+) and SO4 (2-) , compared with the analogous Na(+) -SO4 (2-) interactions. The results suggest a mechanism underlying the experimentally observed increasing solubility in ternary mixtures of solutions of Na-K-SO4 . Specifically, the propensity of sodium to associate with sulfate, versus that of potassium to break up the sodium-sulfate clusters, may affect the contrasting behavior of these salts. Thus, mutual salting-in in ternary hydrothermal solutions of Na-K-SO4 reflects the opposing, but complementary, natures of Na-SO4 versus K-SO4 interactions. The results also provide clues towards the reported liquid immiscibility in this ternary system. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles

NASA Astrophysics Data System (ADS)

Kshetri, Yuwaraj K.; Regmi, Chhabilal; Kim, Hak-Soo; Wohn Lee, Soo; Kim, Tae-Ho

2018-05-01

Yb3+ and Er3+ doped YVO4 (Yb3+/Er3+:YVO4) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb3+/Er3+:YVO4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2H11/2, 4S3/2 to 4I15/2 and 4F9/2 to 4I15/2 transitions of Er3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb3+. The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

Microwave hydrothermal synthesis and upconversion properties of Yb3+/Er3+ doped YVO4 nanoparticles.

PubMed

Kshetri, Yuwaraj K; Regmi, Chhabilal; Kim, Hak-Soo; Lee, Soo Wohn; Kim, Tae-Ho

2018-05-18

Yb 3+ and Er 3+ doped YVO 4 (Yb 3+ /Er 3+ :YVO 4 ) nanoparticles with highly efficient near-infrared to visible upconversion properties have been synthesized by microwave hydrothermal process. Uniform-sized Yb 3+ /Er 3+ :YVO 4 nanoparticles were synthesized within 1 h at 140 °C which is relatively faster than the conventional hydrothermal process. Under 980 nm laser excitation, strong green and less strong red emissions are observed which are attributed to 2 H 11/2 , 4 S 3/2 to 4 I 15/2 and 4 F 9/2 to 4 I 15/2 transitions of Er 3+ respectively. The emission intensity is found to depend strongly on the concentration of Yb 3+ . The quadratic dependence of upconversion intensity on the excitation power indicates that the upconversion process is governed by two-photon absorption process.

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

New insights into the Kawah Ijen hydrothermal system from geophysical data

USGS Publications Warehouse

Caudron, Corentin; Mauri, G.; Williams-Jones, Glyn; Lecocq, Thomas; Syahbana, Devy Kamil; de Plaen, Raphael; Peiffer, Loic; Bernard, Alain; Saracco, Ginette

2017-01-01

Volcanoes with crater lakes and/or extensive hydrothermal systems pose significant challenges with respect to monitoring and forecasting eruptions, but they also provide new opportunities to enhance our understanding of magmatic–hydrothermal processes. Their lakes and hydrothermal systems serve as reservoirs for magmatic heat and fluid emissions, filtering and delaying the surface expressions of magmatic unrest and eruption, yet they also enable sampling and monitoring of geochemical tracers. Here, we describe the outcomes of a highly focused international experimental campaign and workshop carried out at Kawah Ijen volcano, Indonesia, in September 2014, designed to answer fundamental questions about how to improve monitoring and eruption forecasting at wet volcanoes.

Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System.

PubMed

Gomez-Saez, Gonzalo V; Pop Ristova, Petra; Sievert, Stefan M; Elvert, Marcus; Hinrichs, Kai-Uwe; Bühring, Solveig I

2017-01-01

The unique geochemistry of marine shallow-water hydrothermal systems promotes the establishment of diverse microbial communities with a range of metabolic pathways. In contrast to deep-sea vents, shallow-water vents not only support chemosynthesis, but also phototrophic primary production due to the availability of light. However, comprehensive studies targeting the predominant biogeochemical processes are rare, and consequently a holistic understanding of the functioning of these ecosystems is currently lacking. To this end, we combined stable isotope probing of lipid biomarkers with an analysis of the bacterial communities to investigate if chemoautotrophy, in parallel to photoautotrophy, plays an important role in autotrophic carbon fixation and to identify the key players. The study was carried out at a marine shallow-water hydrothermal system located at 5 m water depth off Dominica Island (Lesser Antilles), characterized by up to 55°C warm hydrothermal fluids that contain high amounts of dissolved Fe 2+ . Analysis of the bacterial diversity revealed Anaerolineae of the Chloroflexi as the most abundant bacterial class. Furthermore, the presence of key players involved in iron cycling generally known from deep-sea hydrothermal vents (e.g., Zetaproteobacteria and Geothermobacter ), supported the importance of iron-driven redox processes in this hydrothermal system. Uptake of 13 C-bicarbonate into bacterial fatty acids under light and dark conditions revealed active photo- and chemoautotrophic communities, with chemoautotrophy accounting for up to 65% of the observed autotrophic carbon fixation. Relatively increased 13 C-incorporation in the dark allowed the classification of ai C 15:0 , C 15:0 , and i C 16:0 as potential lipid biomarkers for bacterial chemoautotrophy in this ecosystem. Highest total 13 C-incorporation into fatty acids took place at the sediment surface, but chemosynthesis was found to be active down to 8 cm sediment depth. In conclusion, this study highlights the relative importance of chemoautotrophy compared to photoautotrophy in a shallow-water hydrothermal system, emphasizing chemosynthesis as a prominent process for biomass production in marine coastal environments influenced by hydrothermalism.

Relative Importance of Chemoautotrophy for Primary Production in a Light Exposed Marine Shallow Hydrothermal System

PubMed Central

Gomez-Saez, Gonzalo V.; Pop Ristova, Petra; Sievert, Stefan M.; Elvert, Marcus; Hinrichs, Kai-Uwe; Bühring, Solveig I.

2017-01-01

The unique geochemistry of marine shallow-water hydrothermal systems promotes the establishment of diverse microbial communities with a range of metabolic pathways. In contrast to deep-sea vents, shallow-water vents not only support chemosynthesis, but also phototrophic primary production due to the availability of light. However, comprehensive studies targeting the predominant biogeochemical processes are rare, and consequently a holistic understanding of the functioning of these ecosystems is currently lacking. To this end, we combined stable isotope probing of lipid biomarkers with an analysis of the bacterial communities to investigate if chemoautotrophy, in parallel to photoautotrophy, plays an important role in autotrophic carbon fixation and to identify the key players. The study was carried out at a marine shallow-water hydrothermal system located at 5 m water depth off Dominica Island (Lesser Antilles), characterized by up to 55°C warm hydrothermal fluids that contain high amounts of dissolved Fe2+. Analysis of the bacterial diversity revealed Anaerolineae of the Chloroflexi as the most abundant bacterial class. Furthermore, the presence of key players involved in iron cycling generally known from deep-sea hydrothermal vents (e.g., Zetaproteobacteria and Geothermobacter), supported the importance of iron-driven redox processes in this hydrothermal system. Uptake of 13C-bicarbonate into bacterial fatty acids under light and dark conditions revealed active photo- and chemoautotrophic communities, with chemoautotrophy accounting for up to 65% of the observed autotrophic carbon fixation. Relatively increased 13C-incorporation in the dark allowed the classification of aiC15:0, C15:0, and iC16:0 as potential lipid biomarkers for bacterial chemoautotrophy in this ecosystem. Highest total 13C-incorporation into fatty acids took place at the sediment surface, but chemosynthesis was found to be active down to 8 cm sediment depth. In conclusion, this study highlights the relative importance of chemoautotrophy compared to photoautotrophy in a shallow-water hydrothermal system, emphasizing chemosynthesis as a prominent process for biomass production in marine coastal environments influenced by hydrothermalism. PMID:28484442

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang Jilin; Shi Jianxin, E-mail: chemshijx@163.co; 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.more » 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.« less

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator.

PubMed

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

PubMed Central

Lee, Kuan-Yi

2017-01-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal–oxide–semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air. PMID:29308260

Hydrothermally synthesized PZT film grown in highly concentrated KOH solution with large electromechanical coupling coefficient for resonator

NASA Astrophysics Data System (ADS)

Feng, Guo-Hua; Lee, Kuan-Yi

2017-12-01

This paper presents a study of lead zirconate titanate (PZT) films hydrothermally grown on a dome-shaped titanium diaphragm. Few articles in the literature address the implementation of hydrothermal PZT films on curved-diaphragm substrates for resonators. In this study, a 50-μm-thick titanium sheet is embossed using balls of designed dimensions to shape a dome-shaped cavity array. Through single-process hydrothermal synthesis, PZT films are grown on both sides of the processed titanium diaphragm with good adhesion and uniformity. The hydrothermal synthesis process involves a high concentration of potassium hydroxide solution and excess amounts of lead acetate and zirconium oxychloride octahydrate. Varied deposition times and temperatures of PZT films are investigated. The grown films are characterized by X-ray diffraction and scanning electron microscopy. The 10-μm-thick PZT dome-shaped resonators with 60- and 20-μm-thick supporting layers are implemented and further tested. Results for both resonators indicate that large electromechanical coupling coefficients and a series resonance of 95 MHz from 14 MHz can be attained. The device is connected to a complementary metal-oxide-semiconductor integrated circuit for analysis of oscillator applications. The oscillator reaches a Q value of 6300 in air. The resonator exhibits a better sensing stability when loaded with water when compared with air.

Transport and deposition processes of the hydrothermal blast of the 6 August 2012 Te Maari eruption, Mt. Tongariro

NASA Astrophysics Data System (ADS)

Breard, E. C. P.; Lube, G.; Cronin, S. J.; Valentine, G. A.

2015-11-01

The 2012 eruption of Tongariro volcano (New Zealand) produced highly mobile, low-temperature, blast-derived pyroclastic density currents after partial collapse of the western flank of the Upper Te Maari crater. Despite a low volume (340,000 m3), the flows traveled up to 2.5 km from source, covering a total area of 6.1 km2. Along one of the blast axes, freshly exposed, proximal-to-distal sedimentary structures and grain-size data suggest emplacement of the fining upward tripartite depositional sequence (massive, stratified, and laminated) under a dilute and strongly longitudinally zoned turbulent density current. While the zoning formed in the deposit in the first 1500 m of runout, the current progressively waned to the extent where it transported a nearly homogenous grain-size mixture at the liftoff position. Our data indicate that after the passage of an erosive flow front, massive unit A was deposited under a rapid-suspension sedimentation regime. Unit B was deposited under a traction-dominated regime generated by a subsequent portion of the flow moving at lower velocities and with lower sediment transport capacity than the portion depositing unit A. The final and slowest flow zone deposited the finest particles under weakly tractive conditions. Transport and emplacement dynamics inferred in this study show strong similarities between hydrothermal explosions, magmatic blasts, and high-energy dilute PDCs. The common occurrence of hydrothermal fields on volcanic flanks points to this hazard being an under-appreciated one at stratovolcanoes worldwide.

Temporal change in megafauna at the Rose Garden hydrothermal vent (Galapagos Rift; eastern tropical Pacific)

NASA Astrophysics Data System (ADS)

Hessler, Robert R.; Smithey, William M.; Boudrias, Michel A.; Keller, Clifford H.; Lutz, Richard A.; Childress, James J.

1988-10-01

Hydrothermal vent communities must undergo substantial temporal change because of their dynamic physical milieu. This was verified in March 1985, when the Rose Garden hydrothermal vent on the Galapagos Rift was revisited after 5 1/4 years' absence. Comparison of photographs from the two visits revealed considerable faunal change. Among the hosts to chemoautotrophic bacteria, vestimentiferans were reduced from dominance to very low numbers. The mytilid was now extremely abundant and dominated vent openings. Vesicomyids also were more abundant. In general, vent-field suspension feeders had declined; anemones were distinctly less abundant, and siphonophores and enteropneusts were virtually absent. The decline of serpulids was likely, but less obvious. Of the mobile scavengers and carnivores, both galatheids and whelks were distincly more common. These community changes appear to result from both continuing recruitment and changes in the physical milieu. While the growth of some populations could have resulted from expanding opportunities, the population of at least one, the vesicomyid, had not achieved carrying capacity in 1979, and this could have pertained to others as well. The decrease of vestimentiferans may have been caused by declining vent-water flux, a process that would favor mytilids, or more complete vent-water filtration by the mytilids themselves. The same factors also could explain the reduction of vent-field filter feeders. These observations suggest that early stages in the cycle of Galapagos-type vent communities are likely to be dominated by vestimentiferans, but that bivalves will replace them with time.

Ca isotope fractionation and Sr/Ca partitioning associated with anhydrite formation at mid-ocean ridge hydrothermal systems: An experimental approach

NASA Astrophysics Data System (ADS)

Syverson, D. D.; Scheuermann, P.; Pester, N. J.; Higgins, J. A.; Seyfried, W. E., Jr.

2016-12-01

The elemental and isotopic mass balance of Ca and Sr between seawater and basalt at mid-ocean ridge (MOR) hydrothermal systems is an integrated reflection of the various physiochemical processes, which induce chemical exchange, in the subseafloor. Specifically, the processes of anhydrite precipitation and recrystallization are recognized to be important controls on governing the Ca and Sr elemental and isotope compositions of high temperature vent fluids, however, few experimental data exist to constrain these geochemical effects. Thus, to better understand the associated Sr/Ca partitioning and Ca isotope fractionation and rate of exchange between anhydrite and dissolved constituents, anhydrite precipitation and recrystallization experiments were performed at 175, 250, and 350°C and 500 bar at chemical conditions indicative of active MOR hydrothermal systems. The experimental data suggest that upon entrainment of seawater into MOR hydrothermal systems, anhydrite will precipitate rapidly and discriminate against the heavy isotopes of Ca (Δ44/40Ca(Anh-Fluid) = -0.68 - -0.25 ‰), whereas Sr/Ca partitioning depends on the saturation state of the evolving hydrothermal fluid with respect to anhydrite at each PTX (KD(Anh-Fluid) = 1.24 - 0.55). Coupling experimental constraints with the temperature gradient inferred for high temperature MOR hydrothermal systems in the oceanic crust, data suggest that the Ca isotope and Sr elemental composition of anhydrite formed near the seafloor will be influenced by disequilibrium effects, while, at higher temperatures further into the oceanic crust, anhydrite will be representative of equilibrium Sr/Ca partitioning and Ca isotope fractionation conditions. These experimental observations are consistent with analyzed Sr/Ca and Ca isotope compositions of anhydrites and vent fluids sampled from modern MOR hydrothermal systems1,2 and can be used to further constrain the geochemical effects of hydrothermal circulation in the oceanic crust throughout Earth's history. 1 Tivey, M. K. Generation of Seafloor Hydrothermal Deposits. Oceanography 20, 50-66 (2007).2 Amini, M. et al. Calcium isotope (δ44/40Ca) fractionation along hydrothermal pathways, Logatchev field (Mid-Atlantic Ridge, 14°45'N). Geochimica et Cosmochimica Acta 72, 4107-4122 (2008).

Numerical Simulations of Potential Gravitational Collapses of the La Soufrière de Guadeloupe Lava Dome (Lesser Antilles)

NASA Astrophysics Data System (ADS)

Mangeney, A.; Peruzzetto, M.; Rosas-Carbajal, M.; Komorowski, J. C.; Le Friant, A.; Legendre, Y.

2016-12-01

Over the past 7800 years, at least 8 partial flank collapses have occurred at La Soufrière de Guadeloupe volcano. Given a highly altered and heterogeneous dome and the presence of highly conductive acid fluid-saturated regions controlled by regional faults and listric detachment planes, this is a likely future scenario. Recent electrical tomography of the hydrothermal system constrains collapse scenarios. We developed a MATLAB interface (see figure attached) to "slice" the topography to define initial 3-D geometries and volumes (1 to 60 Mm³). We simulate the dynamics of the resulting debris avalanches as granular flows with the thin-layer depth-averaged numerical model SHALTOP. In this model, the complex rheological behavior of natural debris is simply described by an effective friction coefficient. Sensitivity analysis shows that the initial slope of the detachment plane strongly controls emplacement dynamics, causing premature arrest of the material for values lower than the friction angle, unless the collapse involves significant hydrothermal fluid that favors high mobility. In other cases, proximal topography has a predominant control over initial geometry. Indeed, the main pathways and dynamics are common to all scenarios. Friction coefficients control the final run-out distance and flow speed (up to 9km and 50m/s), but the type of friction law has little influence. Using low friction coefficients is justified by field evidence of highly mobile volcanic debris avalanches, even for relatively small volumes. In the worst case scenario tested (60 Mm³, friction angle of 8°), the material enters the sea 9 km downslope. Given the current prolonged and intensifying hydrothermal unrest at La Soufrière, and that flank instability can be triggered by seismic, hydrothermal, magmatic, and meteorologic forcing, our results have implications for risk assessment and continuing monitoring strategies on La Soufrière de Guadeloupe volcano.

Caldera unrest driven by CO2-induced drying of the deep hydrothermal system.

PubMed

Moretti, R; Troise, C; Sarno, F; De Natale, G

2018-05-29

Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO 2 -CH 4 exchange of 13 C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO 2 -rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO 2 -infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism.

Biological and environmental rhythms in (dark) deep-sea hydrothermal ecosystems

NASA Astrophysics Data System (ADS)

Cuvelier, Daphne; Legendre, Pierre; Laës-Huon, Agathe; Sarradin, Pierre-Marie; Sarrazin, Jozée

2017-06-01

During 2011, two deep-sea observatories focusing on hydrothermal vent ecology were up and running in the Atlantic (Eiffel Tower, Lucky Strike vent field) and the Northeast Pacific Ocean (NEP) (Grotto, Main Endeavour Field). Both ecological modules recorded imagery and environmental variables jointly for a time span of 23 days (7-30 October 2011) and environmental variables for up to 9 months (October 2011-June 2012). Community dynamics were assessed based on imagery analysis and rhythms in temporal variation for both fauna and environment were revealed. Tidal rhythms were found to be at play in the two settings and were most visible in temperature and tubeworm appearances (at NEP). A ˜ 6 h lag in tidal rhythm occurrence was observed between Pacific and Atlantic hydrothermal vents, which corresponds to the geographical distance and time delay between the two sites.

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 a 280 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 S 275-295 , 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. Copyright © 2017 Elsevier Ltd. All rights reserved.

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. Copyright © 2016. Published by Elsevier Ltd.

Fluid geochemistry of Fault zone hydrothermal system in the Yidun-Litang area, eastern Tibetan Plateau geothermal belt

NASA Astrophysics Data System (ADS)

Shi, Z.; Wang, G.

2017-12-01

Understanding the geochemical and geothermal characteristic of the hydrothermal systems provide useful information in appropriate evaluating the geothermal potential in this area. In this paper, we investigate the chemical and isotopic composition of thermal water in an underexploited geothermal belt, Yidun-Litang area, in eastern Tibetan Plateau geothermal belt. 24 hot springs from the Yidun and Litang area were collected and analyzed. The chemical facies of the hot springs are mainly Na-HCO3 type water. Water-rock interaction, cation exchange are the dominant hydrogeochemical processes in the hydrothermal evolution. All the hot springs show long-time water-rock interaction and significant 18O shift occurred in the Yindun area. Tritium data indicate the long-time water-rock interaction time in the hydrothermal system. According to the isotope and geochemical data, the hydrothermal systems in Yidun and Litang area may share a common deep parent geothermal liquid but receive different sources of meteoric precipitation and undergone different geochemical processes. The Yidun area have relative high reservoir equilibrium temperature (up to 230 °C) while the reservoir temperature at Litang area is relative low (up to 128 °C).

Spontaneous Ignition of Hydrothermal Flames in Supercritical Ethanol Water Solutions

NASA Technical Reports Server (NTRS)

Hicks, Michael C.; Hegde, Uday G.; Kojima, Jun J.

2017-01-01

Results are reported from recent tests where hydrothermal flames spontaneously ignited in a Supercritical Water Oxidation (SCWO) Test Cell. Hydrothermal flames are generally categorized as flames that occur when appropriate concentrations of fuel and oxidizer are present in supercritical water (SCW); i.e., water at conditions above its critical point (218 atm and 374 C). A co-flow injector was used to inject fuel, comprising an aqueous solution of 30-vol to 50-vol ethanol, and air into a reactor held at constant pressure and filled with supercritical water at approximately 240 atm and 425 C. Hydrothermal flames auto-ignited and quickly stabilized as either laminar or turbulent diffusion flames, depending on the injection velocities and test cell conditions. Two orthogonal views, one of which provided a backlit shadowgraphic image, provided visual observations. Optical emission measurements of the steady state flame were made over a spectral range spanning the ultraviolet (UV) to the near infrared (NIR) using a high-resolution, high-dynamic-range spectrometer. Depending on the fuel air flow ratios varying degrees of sooting were observed and are qualitatively compared using light absorption comparisons from backlit images.

Effects of particle size and hydro-thermal treatment of feed on performance and stomach health in fattening pigs.

PubMed

Liermann, Wendy; Berk, Andreas; Böschen, Verena; Dänicke, Sven

2015-01-01

Effects of grinding and hydro-thermal treatment of feed on growth performance, slaughter traits, nutrient digestibility, stomach content and stomach health were examined by using 96 crossbred fattening pigs. Pigs were fed a grain-soybean meal-based diet processed by various technical treatments. Feeding groups differed in particle size after grinding (finely vs. coarsely ground feed) and hydro-thermal treatment (without hydro-thermal treatment, pelleting, expanding, expanding and pelleting). Fine grinding and hydro-thermal treatment showed significant improvements on the digestibility of crude nutrients and content of metabolisable energy. Hydro-thermal treatment influenced average daily gain (ADG) and average daily feed intake (DFI) significantly. Finely ground pelleted feed without expanding enhanced performances by increasing ADG and decreasing feed-to-gain ratio (FGR) of fattening pigs. Coarsely ground feed without hydro-thermal treatment resulted in the highest ADG and DFI, however also in the highest FGR. Expanded feed decreased DFI and ADG. Slaughter traits were not affected by treatments. Coarsely ground feed without hydro-thermal treatment had protective effects on the health of gastric pars nonglandularis, however, pelleting increased gastric lesions. Hydro-thermal treatment, especially expanding, resulted in clumping of stomach content which possibly induced satiety by slower ingesta passage rate and thus decreased feed intake. Pigs fed pelleted feed showed less pronounced development of clumps in stomach content compared with expanded feed.

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

Hydrothermal carbonization: modeling, final properties design and applications: a review

USDA-ARS?s Scientific Manuscript database

Active research on biomass hydrothermal carbonization (HTC) continues to demonstrate its advantages over other thermochemical processes, in particular the interesting benefits associated with carbonaceous solid products called hydrochar (HC). The areas of applications of HC range from biofuel to dop...

Vapor-Liquid Partitioning of Iron and Manganese in Hydrothermal Fluids: An Experimental Investigation with Application to the Integrated Study of Basalt-hosted Hydrothermal Systems

NASA Astrophysics Data System (ADS)

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

2010-12-01

The chemistry of deep-sea hydrothermal vent fluids, expressed at the seafloor, reflects a complex history of physicochemical reactions. After three decades of field and experimental investigations, the processes of fluid-mineral equilibria that transform seawater into that of a typical “black smoker” are generally well described in the literature. Deep crustal fluids, when encountering a given heat source that ultimately drives hydrothermal circulation, routinely intersect the two-phase boundary. This process results in the nearly ubiquitous observations of variable salinity in vent fluids and is often a secondary driver of circulation via the evolution of a more buoyant (i.e. less saline) phase. Phase separation in chemically complex fluids results in the partitioning of dissolved species between the two evolved phases that deviates from simple charge balance calculations and these effects become more prominent with increasing temperature and/or decreasing pressure along the two-phase envelope. This process of partitioning has not been extensively studied and the interplay between the effects of phase separation and fluid-mineral equilibrium are not well understood. Most basalt-hosted hydrothermal systems appear to enter a steady state mode wherein fluids approach the heat source at depth and rise immediately once the two-phase boundary is met. Thus, venting fluids exhibit only modest deviations from seawater bulk salinity and the effects of partitioning are likely minor for all but the most volatile elements. Time series observations at integrated study sites, however, demonstrate dynamic changes in fluid chemistry following eruptions/magmatic events, including order of magnitude increases in gas concentrations and unexpectedly high Fe/Cl ratios. In this case, the time dependence of vapor-liquid partitioning relative to fluid-mineral equilibrium must be considered when attempting to interpret changes in subsurface reaction conditions. The two-phase region of vent fluids (as modeled by the NaCl-H2O system) represents challenging experimental conditions due to the extreme sensitivity to pressure and temperature. Using a novel flow through system that allows pressure and temperature to be controlled within 0.5 bars and 1°C, respectively, we have derived vapor-liquid partition coefficients for several species, including Fe and Mn. Divalent cations partition more drastically into the liquid phase than monovalent species and the demonstrated temperature sensitivity of equilibrium Fe/Mn ratios in basalt alteration experiments make these two elements excellent candidates when attempting to interpret time series changes in the aftermath of eruptions. Our experiments demonstrate that with decreasing vapor salinity, the Fe/Mn ratio can effectively double, relative to the bulk fluid composition, as the vapors approach the extremely low dissolved Cl concentrations observed at both EPR, 9°N and Main Endeavour, JdFR. Our results suggest that phase separation can easily account for the observed deviation from apparent Fe-Mn equilibrium in these fluids and further suggests that it may take more than a year for these hydrothermal systems to return to steady state.

Sub-seafloor Processes and the Composition of Diffuse Hydrothermal Fluids

NASA Astrophysics Data System (ADS)

Butterfield, D. A.; Lilley, M. D.; Huber, J. A.; Baross, J. A.

2002-12-01

High-temperature water/rock reactions create the primary hydrothermal fluids that are diluted with cool, "crustal seawater" to produce low-temperature, diffuse hydrothermal vent fluids. By knowing the composition of each of the components that combine to produce diffuse fluids, one can compare the composition of calculated mixtures with the composition of sampled fluids, and thereby infer what chemical constituents have been affected by processes other than simple conservative mixing. Although there is always uncertainty in the composition of fluids from the sub-seafloor, some processes are significant enough to alter diffuse fluid compositions from the expected conservative mixtures of hot,primary fluid and "crustal seawater." When hydrothermal vents with a wide range of temperature are sampled, processes occurring in different thermal and chemical environments potentially can be discerned. At Axial Volcano (AV) on the Juan de Fuca ridge, methane clearly is produced in warm sub-seafloor environments at temperatures of ~ 100° or less. Based on culturing and phylogenetic analysis from the same water samples at AV, hyperthermophilic methanogens are present in water samples taken from vents ranging in temperature from 15 to 78° C. Ratios of hydrogen sulfide to pseudo-conservative tracers (dissolved silica or heat) at AV decrease when primary fluids are highly diluted with oxygenated seawater. Phylogenetic signatures of microbes closely related to sulfide-oxidizers are present in these same fluids. Hydrogen sulfide oxidation represents the dominant source of energy for chemosynthesis at AV, as in most hydrothermal systems, but a relatively small proportion of the total hydrogen sulfide available is actually oxidized, except at the very lowest temperatures.

Conversion of a wet waste feedstock to biocrude by hydrothermal processing in a continuous-flow reactor: grape pomace

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, Douglas C.; Schmidt, Andrew J.; Hart, Todd R.

Wet waste feedstocks present an apt opportunity for biomass conversion to fuels by hydrothermal processing. In this study, grape pomace slurries from two varieties, Montepulciano and cabernet sauvignon, have been converted into a biocrude by hydrothermal liquefaction (HTL) in a bench-scale, continuous-flow reactor system. Carbon conversion to gravity-separable biocrude product up to 56 % was accomplished at relatively low temperature (350 C) in a pressurized (sub-critical liquid water) environment (20 MPa) when using grape pomace feedstock slurry with a 16.8 wt% concentration of dry solids processed at a liquid hourly space velocity of 2.1 h-1. Direct oil recovery was achievedmore » 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 using a Ru on C catalyst in a fixed bed producing a gas composed of methane and carbon dioxide from water soluble organics. Conversion of 99.8% of the chemical oxygen demand (COD) left in the aqueous phase was demonstrated. As a result, high conversion of grape pomace to liquid and gas fuel products was found with residual organic contamination in byproduct water reduced to <150 mg/kg COD.« less

Post-Drilling Changes in Seabed Landscape and Megabenthos in a Deep-Sea Hydrothermal System, the Iheya North Field, Okinawa Trough

PubMed Central

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, ‘artificially’ creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term. PMID:25902075

Post-drilling changes in seabed landscape and megabenthos in a deep-sea hydrothermal system, the Iheya North field, Okinawa Trough.

PubMed

Nakajima, Ryota; Yamamoto, Hiroyuki; Kawagucci, Shinsuke; Takaya, Yutaro; Nozaki, Tatsuo; Chen, Chong; Fujikura, Katsunori; Miwa, Tetsuya; Takai, Ken

2015-01-01

There has been an increasing interest in seafloor exploitation such as mineral mining in deep-sea hydrothermal fields, but the environmental impact of anthropogenic disturbance to the seafloor is poorly known. In this study, the effect of such anthropogenic disturbance by scientific drilling operations (IODP Expedition 331) on seabed landscape and megafaunal habitation was surveyed for over 3 years using remotely operated vehicle video observation in a deep-sea hydrothermal field, the Iheya North field, in the Okinawa Trough. We focused on observations from a particular drilling site (Site C0014) where the most dynamic change of landscape and megafaunal habitation was observed among the drilling sites of IODP Exp. 331. No visible hydrothermal fluid discharge had been observed at the sedimentary seafloor at Site C0014, where Calyptogena clam colonies were known for more than 10 years, before the drilling event. After drilling commenced, the original Calyptogena colonies were completely buried by the drilling deposits. Several months after the drilling, diffusing high-temperature hydrothermal fluid began to discharge from the sedimentary subseafloor in the area of over 20 m from the drill holes, 'artificially' creating a new hydrothermal vent habitat. Widespread microbial mats developed on the seafloor with the diffusing hydrothermal fluids and the galatheid crab Shinkaia crosnieri endemic to vents dominated the new vent community. The previously soft, sedimentary seafloor was hardened probably due to barite/gypsum mineralization or silicification, becoming rough and undulated with many fissures after the drilling operation. Although the effects of the drilling operation on seabed landscape and megafaunal composition are probably confined to an area of maximally 30 m from the drill holes, the newly established hydrothermal vent ecosystem has already lasted 2 years and is like to continue to exist until the fluid discharge ceases and thus the ecosystem in the area has been altered for long-term.

Bench-Scale Evaluation of Hydrothermal Processing Technology for Conversion of Wastewater Solids to Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marrone, Philip A.; Elliott, Douglas C.; Billing, Justin M.

Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of hydrothermal treatment for handling municipal wastewater sludge. HTL tests were conducted at 300-350°C and 20 MPa on three different feeds: primary sludge, secondary sludge, and digested solids. Corresponding CHG tests were conducted at 350°C and 20 MPa on the HTL aqueous phase output using a ruthenium based catalyst. Biocrude yields ranged from 25-37%. Biocrude composition and quality were comparable to biocrudes generated from algae feeds. Subsequent hydrotreating of biocrude resulted in a product with comparable physical and chemical properties to crude oil.more » CHG product gas methane yields on a carbon basis ranged from 47-64%. Siloxane concentrations in the CHG product gas were below engine limits. The HTL-CHG process resulted in a chemical oxygen demand (COD) reduction of > 99.9% and a reduction in residual solids for disposal of 94-99%.« less

Mesophilic-hydrothermal-thermophilic (M-H-T) digestion of green corn straw.

PubMed

Li, Dong; Wang, Qingjing; Li, Jiang; Li, Zhidong; Yuan, Yuexiang; Yan, Zhiying; Mei, Zili; Liu, Xiaofeng

2016-02-01

Mesophilic-hydrothermal (80-160 °C, 30 min)-thermophilic (M-H-T) digestion and control tests of mesophilic (M), thermophilic (T), hydrothermal-mesophilic (H-M), and mesophilic-thermophilic digestion (M-T) of green corn straw were conducted for a 20-day fermentation period. The results indicate that M-H-T is an efficient method to improve methane production. A maximum methane yield of 371.74 mL/g volatile solid was obtained by the M (3 days)-H (140 °C)-T (17 days) process, which was 20.44%, 16.55%, 31.44%, and 14.31% higher than the yields of the M, T, 140-M, and M-T processes. The enhanced methane production was attributed to (1) the improved hemicellulose degradation and lignin disorganization; (2) prevention of the degradation of soluble sugar, easily hydrolyzed hemicellulose and cellulose into furfural and methylfurfural; and (3) lack of formation of Maillard reaction products during initial hydrothermal treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

A colluvium - travertine sedimentary succession from the Tibetan Plateau: dating and climatic significance

NASA Astrophysics Data System (ADS)

Meyer, Michael; Wang, Zhijun; Schlütz, Frank; Hoffmann, Dirk; May, Jan-Hendrik; Aldenderfer, Mark

2014-05-01

Morphodynamics and sedimentation on the Tibetan Plateau are strongly controlled by cold-arid climate conditions and distinct freeze-thaw cycles. In such a periglacial environment mass-wasting processes are dominant on mountain slopes, causing thick successions of talus and colluvium to accumulate. While periglacial slope dynamics are ubiquitous on the plateau today, they were probably much more intense during the various cold stages of the Late Pleistocene. However, the exact nature as well as the timing and duration of such temperature controlled slope dynamics on the Tibetan plateau are not well constrained. Travertines are secondary carbonates precipitated from hydrothermal springs. On the Tibetan Plateau these types of spring deposits form along neotectonic faults, where super-saturated ground water can penetrate onto the surface, facilitating degassing and carbonate precipitation. Spring carbonate formation further requires non-permanently frozen ground and reasonable humid conditions in order to recharge the ground water aquifer. Travertines hold potential for palaeoenvironmental reconstruction, because they are dateable via U-series techniques and their geochemical, biological and petrographic signature can be used to extract high resolution palaeoenvironmental information. Due to a dense network of neotectonic faults on the Tibetan plateau, travertines are relatively common. Nevertheless, the potential of these hydrothermal spring deposits as an archive for palaeoenvironmental change on the plateau has yet to be explored. Here we present the first results obtained for an unusual, non-continuous sediment sequence encountered in southern Tibet at an altitude of 4200 m asl. near Chusang village, i.e. a ca. 200 m thick succession of periglacial colluvium alternating with travertine deposits. Preliminary data indicate that travertine deposition at the Chusang hydrothermal spring occurred periodically throughout the Late Pleistocene and extensive travertine precipitation was also responsible for preserving old colluvial sediment. We combine U-series disequilibrium dating with optically stimulated luminescence dating and radiocarbon dating to constrain the depositional history of this unique sediment sequence. Sedimentological logging and geomorphological mapping is used to understand past depositional processes and environmental constraints. Comparison to published high resolution climate records that are continuous in nature (e.g. speleothem records from adjacent catchments and regions) will allow us to link this clastic-chemical sediment sequence into the broader palaeoclimatic framework of High Asia.

Very high expander processing of maize on animal performance, digestibility and product quality of finishing pigs and broilers.

PubMed

Puntigam, R; Schedle, K; Schwarz, C; Wanzenböck, E; Eipper, J; Lechner, E-M; Yin, L; Gierus, M

2018-07-01

The present study investigated the effect of hydrothermic maize processing and supplementation of amino acids (AA) in two experiments. In total, 60 barrows and 384 broilers were fed four diets including either unprocessed (T1), or hydrothermically processed maize, that is short- (T2), or long-term conditioned (LC) (T3), and subsequently expanded maize of the same batch. Assuming a higher metabolizable energy (ME) content after processing, the fourth diet (T4) contains maize processed as treatment T3, but AA were supplemented to maintain the ideal protein value. Performance, digestibility and product quality in both species were assessed. Results show that in pigs receiving T4 the average daily feed intake was lower compared with the other treatments, whereas no difference was observed in broilers. The T3 improved the feed conversion rate compared with T1 (P<0.10) for both species. In contrast, average daily gain (ADG) (1277 g/day for T2 and 1267 g/day for T3 v. 971 g/day for T1) was only altered in pigs. The hydrothermic maize processing increased the apparent total tract digestibility (ATTD) of dry matter, starch and ether extract after acid hydrolysis. This may be a consequence of higher ATTD of gross energy in the finishing phase for both animal species, suggesting a higher ME content in diets with processed maize. The higher ME content of diets with processed maize is supported also by measurements of product quality. Supplementation of AA in T4 enhanced the loin depth in pigs as well as the amount of breast meat in broilers. Further effects of processing maize on meat quality were the reduced yellowness and antioxidative capacity (P<0.10) for broilers, likely due to the heat damage of xanthophylls and tocopherols. Processing also increased springiness and chewiness (P<0.10) of the broilers breast meat, whereas the loin meat of pigs showed a decreased lightness and yellowness (P<0.10) in meat when hydrothermic processed maize was used (for T2, T3 and T4). LC processed maize (T3) showed the lowest springiness in pork, however the supplementation of AA in T4 did not show differences between the treatments. Shown results demonstrated positive effects of hydrothermic processing of maize on animal performance and digestibility in both species. However, effects on carcass characteristics and product quality differed. The negative effects on product quality could be partly compensated with the AA supplementation, whereas a change in meat colour and reduced antioxidative capacity was observed in all groups fed hydrothermic maize processing.

Sol-gel (template) synthesis of macroporous Mo-based catalysts for hydrothermal oxidation of radionuclide-organic complexes

NASA Astrophysics Data System (ADS)

Papynov, E. K.; Palamarchuk, M. S.; Mayorov, V. Yu; Modin, E. B.; Portnyagin, A. S.; Sokol'nitskaya, T. A.; Belov, A. A.; Tananaev, I. G.; Avramenko, V. A.

2017-07-01

Molybdenum compounds are industrially demanding as heterogeneous catalysts for oxidation of various organic substances. Highly porous structure of molybdenum-containing catalysts avoids surface's colmatation and prevents blocking catalytic sites that makes these materials play a key role in processes of hydrothermal oxidation of radionuclide organic complexes. The study presents an original way of sol-gel synthesis of new macroporous molybdenum compounds using ;core-shell; colloid template (polymer latex) as poreforming agent. We have described three individual routs of template removal via thermal decomposition to obtain porous materials based on molybdenum compounds. Thermal treatment conditions (temperature, gaseous atmosphere) have been studied with respect to their influence on composition, structure and catalytic properties of synthesized molybdenum systems. The optimal way to synthesis of crystal molybdenum (VI) oxide with ordered porous structure (mean pore size 100-160 nm) has been suggested. Catalytic properties of macroporous molybdenum materials have been investigated in the process of liquid phase and hydrothermal oxidation of such organic substances thiazine and stable Co-EDTA complex. It was shown that macroporous molybdenum oxides could be applied as prospective catalysts for hydrothermal oxidation of organic radionuclide complexes during the processing of radioactive waste.

Hydrothermal Venting at Hinepuia Submarine Volcano, Kermadec Arc: Understanding Magmatic-Hydrothermal Fluid Chemistry

NASA Astrophysics Data System (ADS)

Stucker, Valerie K.; Walker, Sharon L.; de Ronde, Cornel E. J.; Caratori Tontini, Fabio; Tsuchida, Shinji

2017-10-01

The Hinepuia volcanic center is made up of two distinct edifices aligned northwest to southeast, with an active cone complex in the SE. Hinepuia is one of several active volcanoes in the northern segment of the Kermadec arc. Regional magnetic data show no evidence for large-scale hydrothermal alteration at Hinepuia, yet plume data confirm present-day hydrothermal discharge, suggesting that the hydrothermal system may be too young to have altered the host rocks with respect to measurable changes in magnetic signal. Gravity data are consistent with crustal thinning and shallow mantle under the volcanic center. Following the discovery of hydrothermal plumes over Hinepuia, the submersible Shinkai 6500 was used to explore the SE cone and sample hydrothermal fluids. The chemistry of hydrothermal fluids from submarine arc and backarc volcanoes is typically dominated by water-rock interactions and/or magmatic degassing. Chemical analyses of vent fluids show that Hinepuia does not quite fit either traditional model. Moreover, the Hinepuia samples fall between those typically ascribed to both end-member fluid types when plotted on a K-Mg-SO4 ternary diagram. Due to evidence of strong degassing, abundant native sulfur deposition, and H2S presence, the vent sampled at Hinepuia is ultimately classified as a magmatic-hydrothermal system with a water-rock influence. This vent is releasing water vapor and magmatic volatiles with a notable lack of salinity due to subcritical boiling and phase separation. Magmatic-hydrothermal fluid chemistry appears to be controlled by a combination of gas flux, phase separation processes, and volcano evolution and/or distance from the magma source.

Iridium material for hydrothermal oxidation environments

DOEpatents

Hong, Glenn T.; Zilberstein, Vladimir A.

1996-01-01

A process for hydrothermal oxidation of combustible materials in which, during at least a part of the oxidation, corrosive material is present and makes contact with at least a portion of the apparatus over a contact area on the apparatus. At least a portion of the contact surface area comprises iridium, iridium oxide, an iridium alloy, or a base metal overlaid with an iridium coating. Iridium has been found to be highly resistant to environments encountered in the process of hydrothermal oxidation. Such environments typically contain greater than 50 mole percent water, together with oxygen, carbon dioxide, and a wide range of acids, bases and salts. Pressures are typically about 27.5 to about 1000 bar while temperatures range as high as 800.degree. C.

Niobium oxide synthesized via etching agent - assisted hydrothermal process: A films with low reflectance properties

NASA Astrophysics Data System (ADS)

Rani, Rozina Abdul; Zoolfakar, Ahmad Sabirin; Alrokayan, Salman; Khan, Haseeb; Rusop, M.

2018-05-01

In this paper, synthesis of the hydrothermal based etching process of niobium oxide (Nb2O5) films and their reflectance properties are presented. The concentration of etching agent, which is ammonium fluoride (NH4F) in the hydrothermal solution as well as the grain size and the annealing condition have significantly affected the reflectance properties of Nb2O5 films. Films that synthesized in 1.65M of NH4F solution showed the lowest percentage of reflectance value of 3.22% at 222 nm. The obtained reflectance results have shown that this kind of Nb2O5 films is very suitable for anti-reflective coating layer and UV sensor application.

Merging genomes with geochemistry in hydrothermal ecosystems.

PubMed

Reysenbach, Anna-Louise; Shock, Everett

2002-05-10

Thermophilic microbial inhabitants of active seafloor and continental hot springs populate the deepest branches of the universal phylogenetic tree, making hydrothermal ecosystems the most ancient continuously inhabited ecosystems on Earth. Geochemical consequences of hot water-rock interactions render these environments habitable and supply a diverse array of energy sources. Clues to the strategies for how life thrives in these dynamic ecosystems are beginning to be elucidated through a confluence of biogeochemistry, microbiology, ecology, molecular biology, and genomics. These efforts have the potential to reveal how ecosystems originate, the extent of the subsurface biosphere, and the driving forces of evolution.

Assessing the environmental impact of energy production from hydrochar generated via hydrothermal carbonization waste management

USDA-ARS?s Scientific Manuscript database

Hydrothermal carbonization (HTC) is a relatively low temperature thermal conversion process that is gaining significant attention as a sustainable and environmentally beneficial approach for the transformation of biomass and waste streams to value-added products. Although there are numerous studies ...

Hydrothermal processing of biomass from invasive aquatic plants

Treesearch

W. James Catallo; Todd F. Shupe; Thomas L. Eberhardt

2008-01-01

The purpose of this study was to examine the hydrothermal (HT) treatment of three invasive aquatic plants (i.e., Lemna sp., Hydrilla sp., and Eichhornia sp.) with respect to the generation of semi-volatile hydrocarbon product mixtures and biomass volume reduction. Identical HT treatments yielded similar semi-...

The Antibacterial Polyamide 6-ZnO Hierarchical Nanofibers Fabricated by Atomic Layer Deposition and Hydrothermal Growth

NASA Astrophysics Data System (ADS)

Wang, Zhengduo; Zhang, Li; Liu, Zhongwei; Sang, Lijun; Yang, Lizhen; Chen, Qiang

2017-06-01

In this paper, we report the combination of atomic layer deposition (ALD) with hydrothermal techniques to deposit ZnO on electrospun polyamide 6 (PA 6) nanofiber (NF) surface in the purpose of antibacterial application. The micro- and nanostructures of the hierarchical fibers are characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), and scanning transmission electron microscopy (STEM). We find that NFs can grow into "water lily"- and "caterpillar"-like shapes, which depend on the number of ALD cycles and the hydrothermal reaction period. It is believed that the thickness of ZnO seed layer by ALD process and the period in hydrothermal reaction have the same importance in crystalline growth and hierarchical fiber formation. The tests of antibacterial activity demonstrate that the ZnO/PA 6 core-shell composite fabricated by the combination of ALD with hydrothermal are markedly efficient in suppressing bacteria survivorship.

Enhanced hydrothermal stability of Cu-ZSM-5 catalyst via surface modification in the selective catalytic reduction of NO with NH3

NASA Astrophysics Data System (ADS)

Zhang, Tao; Shi, Juan; Liu, Jian; Wang, Daxi; Zhao, Zhen; Cheng, Kai; Li, Jianmei

2016-07-01

The surface of Cu-ZSM-5 catalyst was modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) for enhancing its hydrothermal stability in the selective catalytic reduction of NO with NH3. After hydrothermal aging at 750 °C for 13 h, the catalytic performance of Cu-ZSM-5-Aged catalyst was significantly reduced for NO reduction in the entire temperature range, while that of Cu-ZSM-5-CLD-Aged catalyst was affected very little. The characterization results indicated that an inert silica layer was deposited on the surface of Cu-ZSM-5 and formed a protective layer, which prevents the detachment of Cu2+ from ZSM-5 ion-exchange positions and the dealumination of zeolite during the hydrothermal aging process. Based on the data it is hypothesized to be the primary reason for the high hydrothermal stability of Cu-ZSM-5-CLD catalyst.

The effects of cathodic micro-voltage combined with hydrothermal pretreatment on methane fermentation of lignocellulose substrate

NASA Astrophysics Data System (ADS)

Liu, Dianxin; Ning, Ping; Qu, Guangfei; Huang, Xi; Liu, Yuhuan; Zhang, Jian

2017-05-01

The methane fermentation study assisted with cathodic micro-voltage was carried out to investigate the electric field effects on the fermentation of hydrothermally pretreated lignocellulose substrate. It was illustrated that a 0.25V cathode voltage and hydrothermal pretreatment could improve the biogas production, biogas quality and lignocellulose degradation ratio significantly. The cumulative biogas productions in the fermentation of hydrothermally pretreated cow dungs at 50°C, 150°C and 200°C with a 0.25V cathode voltage were observed in a total of 6640mL, 9218mL and 9456mL respectively over a detention time of 33 days. In comparison with the fermentation pretreated at 200°C without any voltage, nearly doubled of cumulative biogas production was obtained in the process of cathode-assisted fermentation. It was also observed that the daily methane content greater than or equal to 70% in the biogas generated with cathode voltage were clearly greater than that without voltages. Furthermore, the fermentation applied with a 0.25V cathode voltage had resulted into significant increases of 12.64% and 9.44% in lignin and cellulose degradation ratio relative to voltage free fermentation. And in the process of fermentation applied with cathode voltage, the final lignocellulose degradation ratio increased with the hydrothermal pretreatment temperature. Thus, the hydrothermal pretreatment and assisting fermentation with low cathode voltage can effectively promote the lignocellulose degradation. All results revealed that cathodic micro-voltage combined with hydrothermal pretreatment can remarkably improve the fermentation of lignocellulosic materials, indicating that a more effective fermentation technology can be developed by applying with cathodic micro-voltage.

Metagenomic resolution of microbial functions in deep-sea hydrothermal plumes across the Eastern Lau Spreading Center.

PubMed

Anantharaman, Karthik; Breier, John A; Dick, Gregory J

2016-01-01

Microbial processes within deep-sea hydrothermal plumes affect ocean biogeochemistry on global scales. In rising hydrothermal plumes, a combination of microbial metabolism and particle formation processes initiate the transformation of reduced chemicals like hydrogen sulfide, hydrogen, methane, iron, manganese and ammonia that are abundant in hydrothermal vent fluids. Despite the biogeochemical importance of this rising portion of plumes, it is understudied in comparison to neutrally buoyant plumes. Here we use metagenomics and bioenergetic modeling to describe the abundance and genetic potential of microorganisms in relation to available electron donors in five different hydrothermal plumes and three associated background deep-sea waters from the Eastern Lau Spreading Center located in the Western Pacific Ocean. Three hundred and thirty one distinct genomic 'bins' were identified, comprising an estimated 951 genomes of archaea, bacteria, eukarya and viruses. A significant proportion of these genomes is from novel microorganisms and thus reveals insights into the energy metabolism of heretofore unknown microbial groups. Community-wide analyses of genes encoding enzymes that oxidize inorganic energy sources showed that sulfur oxidation was the most abundant and diverse chemolithotrophic microbial metabolism in the community. Genes for sulfur oxidation were commonly present in genomic bins that also contained genes for oxidation of hydrogen and methane, suggesting metabolic versatility in these microbial groups. The relative diversity and abundance of genes encoding hydrogen oxidation was moderate, whereas that of genes for methane and ammonia oxidation was low in comparison to sulfur oxidation. Bioenergetic-thermodynamic modeling supports the metagenomic analyses, showing that oxidation of elemental sulfur with oxygen is the most dominant catabolic reaction in the hydrothermal plumes. We conclude that the energy metabolism of microbial communities inhabiting rising hydrothermal plumes is dictated by the underlying plume chemistry, with a dominant role for sulfur-based chemolithoautotrophy.

Microdistribution of Faunal Assemblages at Deep-Sea Hydrothermal Vents in the Southern Ocean

PubMed Central

Marsh, Leigh; Copley, Jonathan T.; Huvenne, Veerle A. I.; Linse, Katrin; Reid, William D. K.; Rogers, Alex D.; Sweeting, Christopher J.; Tyler, Paul A.

2012-01-01

Chemosynthetic primary production by microbes supports abundant faunal assemblages at deep-sea hydrothermal vents, with zonation of invertebrate species typically occurring along physico-chemical gradients. Recently discovered vent fields on the East Scotia Ridge (ESR) in the Southern Ocean represent a new province of vent biogeography, but the spatial dynamics of their distinct fauna have yet to be elucidated. This study determines patterns of faunal zonation, species associations, and relationships between faunal microdistribution and hydrothermal activity in a vent field at a depth of 2,400 m on the ESR. Remotely operated vehicle (ROV) dives obtained high-definition imagery of three chimney structures with varying levels of hydrothermal activity, and a mosaic image of >250 m2 of seafloor co-registered with temperature measurements. Analysis of faunal microdistribution within the mosaiced seafloor reveals a consistent pattern of faunal zonation with increasing distance from vent sources and peak temperatures. Assemblages closest to vent sources are visibly dominated by a new species of anomuran crab, Kiwa n. sp. (abundance >700 individuals m−2), followed by a peltospiroid gastropod (>1,500 individuals m−2), eolepadid barnacle (>1,500 individuals m−2), and carnivorous actinostolid anemone (>30 individuals m−2). Peripheral fauna are not dominated by a single taxon, but include predatory and scavenger taxa such as stichasterid seastars, pycnogonids and octopus. Variation in faunal microdistribution on chimneys with differing levels of activity suggests a possible successional sequence for vent fauna in this new biogeographic province. An increase in δ34S values of primary consumers with distance from vent sources, and variation in their δ13C values also indicate possible zonation of nutritional modes of the vent fauna. By using ROV videography to obtain a high-resolution representation of a vent environment over a greater extent than previous studies, these results provide a baseline for determining temporal change and investigations of processes structuring faunal assemblages at Southern Ocean vents. PMID:23144754

Exceptional discovery of a shallow-water hydrothermal site in the SW area of Basiluzzo islet (Aeolian archipelago, South Tyrrhenian Sea): An environment to preserve

PubMed Central

Andaloro, Franco; Canese, Simonepietro; Bo, Marzia; Di Bella, Marcella; Italiano, Francesco; Sabatino, Giuseppe; Battaglia, Pietro; Consoli, Pierpaolo; Giordano, Patrizia; Spagnoli, Federico; La Cono, Violetta; Yakimov, Michail M.; Scotti, Gianfranco; Romeo, Teresa

2018-01-01

The geological, biological and geochemical features of a particular field of hydrothermal vents, discovered in the Panarea Volcanic Complex during a research survey carried out in 2015, are described for the first time. The site, located at 70–80 m depth off the South-western coast of the islet of Basiluzzo, was named Smoking Land for the presence of a large number of wide and high active chimneys and was characterized in terms of dissolved benthic fluxes, associated macrofauna and megafauna communities and preliminary mineralogy and geochemistry of chimney structures. On the whole field, a total of 39 chimneys, different in size and shape, were closely observed and described; 14 of them showed emission of low temperature hydrothermal fluids of marine origin characterized by acidified chemical conditions. The CTD and benthic chamber measurements highlighted that the Smoking Land is able to form a sea water bottom layer characterized by variable acidity and high DIC and trace elements concentrations; these characteristics weaken moving away from the chimney mouths. The SEM-EDS analysis of the collected solid samples revealed a chimney structure principally composed by amorphous and low crystalline Fe-oxyhydroxides of hydrothermal origins. The ROV explorations revealed a wide coverage of red algae (Peyssonnelia spp.) colonized by the green algae Flabiella petiolata and by suspension feeders, mainly sponges, but also bryozoans, and tubicolous polychaetes. Although novent-exclusive species were identified, the benthic communities found in association to the chimneys included more taxa than those observed in the surrounding no-vent rocky areas. These first findings evidence a submarine dynamic habitat where geological, chemical and biological processes are intimately connected, making the Smoking Land an important site in terms of marine heritage that should be safeguarded and protected. PMID:29300784

2-D hydro-viscoelastic model for convective drying of deformable and unsaturated porous material

NASA Astrophysics Data System (ADS)

Hassini, Lamine; Raja, Lamloumi; Lecompte-Nana, Gisèle Laure; Elcafsi, Mohamed Afif

2017-04-01

The aim of this work was to simulate in two dimensions the spatio-temporal evolution of the moisture content, the temperature, the solid (dry matter) concentration, the dry product total porosity, the gas porosity, and the mechanical stress within a deformable and unsaturated product during convective drying. The material under study was an elongated cellulose-clay composite sample with a square section placed in hot air flow. Currently, this innovative composite is used in the processing of boxes devoted to the preservation of heritage and precious objects against fire damage and other degradation (moisture, insects, etc.). A comprehensive and rigorous hydrothermal model had been merged with a dynamic linear viscoelasticity model based on Bishop's effective stress theory, assuming that the stress tensor is the sum of solid, liquid, and gas stresses. The material viscoelastic properties were measured by means of stress relaxation tests for different water contents. The viscoelastic behaviour was described by a generalized Maxwell model whose parameters were correlated to the water content. The equations of our model were solved by means of the 'COMSOL Multiphysics' software. The hydrothermal part of the model was validated by comparison with experimental drying curves obtained in a laboratory hot-air dryer. The simulations of the spatio-temporal distributions of mechanical stress were performed and interpreted in terms of material potential damage. The sample shape was also predicted all over the drying process.

[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.

Evolution of Morphology and Crystallinity of Silica Minerals Under Hydrothermal Conditions

NASA Astrophysics Data System (ADS)

Isobe, H.

2011-12-01

Silica minerals are quite common mineral species in surface environment of the terrestrial planets. They are good indicator of terrestrial processes including hydrothermal alteration, diagenesis and soil formation. Hydrothermal quartz, metastable low temperature cristobalite and amorphous silica show characteristic morphology and crystallinity depending on their formation processes and kinetics under wide range of temperature, pressure, acidity and thermal history. In this study, silica minerals produced by acidic hydrothermal alteration related to volcanic activities and hydrothermal crystallization experiments from diatom sediment are examined with crystallographic analysis and morphologic observations. Low temperature form of cistobalite is a metastable phase and a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal / volcanic areas. XRD analysis revealed that the alteration degree of whole rock is represented by abundance of cristobalite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Shorter d-spacing and narrower FWHM cristobalite crystallize from precursor materials with less-crystallized, longer d-spacing and wider FWHM cristobalite. Textures of hydrothermal cristobalite in altered rock shows remnant of porphylitic texture of the host rock, pyroxene-amphibole andesite. Diatom has amorphous silica shell and makes diatomite sediment. Diatomite found in less diagenetic Quarternary formation keeps amorphous silica diatom shells. Hydrothermal alteration experiments of amorphous silica diatomite sediment are carried out from 300 °C to 550 °C. Mineral composition of run products shows crystallization of cristobalite and quartz progress depending on temperature and run durations. Initial crystallization product, cristobalite grains occur as characteristic lepispheres and granules with various surface structures. At the very initial stage of cristobalite crystallization within 2 days run duration, cristobalite shows lepispheres a few micron meters in diameter with irregular, submicron scale ridges and grooves on the surface. With the run duration up to 7 days, lepispheres change to granules with smooth surface remaining a few micron meters in diameter. Crystallinity of cristobalite lepispheres and granules corresponds to opal-CT. Euhedral quartz crystals grow with dissolution of cristobalite grains. Growth rate of cristobalite and quartz is controlled by crystallization kinetics with induction period strongly depending on temperature. Induction period of cristobalite crystallization from amorphous silica may exceed several million years at temperature below 100 °C. Crystallinity, morphology and growth rate of silica minerals occurred in various terrestrial and planetary processes are controlled by temperature and acidity of hydrothermal fluid and nucleation and growth kinetics of silica minerals.

Phreatic activity and hydrothermal alteration in the Valley of Desolation, Dominica, Lesser Antilles

NASA Astrophysics Data System (ADS)

Mayer, Klaus; Scheu, Bettina; Yilmaz, Tim I.; Montanaro, Cristian; Albert Gilg, H.; Rott, Stefanie; Joseph, Erouscilla P.; Dingwell, Donald B.

2017-12-01

Phreatic eruptions are possibly the most dramatic surface expressions of hydrothermal activity, and they remain poorly understood. The near absence of precursory signals makes phreatic eruptions unpredictable with respect to both time and magnitude. The Valley of Desolation (VoD), Dominica, located close to the Boiling Lake, the second largest high-temperature volcanic crater lake in the world, hosts vigorous hydrothermal activity with hot springs, mud pools, fumaroles, and steaming ground. A phreatic or phreatomagmatic eruption from this site is considered to be the most likely scenario for future volcanic activity on Dominica. Yet there is little information regarding the trigger mechanisms and eruption processes of explosive events at this active hydrothermal center, and only a very small number of studies have investigated hydrothermal activity in the VoD. We therefore conducted two field campaigns in the VoD to map hydrothermal activity and its surficial phenomena. We also investigated alteration processes and their effects on degassing and phreatic eruption processes. We collected in situ petrophysical properties of clay-rich unconsolidated samples, and together with consolidated rock samples, we investigated the range of supergene and hydrothermal alteration in the laboratory. In addition, we performed rapid decompression experiments on unconsolidated soil samples. Our results show that alteration leads to an increasing abundance of clay minerals and a decrease in both strength and permeability of the rocks. In the immediate vicinity of degassing acid-sulfate fluids, advanced argillic alteration yields a mineral zoning which is influenced by meteoric water. The water-saturated basal zone is dominated by kaolinite run 0whereas alunite formation is favored at and above the groundwater table where atmospheric oxidation of H2S to H2SO4 occurs (e.g., steam-heated alteration). Alteration effects may in turn inhibit degassing at the surface, increasing the potential for pressurization in the subsurface and thus lead to phreatic eruptions. Rapid decompression experiments, together with ballistic trajectory calculations, constrain estimates of the conditions prior to the 1997 small-scale phreatic event in the VoD. The results presented here may serve as a contribution to the understanding of the hazard potential of ongoing hydrothermal activity within the VoD. On a broader perspective, our results will help evaluate hydrothermal activity in similar areas worldwide which might also have the potential for phreatic eruptions, for instance Poas (Costa Rica) or Tongariro and Waimangu (New Zealand).

Impact of two hydrothermal carbonization filtrates on soil greenhouse production

USDA-ARS?s Scientific Manuscript database

Hydrothermal carbonization (HTC) is a thermochemical treatment process that allows for the conversion of wet biomass slurries to new liquid and solid products. A majority of the research to date has focused on the solid HTC product (hydrochar). Less attention has been paid to the utilization of the ...

Episodic thermal perturbations associated with groundwater flow: An example from Kilauea Volcano, Hawaii

USGS Publications Warehouse

Hurwitz, S.; Ingebritsen, S.E.; Sorey, M.L.

2002-01-01

Temperature measurements in deep drill holes on volcano summits or upper flanks allow a quantitative analysis of groundwater induced heat transport within the edifice. We present a new temperature-depth profile from a deep well on the summit of Kilauea Volcano, Hawaii, and analyze it in conjunction with a temperature profile measured 26 years earlier. We propose two groundwater flow models to interpret the complex temperature profiles. The first is a modified confined lateral flow model (CLFM) with a continuous flux of hydrothermal fluid. In the second, transient flow model (TFM), slow conductive cooling follows a brief, advective heating event. We carry out numerical simulations to examine the timescales associated with each of the models. Results for both models are sensitive to the initial conditions, and with realistic initial conditions it takes between 750 and 1000 simulation years for either model to match the measured temperature profiles. With somewhat hotter initial conditions, results are consistent with onset of a hydrothermal plume ???550 years ago, coincident with initiation of caldera subsidence. We show that the TFM is consistent with other data from hydrothermal systems and laboratory experiments and perhaps is more appropriate for this highly dynamic environment. The TFM implies that volcano-hydrothermal systems may be dominated by episodic events and that thermal perturbations may persist for several thousand years after hydrothermal flow has ceased.

A ubiquitous thermoacidophilic archaeon from deep-sea hydrothermal vents

USGS Publications Warehouse

Reysenbach, A.-L.; Liu, Yajing; Banta, A.B.; Beveridge, T.J.; Kirshtein, J.D.; Schouten, S.; Tivey, M.K.; Von Damm, Karen L.; Voytek, M.A.

2006-01-01

Deep-sea hydrothermal vents are important in global biogeochemical cycles, providing biological oases at the sea floor that are supported by the thermal and chemical flux from the Earth's interior. As hot, acidic and reduced hydrothermal fluids mix with cold, alkaline and oxygenated sea water, minerals precipitate to form porous sulphide-sulphate deposits. These structures provide microhabitats for a diversity of prokaryotes that exploit the geochemical and physical gradients in this dynamic ecosystem. It has been proposed that fluid pH in the actively venting sulphide structures is generally low (pH < 4.5), yet no extreme thermoacidophile has been isolated from vent deposits. Culture-independent surveys based on ribosomal RNA genes from deep-sea hydrothermal deposits have identified a widespread euryarchaeotal lineage, DHVE2 (deep-sea hydrothermal vent euryarchaeotic 2). Despite the ubiquity and apparent deep-sea endemism of DHVE2, cultivation of this group has been unsuccessful and thus its metabolism remains a mystery. Here we report the isolation and cultivation of a member of the DHVE2 group, which is an obligate thermoacidophilic sulphur- or iron-reducing heterotroph capable of growing from pH 3.3 to 5.8 and between 55 and 75??C. In addition, we demonstrate that this isolate constitutes up to 15% of the archaeal population, providing evidence that thermoacidophiles may be key players in the sulphur and iron cycling at deep-sea vents. ?? 2006 Nature Publishing Group.

Laboratory simulated hydrothermal alteration of sedimentary organic matter from Guaymas Basin, Gulf of California. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Leif, Roald N.

1993-01-01

High temperature alteration of sedimentary organic matter associated with marine hydrothermal systems involves complex physical and chemical processes that are not easily measured in most natural systems. Many of these processes can be evaluated indirectly by examining the geochemistry of the hydrothermal system in the laboratory. In this investigation, an experimental organic geochemical approach to studying pyrolysis of sedimentary organic matter is applied to the hydrothermal system in the Guaymas Basin, Gulf of California. A general survey of hydrothermal oils and extractable organic matter (bitumen) in hydrothermally altered sediments identified several homologous series of alkanones associated with a high temperature hydrothermal origin. The alkanones range in carbon number from C11 to C30 with no carbon number preference. Alkan-2-ones are in highest concentrations, with lower amounts of 3-, 4-, 5- (and higher) homologs. The alkanones appear to be pyrolysis products synthesized under extreme hydrothermal conditions. Hydrous pyrolysis and confinement pyrolysis experiments were performed to simulate thermally enhanced diagenetic and catagenetic changes in the immature sedimentary organic matter. The extent of alteration was measured by monitoring the n-alkanes, acyclic isoprenoids, steroid and triterpenoid biomarkers, polycyclic aromatic hydrocarbons and alkanones. The results were compared to bitumen extracts from sediments which have been naturally altered by a sill intrusion and accompanied hydrothermal fluid flow. These pyrolysis experiments duplicated many of the organic matter transformations observed in the natural system. Full hopane and sterane maturation occurred after 48 hr in experiments at 330 deg C with low water/rock mass ratios (0.29). A variety of radical and ionic reactions are responsible for the organic compound conversions which occur under extreme hydrothermal conditions. Short duration pyrolysis experiments revealed that a portion of the hydrocarbons generated from kerogen was observed to go through alkene intermediates, and the rate of alkene isomerization was influenced by the ionic strength and catalytic mineral phases. Confinement of the organic pyrolysate to the bulk sediment accelerated the rates of the biomarker epimerization reactions, suggesting that these reactions are influenced strongly by the association of the inorganic matrix, and that the relative rates of some ionic and radical reactions can be influenced by the water/rock ratio during the pyrolysis experiments.

Application of environmental groundwater tracers at the Sulphur Bank Mercury Mine, California, USA

USGS Publications Warehouse

Engle, M.A.; Goff, F.; Jewett, D.G.; Reller, G.J.; Bauman, J.B.

2008-01-01

Boron, chloride, sulfate, ??D, ??18O, and 3H concentrations in surface water and groundwater samples from the Sulphur Bank Mercury Mine (SBMM), California, USA were used to examine geochemical processes and provide constraints on evaporation and groundwater flow. SBMM is an abandoned sulfur and mercury mine with an underlying hydrothermal system, adjacent to Clear Lake, California. Results for non-3H tracers (i.e., boron, chloride, sulfate, ??D, and ??18O) identify contributions from six water types at SBMM. Processes including evaporation, mixing, hydrothermal water input and possible isotopic exchange with hydrothermal gases are also discerned. Tritium data indicate that hydrothermal waters and other deep groundwaters are likely pre-bomb (before ???1952) in age while most other waters were recharged after ???1990. A boron-based steady-state reservoir model of the Herman Impoundment pit lake indicates that 71-79% of its input is from meteoric water with the remainder from hydrothermal contributions. Results for groundwater samples from six shallow wells over a 6-month period for ??D and ??18O suggests that water from Herman Impoundment is diluted another 3% to more than 40% by infiltrating meteoric water, as it leaves the site. Results for this investigation show that environmental tracers are an effective tool to understand the SBMM hydrogeologic regime. ?? Springer-Verlag 2007.

Mixed biogenic and hydrothermal quartz in Permian lacustrine shale of Santanghu Basin, NW China: implications for penecontemporaneous transformation of silica minerals

NASA Astrophysics Data System (ADS)

Jiao, Xin; Liu, Yiqun; Yang, Wan; Zhou, Dingwu; Wang, Shuangshuang; Jin, Mengqi; Sun, Bin; Fan, Tingting

2018-01-01

The cycling of various isomorphs of authigenic silica minerals is a complex and long-term process. A special type of composite quartz (Qc) grains in tuffaceous shale of Permian Lucaogou Formation in the sediment-starved volcanically and hydrothermally active intracontinental lacustrine Santanghu rift basin (NW China) is studied in detail to demonstrate such processes. Samples from one well in the central basin were subject to petrographic, elemental chemical, and fluid inclusion analyses. About 200 Qc-bearing laminae are 0.1-2 mm and mainly 1 mm thick and intercalated within tuffaceous shale laminae. The Qc grains occur as framework grains and are dispersed in igneous feldspar-dominated matrix, suggesting episodic accumulation. The Qc grains are bedding-parallel, uniform in size (100 s µm), elongate, and radial in crystal pattern, suggesting a biogenic origin. Qc grains are composed of a core of anhedral microcrystalline quartz and an outer part of subhedral mega-quartz grains, whose edges are composed of small euhedral quartz crystals, indicating multiple episodic processes of recrystallization and overgrowth. Abundance of Al and Ti in quartz crystals and estimated temperature from fluid inclusions in Qc grains indicate that processes are related to hydrothermal fluids. Finally, the Qc grains are interpreted as original silica precipitation in microorganism (algae?) cysts, which were reworked by bottom currents and altered by hydrothermal fluids to recrystalize and overgrow during penecontemporaneous shallow burial. It is postulated that episodic volcanic and hydrothermal activities had changed lake water chemistry, temperature, and nutrient supply, resulting in variations in microorganic productivities and silica cycling. The transformation of authigenic silica from amorphous to well crystallized had occurred in a short time span during shallow burial.

Inactivation of Escherichia coli Endotoxin by Soft Hydrothermal Processing▿

PubMed Central

Miyamoto, Toru; Okano, Shinya; Kasai, Noriyuki

2009-01-01

Bacterial endotoxins, also known as lipopolysaccharides, are a fever-producing by-product of gram-negative bacteria commonly known as pyrogens. It is essential to remove endotoxins from parenteral preparations since they have multiple injurious biological activities. Because of their strong heat resistance (e.g., requiring dry-heat sterilization at 250°C for 30 min) and the formation of various supramolecular aggregates, depyrogenation is more difficult than sterilization. We report here that soft hydrothermal processing, which has many advantages in safety and cost efficiency, is sufficient to assure complete depyrogenation by the inactivation of endotoxins. The endotoxin concentration in a sample was measured by using a chromogenic limulus method with an endotoxin-specific limulus reagent. The endotoxin concentration was calculated from a standard curve obtained using a serial dilution of a standard solution. We show that endotoxins were completely inactivated by soft hydrothermal processing at 130°C for 60 min or at 140°C for 30 min in the presence of a high steam saturation ratio or with a flow system. Moreover, it is easy to remove endotoxins from water by soft hydrothermal processing similarly at 130°C for 60 min or at 140°C for 30 min, without any requirement for ultrafiltration, nonselective adsorption with a hydrophobic adsorbent, or an anion exchanger. These findings indicate that soft hydrothermal processing, applied in the presence of a high steam saturation ratio or with a flow system, can inactivate endotoxins and may be useful for the depyrogenation of parenterals, including end products and medical devices that cannot be exposed to the high temperatures of dry heat treatments. PMID:19502435

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

DOEpatents

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.

Hydrothermal activity in the Lau back-arc basin: Sulfides and water chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fouquet, Y.; Charlou, J.L.; Donval, J.P.

1991-04-01

The submersible Nautile completed 22 dives during the Nautilau cruise (R/V Nadir, April 17-May 10, 1989) for a detailed investigation of the southern Lau basin near Tonga. The objective of the scientific team from France, Germany, and Tonga was to understand the process of sea-floor ore formation associated with hydrothermal circulation along the Valu Fa back-arc ridge behind the Tonga-Kermadec trench. The four diving areas, between lat21{degree}25'S and 22{degree}40'S in water{approximately}2000 m deep, were selected on the basis of results from cruises of the R/V Jean Charcot and R/V Sonne. The Nadir cruise provided proof of hydrothermal activity-in all formore » areas, over more than 100 km-as indicated by the widespread occurence of hydrothermal deposits and by heat flow, conductivity, and temperature measurements near the sea bottom. The most spectacular findings were high-temperature white and black smokers and associated fauna and ore deposits. Hydrothermal water chemistry and sulfide composition data presented here indicate that this hydrothermal field is very different from the hydrothermal fields in oceanic ridges. This difference is seen in water chemistry of the hydrothermal fluid (pH=2 and high metal content) and the chemical composition of sulfides (enrichment in Ba, As, and Pb).« less

Along-axis hydrothermal flow at the axis of slow spreading Mid-Ocean Ridges: Insights from numerical models of the Lucky Strike vent field (MAR)

NASA Astrophysics Data System (ADS)

Fontaine, Fabrice J.; Cannat, Mathilde; Escartin, Javier; Crawford, Wayne C.

2014-07-01

processes and efficiency of hydrothermal heat extraction along the axis of mid-ocean ridges are controlled by lithospheric thermal and permeability structures. Hydrothermal circulation models based on the structure of fast and intermediate spreading ridges predict that hydrothermal cell organization and vent site distribution are primarily controlled by the thermodynamics of high-temperature mid-ocean ridge hydrothermal fluids. Using recent constraints on shallow structure at the slow spreading Lucky Strike segment along the Mid-Atlantic Ridge, we present a physical model of hydrothermal cooling that incorporates the specificities of a magma-rich slow spreading environment. Using three-dimensional numerical models, we show that, in contrast to the aforementioned models, the subsurface flow at Lucky Strike is primarily controlled by across-axis permeability variations. Models with across-axis permeability gradients produce along-axis oriented hydrothermal cells and an alternating pattern of heat extraction highs and lows that match the distribution of microseismic clusters recorded at the Lucky Strike axial volcano. The flow is also influenced by temperature gradients at the base of the permeable hydrothermal domain. Although our models are based on the structure and seismicity of the Lucky Strike segment, across-axis permeability gradients are also likely to occur at faster spreading ridges and these results may also have important implications for the cooling of young crust at fast and intermediate spreading centers.

[Diversity of culturable sulfur-oxidizing bacteria in deep-sea hydrothermal vent environments of the South Atlantic].

PubMed

Xu, Hongxiu; Jiang, Lijing; Li, Shaoneng; Zhong, Tianhua; Lai, Qiliang; Shao, Zongze

2016-01-04

To investigate the diversity of culturable sulfur-oxidizing bacteria in hydrothermal vent environments of the South Atlantic, and analyze their characteristics of sulfur oxidation. We enriched and isolated sulfur-oxidizing bacteria from hydrothermal vent samples collected from the South Atlantic. The microbial diversity in enrichment cultures was analyzed using the Denatural Gradient Gel Electrophoresis method. Sulfur-oxidizing characteristics of the isolates was further studied by using ion chromatography. A total of 48 isolates were obtained from the deep-sea hydrothermal vent samples, which belonged to 23 genera and mainly grouped into alpha-Proteobacteria (58.3%), Actinobacteria (22.9%) and gama-Proteobacteria (18.8%). Among them, the genus Thalassospira, Martelella and Microbacterium were dominant. About 60% of the isolates exibited sulfur-oxidizing ability and strain L6M1-5 had a higher sulfur oxidation rate by comparison analysis. The diversity of sulfur-oxidizing bacteria in hydrothermal environments of the South Atlantic was reported for the first time based on culture-dependent methods. The result will help understand the biogechemical process of sulfur compounds in the deep-sea hydrothermal environments.

Production of reducing sugar from Enteromorpha intestinalis by hydrothermal and enzymatic hydrolysis.

PubMed

Kim, Dong-Hyun; Lee, Sang-Bum; Jeong, Gwi-Taek

2014-06-01

In this work, to evaluate the efficacy of marine macro-algae Enteromorpha intestinalis as a potential bioenergy resource, the effects of reaction conditions (solid-to-liquid ratio, reaction temperature, and reaction time) on sugars produced by a combined process of hydrothermal and enzymatic hydrolysis were investigated. As a result of the hydrothermal hydrolysis, a 7.3g/L (8% yield) total reducing sugar was obtained under conditions including solid-to-liquid ratio of 1:10, reaction temperature of 170°C, and reaction time of 60min. By subsequent (post-hydrothermal) enzymatic hydrolysis of samples treated at 170°C for 30min, a 20.1g/L (22% yield) was achieved. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hydrothermal Synthesis of Nanostructured Vanadium Oxides

PubMed Central

Livage, Jacques

2010-01-01

A wide range of vanadium oxides have been obtained via the hydrothermal treatment of aqueous V(V) solutions. They exhibit a large variety of nanostructures ranging from molecular clusters to 1D and 2D layered compounds. Nanotubes are obtained via a self-rolling process while amazing morphologies such as nano-spheres, nano-flowers and even nano-urchins are formed via the self-assembling of nano-particles. This paper provides some correlation between the molecular structure of precursors in the solution and the nanostructure of the solid phases obtained by hydrothermal treatment. PMID:28883325

An Overview of Thermal Measurements (IR) at the Summit of Piton de la Fournaise Active Volcano and Inferences on the Structure and Dynamics of its Hydrothermal System

NASA Astrophysics Data System (ADS)

Fontaine, F.; Peltier, A.; Kowalski, P.; Di Muro, A.; Villeneuve, N.; Ferrazzini, V.; Staudacher, T.

2017-12-01

Piton de la Fournaise, located on La Réunion Island in the South East Indian Ocean, is one of the most active basaltic volcanoes (hotspot) of the world with a mean eruption frequency <6 months over the last 20 years. The central dome of the shield is thought to host an active hydrothermal system evidenced by self-potential techniques early in the 90's and mining heat from a magmatic source located about 2-2.5 km below the summit. Surface manifestations of this activity such as fumeroles or hot grounds have however never been observed before 2007 when deep magma withdrawal from the magmatic horizon during the "eruption of the century" (>100×106 m3) on the island, led to the formation of a 400-m-deep, 1000-m-large, funnel-shaped summit caldera. Since then, the floor and inner flanks of this summit depression hosting hot grounds and active fumaroles, are monitored using an infra-red camera device permanently installed on the caldera rim.This thermal dataset constitutes the first opportunity to understand the structure and dynamics of the hydrothermal system and its ability to relay deep-seated heat and mass perturbations. We present in this communication an overview of this thermal datasets focusing on ground/fumaroles temperature evolution during volcanic crisis and rest periods and analyzing correlations with the other permanently acquired data such as the temporal evolution of gas geochemistry (CO2, SO2, H2S), ground deformation and micro-seismic activity. We finally propose a conceptual model of fluid flow architecture within the edifice which paves the way for future quantitative models of hydrothermal heat and mass transfers.

Industrial symbiosis: corn ethanol fermentation, hydrothermal carbonization, and anaerobic digestion.

PubMed

Wood, Brandon M; Jader, Lindsey R; Schendel, Frederick J; Hahn, Nicholas J; Valentas, Kenneth J; McNamara, Patrick J; Novak, Paige M; Heilmann, Steven M

2013-10-01

The production of dry-grind corn ethanol results in the generation of intermediate products, thin and whole stillage, which require energy-intensive downstream processing for conversion into commercial animal feed products. Hydrothermal carbonization of thin and whole stillage coupled with anaerobic digestion was investigated as alternative processing methods that could benefit the industry. By substantially eliminating evaporation of water, reductions in downstream energy consumption from 65% to 73% were achieved while generating hydrochar, fatty acids, treated process water, and biogas co-products providing new opportunities for the industry. Processing whole stillage in this manner produced the four co-products, eliminated centrifugation and evaporation, and substantially reduced drying. With thin stillage, all four co-products were again produced, as well as a high quality animal feed. Anaerobic digestion of the aqueous product stream from the hydrothermal carbonization of thin stillage reduced chemical oxygen demand (COD) by more than 90% and converted 83% of the initial COD to methane. Internal use of this biogas could entirely fuel the HTC process and reduce overall natural gas usage. Copyright © 2013 Wiley Periodicals, Inc.

Origin of magnetic highs at ultramafic hosted hydrothermal systems: Insights from the Yokoniwa site of Central Indian Ridge

NASA Astrophysics Data System (ADS)

Fujii, Masakazu; Okino, Kyoko; Sato, Taichi; Sato, Hiroshi; Nakamura, Kentaro

2016-05-01

High-resolution vector magnetic measurements were performed on an inactive ultramafic-hosted hydrothermal vent field, called Yokoniwa Hydrothermal Field (YHF), using a deep-sea manned submersible Shinkai6500 and an autonomous underwater vehicle r2D4. The YHF has developed at a non-transform offset massif of the Central Indian Ridge. Dead chimneys were widely observed around the YHF along with a very weak venting of low-temperature fluids so that hydrothermal activity of the YHF was almost finished. The distribution of crustal magnetization from the magnetic anomaly revealed that the YHF is associated with enhanced magnetization, as seen at the ultramafic-hosted Rainbow and Ashadze-1 hydrothermal sites of the Mid-Atlantic Ridge. The results of rock magnetic analysis on seafloor rock samples (including basalt, dolerite, gabbro, serpentinized peridotite, and hydrothermal sulfide) showed that only highly serpentinized peridotite carries high magnetic susceptibility and that the natural remanent magnetization intensity can explain the high magnetization of Yokoniwa. These observations reflect abundant and strongly magnetized magnetite grains within the highly serpentinized peridotite. Comparisons with the Rainbow and Ashadze-1 suggest that in ultramafic-hosted hydrothermal systems, strongly magnetized magnetite and pyrrhotite form during the progression of hydrothermal alteration of peridotite. After the completion of serpentinization and production of hydrogen, pyrrhotites convert into pyrite or nonmagnetic iron sulfides, which considerably reduces their levels of magnetization. Our results revealed origins of the magnetic high and the development of subsurface chemical processes in ultramafic-hosted hydrothermal systems. Furthermore, the results highlight the use of near-seafloor magnetic field measurements as a powerful tool for detecting and characterizing seafloor hydrothermal systems.

Formation of hydrothermal biochar and char stability in soils

NASA Astrophysics Data System (ADS)

Baumert, Julia; Gleixner, Gerd

2010-05-01

The use of charcoal as an artificial soil additive is suggested to beneficially modify degraded soil, reduce greenhouse gas emission and improve crop yields. So far research has been mainly done using pyrolysis chars which are produced by dry pyrolysis of biomass. Here we used hydrothermal carbonisation (HTC). In this process wet biomass is converted to char at moderate temperatures (~200°C). Due to the exothermal carbonisation reaction this process is almost energy neutral, i.e. the energy needed to start the carbonisation equals the energy released during carbonisation. Different process parameters have been used to modify the properties of the produced chars. We examined the chemical and morphological properties of hydrothermally synthesized biochar. Cellulose, yeast and sucrose were used as model substances for a range of parent material types like organic and garden waste as well as residues from biogas production. By modifying the process conditions of hydrothermal carbonisation concerning temperature (180°C to 220°C) and duration (6 hours to 24 hours) we produced a variety of different biochars. Our findings suggest that the elemental composition and the thermal stability of resulting chars depend on the feedstock and production conditions. Functional group chemistry determined by NMR shows that the aromaticity of the product increases as a function of temperature whereas the amount of O-alkylic compounds declines, concurrently. Our results show that the properties of the biochar can be manipulated by the modification of process conditions. This opens the opportunity to adjust the charcoal to a given soil type.

Agro-industrial waste to solid biofuel through hydrothermal carbonization.

PubMed

Basso, Daniele; Patuzzi, Francesco; Castello, Daniele; Baratieri, Marco; Rada, Elena Cristina; Weiss-Hortala, Elsa; Fiori, Luca

2016-01-01

In this paper, the use of grape marc for energy purposes was investigated. Grape marc is a residual lignocellulosic by-product from the winery industry, which is present in every world region where vine-making is addressed. Among the others, hydrothermal carbonization was chosen as a promising alternative thermochemical process, suitable for the treatment of this high moisture substrate. Through a 50 mL experimental apparatus, hydrothermal carbonization tests were performed at several temperatures (namely: 180, 220 and 250 °C) and residence times (1, 3, 8 h). Analyses on both the solid and the gaseous phases obtained downstream of the process were performed. In particular, solid and gas yields versus the process operational conditions were studied and the obtained hydrochar was evaluated in terms of calorific value, elemental analysis, and thermal stability. Data testify that hydrochar form grape marc presents interesting values of HHV (in the range 19.8-24.1 MJ/kg) and physical-chemical characteristics which make hydrochar exploitable as a solid biofuel. In the meanwhile, the amount of gases produced is very small, if compared to other thermochemical processes. This represents an interesting result when considering environmental issues. Statistical analysis of data allows to affirm that, in the chosen range of operational conditions, the process is influenced more by temperature than residence time. These preliminary results support the option of upgrading grape marc toward its energetic valorisation through hydrothermal carbonization. Copyright © 2015 Elsevier Ltd. All rights reserved.

Dark fermentation process as pretreatment for a sustainable denaturation of asbestos containing wastes.

PubMed

Spasiano, Danilo

2018-05-05

A cement asbestos compound (CAC) sample was detoxified by a treatment train based on a dark fermentation (DF) process followed by a hydrothermal phase, which led to the complete degradation of the chrysotile fibers. During the biological pretreatment, the glucose was converted in biogas rich in H 2 and volatile fatty acids (VFA). The latter caused the dissolution of all the Ca-based compounds and the solubilisation of 50% brucite-like layers of chrysotile fibers contained in the CAC suspended in the bioreactor (5 g/L). XRD analysis of the solids contained in the effluents of the DF process highlighted the disappearance of the chrysotile fiber peaks. However, a complete destruction of all the asbestos fibers is hard to prove and a hydrothermal treatment was carried out to dissolve the "brucite" layers still present in solution. Due to the presence of the VFA produced during the DF, a complete destruction of chrysotile fibers was achieved by a 24 h hydrothermal process performed with a [H 2 SO 4 ]/[CAC] ratio 50% lower than that adopted in a previous finding. Consequently, the DF pre-treatment can contribute to lower the H 2 SO 4 and the energy consumption of a CAC hydrothermal treatment, due to the production of VFA and H 2 . Copyright © 2018 Elsevier B.V. All rights reserved.

Hydrothermal synthesis of histidine-functionalized single-crystalline gold nanoparticles and their pH-dependent UV absorption characteristic.

PubMed

Liu, Zhiguo; Zu, Yuangang; Fu, Yujie; Meng, Ronghua; Guo, Songling; Xing, Zhimin; Tan, Shengnan

2010-03-01

L-Histidine capped single-crystalline gold nanoparticles have been synthesized by a hydrothermal process under a basic condition at temperature between 65 and 150 degrees C. The produced gold nanoparticles were spherical with average diameter of 11.5+/-2.9nm. The synthesized gold colloidal solution was very stable and can be stored at room temperature for more than 6 months. The color of the colloidal solution can change from wine red to mauve, purple and blue during the acidifying process. This color changing phenomenon is attributed to the aggregation of gold nanoparticles resulted from hydrogen bond formation between the histidines adsorbed on the gold nanoparticles surfaces. This hydrothermal synthetic method is expected to be used for synthesizing some other amino acid functionalized gold nanomaterials.

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 zones of active extension) common to all spreading centers, regional tectonic setting determined by stage (early, advanced), and rate (slow, intermediate-to-fast) of opening of an ocean basin about a spreading center, and local tectonic sub-setting that incorporates anomalous structural and thermal conditions conducive to mineral concentration (thermal gradient, permeability, system geometry, leaky versus tight hydrothermal systems). Temporal frames of reference comprise the relation between mineral concentration and timing of regional plutonic, volcanic and tectonic cycles and of episodic local physical and chemical events (transient stress, fluctuating heat transfer, intrusion-extrusion, fracturing, sealing, etc.). Types of hydrothermal deposits are not uniquely associated with specific tectonic settings and subsettings. Similar types of hydrothermal deposits may occur in different tectonic settings as a consequence of convergence of physical and chemical processes of concentration. Local tectonic sub-settings with conditions conducive to hydrothermal mineralization at slow-spreading centers (half rate ≤ 2cm y -1; length c. 28,000 km), characterized by an estimated average convective heat transfer of 15.1·10 8 cal. cm -2, deep-level ( > 3 km), relative narrow (< 5 km wide at base) magma chambers, and high topographic relief (1-5 km) are: (1) basins along linear sections of the axial zone of volcanic extrusion near transform faults at an early stage of opening, represented by a large stratiform sulfide deposit (estimated 32.5·10 6 metric tons) of the Atlantis II Deep of the Red Sea; (2) the wall along linear sections of the rift valley in the marginal zone of active extension at an advanced stage of opening, represented by encrustations and layered deposits of manganese and iron oxides, hydroxides and silicates inferred to be underlain by stockwork sulfides at the TAG Hydrothermal Field at latitude 26°C on the Mid-Atlantic Ridge; (3) transform faults, especially those with large ridge-ridge offset ( > 30 km), at an advanced stage of opening, represented by stockwork sulfides exposed in the walls of equatorial fracture zones of the Atlantic Ocean and Indian Ocean; (4) the axial zone of volcanic extrusion at an advanced stage of opening. Local tectonic sub-settings with conditions conducive to hydrothermal mineralization at intermediate- to fast-spreading centers (half rate > 2cm y -1; length c. 22,000 km) characterized by an estimated average convective heat transfer of 11.5·10 8 cal. cm -2, relatively wide (up to 20 km at base), shallow-level (c. 1-3 km) magma chambers, and low topographic relief (< 1 km), are: (1) basins along linear sections of the axial zone of volcanic extrusion at an early stage of opening, represented by massive sulfide deposits of the Guaymas Basin of the Gulf of California; (2) the axial zone of volcanic extrusion at an advanced stage of opening, represented by individually small (c. 1·10 3 metric tons), massive sulfide mounds surmounted by chimneys of the East Pacific Rise at latitude 21°N; (3) the marginal zone of active extension at an advanced stage of opening represented by a large, massive sulfide deposit (preliminary tentative estimate c.10·10 6 metric tons) at a double-rifted section of the Galapagos Spreading Center; (4) transform faults, especially those with large ridge-ridge offset ( > 50 km) represented by manganese encrustations in a transform fault at the Galapagos Spreading Center; (5) volcanic seamounts related to persistent hot spots at spreading centers, represented by oxide and sulfide deposits on seamounts off the axis of the East Pacific Rise; (6) portions of spreading centers with anomalous configurations such as multiple, bent or extended rifts, represented by massive sulfide deposits at a double-rifted section of the Galapagos Spreading Center, suggesting the operation of a thermal-structural feedback mechanism indicative of the presence of hydrothermal mineralization; (7) discrete spreading centers in back-arc basins represented by hydrothermal deposits at sites in marginal seas of the western Pacific. Ore-forming processes appear to be least efficient in the axial zone of volcanic extrusion of oceanic ridges at an advanced stage of opening irrespective of spreading rate, where tight hydrothermal systems dissipate a major portion of contained metals by precipitation and dispersion in particulate form from "black smokers" that discharge into the water column. Ore-forming processes appear to be most efficient at sites in basins at linear sections of the axial zone of volcanic extrusion near transform faults during an early stage of opening, and at marginal zones of active extension along linear sections of a spreading center during an advanced stage of opening, irrespective of spreading rate, where both tight and leaky hydrothermal systems may conserve their contained metals to concentrate large sulfide deposits. Resemblances in mineralization between stockwork sulfides at seafloor spreading centers and porphyry copper-type deposits in volcanogenic rocks on land suggest the possibility for the occurrence of large tonnage, low-grade porphyry copper-like deposits concentrated by leaky hydrothermal systems at spreading centers. Systematic application of composite exploration procedures is leading to the discovery of numerous additional deposits. It is inferred from the limited data base available that the occurrence of hydrothermal mineral deposits is more frequent at intermediate-to-fast-than at slow-spreading centers, but the potential for the accumulation of large hydrothermal mineral deposits is greater at slow-spreading centers. Current knowledge of the distribution of hydrothermal mineral deposits at seafloor spreading centers is limited to about 55 sites at this early stage of exploration. Estimates of the distribution of either fields of hydrothermal mineral deposits or high-intensity ore-forming hydrothermal systems at seafloor spreading centers, deduced from various considerations, range from one such occurrence between 15 and 265 km along slow-spreading centers, and 1 and 100 km along intermediate- to fast-spreading centers. However, the distribution of sizable deposits will remain sporadic owing to the special structural and thermal conditions necessary to sustain and to retain high-intensity ore-forming hydrothermal systems.

Comparison of the effects of different heat treatment processes on rheological properties of cake and bread wheat flours.

PubMed

Bucsella, Blanka; Takács, Ágnes; Vizer, Viktoria; Schwendener, Urs; Tömösközi, Sándor

2016-01-01

Dry and hydrothermal heat treatments are efficient for modifying the technological-functional and shelf-life properties of wheat milling products. Dry heat treatment process is commonly used to enhance the volume of cakes. Hydrothermal heat treatment makes wheat flours suitable as thickener agents. In this study, cake and bread wheat flours that differed in baking properties were exposed to dry (100 °C, 12 min) and hydrothermal (95 °C, 5 min, 5-20 l/h water) heat treatments. Rheological differences caused by the treatments were investigated in a diluted slurry and in a dough matrix. Dry heat treatment resulted in enhanced dough stability. This effect was significantly higher in the cake flour than the bread flour. Altered viscosity properties of the bread flour in the slurry matrix were also observed. The characteristics of hydrothermally treated samples showed matrix dependency: their viscosity increases in the slurry and decreases in the dough matrix. These results can support us to produce flour products with specific techno-functional properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

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.

Iron-tolerant Cyanobacteria as a Tool to Study Terrestrial and Extraterrestrial Iron Deposition

NASA Technical Reports Server (NTRS)

Brown, I. I.; Mummey, D.; Cooksey, K. E.; McKay, D. S.

2005-01-01

We are investigating biological mechanisms of terrestrial iron deposition as analogs for Martian hematite recently confirmed by. Possible terrestrial analogs include iron oxide hydrothermal deposits, rock varnish, iron-rich laterites, ferricrete soils, moki balls, and banded iron formations (BIFs). With the discovery of recent volcanic activity in the summit craters of five Martian volcanoes, renewed interest in the iron dynamics of terrestrial hydrothermal environments and associated microorganisms is warranted. In this study we describe a new genus and species of CB exhibiting elevated dissolved iron tolerance and the ability to precipitate hematite on the surface of their exopolymeric sheathes.

TEMPEST: A three-dimensional time-dependent computer program for hydrothermal analysis: Volume 1, Numerical methods and input instructions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trent, D.S.; Eyler, L.L.; Budden, M.J.

This document describes the numerical methods, current capabilities, and the use of the TEMPEST (Version L, MOD 2) computer program. TEMPEST is a transient, three-dimensional, hydrothermal computer program that is designed to analyze a broad range of coupled fluid dynamic and heat transfer systems of particular interest to the Fast Breeder Reactor thermal-hydraulic design community. The full three-dimensional, time-dependent equations of motion, continuity, and heat transport are solved for either laminar or turbulent fluid flow, including heat diffusion and generation in both solid and liquid materials. 10 refs., 22 figs., 2 tabs.

Behaviour of elements in soils developed from nephelinites at Mount Etinde (Cameroon): Impact of hydrothermal versus weathering processes

NASA Astrophysics Data System (ADS)

Etame, J.; Gerard, M.; Bilong, P.; Suh, C. E.

2009-05-01

The progressive weathering of 0.65 Ma nephelinites from Mount Etinde (South Western Cameroon) in a humid tropical setting has resulted in the formation of a 150 cm thick weathering crust. The soil profiles consist of three horizons: Ah/Bw/C. A major differentiation of the chemical and mineralogical parameters is related to the complexity of the saprolites, some of which were hydrothermally altered. Bulk geochemical and microgeochemical analyses were performed on selected minerals from the different horizons of two reference profiles, of which one (E 4) was developed from unaltered nephelinite (nephelinite U) while the other (BO 1) formed from hydrothermally altered nephelinite (nephelinite H). The results show that the primary minerals (clinopyroxene, nepheline, leucite, haüyne, titanomagnetite, perovskite, apatite and sphene) experienced differential weathering rates with primary minerals rich in rare earth elements (titanomagnetite, perovskite, apatite and sphene) surviving in the saprolite and the Bw horizons. The weathering of the primary minerals is reflected in the leaching of alkaline and alkaline-earth elements, except for Ba and Rb in the hydrothermalised nephelinite soil. The order of mobility is influenced by hydrothermal processes: Na > K > Rb > Ca > Cs > Sr in nephelinite U soil , Na > K > Sr > Ca > Mg in nephelinite H soil; Rb/Sr and Sr/Mg can be used as indicators of the kinetic of the weathering on nephelinite U and on nephelinite H. Barium enrichment is related to variable concentrations in the nephelinites, to the formation of crandallites and the leaching of surface horizons. The content of metallic elements is higher in nephelinite H soil than in the nephelinite U soil. Results show that hydrothermal alteration leads to an enrichment of light (La, Ce, Nd) and intermediate (Sm, Eu, Dy) rare earth elements. The enrichment in Cr and Pb in the surface horizons is discussed in relation to organic matter activity, the dissolution of magnetites, and the impact of hydrothermal processes as well as atmospheric pollution in the case of lead.

Conversion of municipal solid waste to hydrogen

NASA Astrophysics Data System (ADS)

Richardson, J. H.; Rogers, R. S.; Thorsness, C. B.

1995-04-01

LLNL and Texaco are cooperatively developing a physical and chemical treatment method for the conversion of municipal solid waste (MSW) to hydrogen via the steps of hydrothermal pretreatment, gasification and purification. LLNL's focus has been on hydrothermal pretreatment of MSW in order to prepare a slurry of suitable viscosity and heating value to allow efficient and economical gasification and hydrogen production. The project has evolved along 3 parallel paths: laboratory scale experiments, pilot scale processing, and process modeling. Initial laboratory-scale MSW treatment results (e.g., viscosity, slurry solids content) over a range of temperatures and times with newspaper and plastics will be presented. Viscosity measurements have been correlated with results obtained at MRL. A hydrothermal treatment pilot facility has been rented from Texaco and is being reconfigured at LLNL; the status of that facility and plans for initial runs will be described. Several different operational scenarios have been modeled. Steady state processes have been modeled with ASPEN PLUS; consideration of steam injection in a batch mode was handled using continuous process modules. A transient model derived from a general purpose packed bed model is being developed which can examine the aspects of steam heating inside the hydrothermal reactor vessel. These models have been applied to pilot and commercial scale scenarios as a function of MSW input parameters and have been used to outline initial overall economic trends. Part of the modeling, an overview of the MSW gasification process and the modeling of the MSW as a process material, was completed by a DOE SERS (Science and Engineering Research Semester) student. The ultimate programmatic goal is the technical demonstration of the gasification of MSW to hydrogen at the laboratory and pilot scale and the economic analysis of the commercial feasibility of such a process.

Submarine hydrothermal processes, mirroring the geotectonic evolution of the NE Hungarian Jurassic Szarvaskő Unit

NASA Astrophysics Data System (ADS)

Kiss, Gabriella B.; Zagyva, Tamás; Pásztor, Domokos; Zaccarini, Federica

2018-05-01

The Jurassic pillow basalt of the NE Hungarian Szarvaskő Unit is part of an incomplete ophiolitic sequence, formed in a back-arc- or marginal basin of Neotethyan origin. Different, often superimposing hydrothermal processes were studied aiming to characterise them and to discover their relationship with the geotectonic evolution of the region. Closely packed pillow, pillow-fragmented hyaloclastite breccia and transition to peperitic facies of a submarine lava flow were observed. The rocks underwent primary and cooling-related local submarine hydrothermal processes immediately after eruption at ridge setting. Physico-chemical data of this process and volcanic facies analyses revealed distal formation in the submarine lava flow. A superimposing, more extensive fluid circulation system resulted in intense alteration of basalt and in the formation of mostly sulphide-filled cavities. This lower temperature, but larger-scale process was similar to VMS systems and was related to ridge setting. As a peculiarity of the Szarvaskő Unit, locally basalt may be completely altered to a grossular-bearing mineral assemblage formed by rodingitisation s.l. This unique process observed in basalt happened in ridge setting/during spreading, in the absence of known large ultramafic blocks. Epigenetic veins formed also during Alpine regional metamorphism, related to subduction/obduction. The observed hydrothermal minerals represent different steps of the geotectonic evolution of the Szarvaskő Unit, from the ridge setting and spreading till the subduction/obduction. Hence, studying the superimposing alteration mineral assemblages can be a useful tool for reconstructing the tectonic history of an ophiolitic complex. Though the found mineral parageneses are often similar, careful study can help in distinguishing the processes and characterising their P, T, and X conditions.

Can Low Water/Rock Hydrothermal Alteration of Impact Materials Explain the Rock Component of the Martian Soil?

NASA Technical Reports Server (NTRS)

Nelson, M. J.; Newsom, H. E.

2003-01-01

The martian regolith is a globally homogenized product of chemical and aeolian weathering processes. The soil is thought to consist of a rock component, with lesser amounts of mobile elements (Ca, Na, and K) than a presumed protolith, and a salt or mobile element component enriched in sulfur and chlorine. In this study we consider the contributions of hydrothermal processes to the origin of the rock component of the martian soil.

The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

NASA Astrophysics Data System (ADS)

Bemis, Karen G.; Silver, Deborah; Xu, Guangyu; Light, Russ; Jackson, Darrell; Jones, Christopher; Ozer, Sedat; Liu, Li

2015-11-01

Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

Electron microscopy study of microbial mat in the North Fiji basin hydrothermal vent

NASA Astrophysics Data System (ADS)

Park, H.; Kim, J. W.; Lee, J. W.

2017-12-01

Hydrothermal vent systems consisting of hydrothermal vent, hydrothermal sediment and microbial mat are widely spread around the ocean, particularly spreading axis, continental margin and back-arc basin. Scientists have perceived that the hydrothermal systems, which reflect the primeval earth environment, are one of the best places to reveal the origin of life and extensive biogeochemical process of microbe-mineral interaction. In the present study multiline of analytical methods (X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)) were utilized to investigate the mineralogy/chemistry of microbe-mineral interaction in hydrothermal microbial mat. Microbial mat samples were recovered by Canadian scientific submersible ROPOS on South Pacific North Fiji basin KIOST hydrothermal vent expedition 1602. XRD analysis showed that red-colored microbial mat contains Fe-oxides and Fe-oxyhydroxides. Various morphologies of minerals in the red-colored microbial mat observed by SEM are mainly showed sheath shaped, resembled with Leptothrix microbial structure, stalks shaped, similar with Marioprofundus microbial structure and globule shaped microbial structures. They are also detected with DNA analysis. The cross sectional observation of microbial structures encrusted with Fe-oxide and Fe-oxyhydroxide at a nano scale by Transmission Electron Microscopy (TEM) and Focused Ion Beam (FIB) technique was developed to verify the structural/biogeochemical properties in the microbe-mineral interaction. Systematic nano-scale measurements on the biomineralization in the microbial mat leads the understandings of biogeochemical environments around the hydrothermal vent.

Preface

NASA Astrophysics Data System (ADS)

Taran, Yuri; Tassi, Franco; Varekamp, Johan; Inguaggiato, Salvatore; Kalacheva, Elena

2017-10-01

Many volcanoes at any tectonic settings host hydrothermal systems. Volcano-hydrothermal systems (VHS) are result of interaction of the upper part of plumbing systems of active volcanoes with crust, hydrosphere and atmosphere. They are heated by magma, fed by magmatic fluids and meteoric (sea) water, transport and re-distribute magmatic and crustal material. VHS are sensitive to the activity of a host volcano. VHS may have specific features depending on the regional and local tectonic, geologic and geographic settings. The studies reported in this volume help to illustrate the diversity of the approaches and investigations that are being conducting at different volcano-hydrothermal systems over the world and the results of which will be of important value in furthering our understanding of the complex array of the processes accompanying hydrothermal activity of volcanoes. About 60 papers were submitted to a special session of "Volcano-Hydrothermal Systems" at the 2015 fall meeting of the American Geophysical Union. The papers in this special issue of the Journal of Volcanology and Geothermal Research were originally presented at that session.

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. © The Author(s) 2015.

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 intergrowth with REE fluorocarbonates; (4) the CO3-rich hydrothermal fluid corroded type-3, forming Nb-REE-poor zircons (type-3). Niobium and REE was no longer stable in the zircon structure and crystallized as fergusonite around the REE-Nb-leached zircon (type-4); (5) type-5 zircons are formed from more CO3-rich hydrothermal alteration of type-3 zircon. Therefore, type-4 and -5 zircons are often included in ankerite. Type 3-5 zircons at Nechalacho REE deposit were formed by leaching and/or dissolution of type-2 zircon in the presence of F- and/or CO3-rich hydrothermal fluid. The above mineral association indicates that three hydrothermal stages were present and related to HFSE enrichment in the Nechalacho REE deposit: (1) F-rich hydrothermal stage caused the crystallization of REE-Nb-rich zircon (type-2 rim and type-3), with abundant formation of phlogophite and fluorite, (2) F-CO3-rich hydrothermal stage led to the replacement of a part of REE-Nb-F-rich zircon by REE fluorocarbonate and (3) hydrothermal stage rich in CO3 resulted in crystallization of REE-Nb-F-poor zircon and fergusonite, with ankerite. Increases of HFSE contents, REE-Nb-F-poor zircon (type-4 and -5) and fergusonite contents during progress of hydrothermal alteration show that REE and Nb in hydrothermal fluid in the Nechalacho REE deposit were finally concentrated into fergusonite by way of zircon.

European and Middle-East ferroan hydrothermal dolomites: lessons learnt with respect to crustal dynamics, fluid circulations and rock-fluid interactions

NASA Astrophysics Data System (ADS)

Nader, Fadi Henri; Gasparrini, Marta; Bachaud, Pierre

2016-04-01

Classical case studies of hydrothermal dolostones, which are known worldwide to provide excellent reservoirs for ores and hydrocarbons, often illustrate the presence of iron-rich dolomite phases. The world-class hydrothermal dolostones from the Basque-Cantabrian Basin (Northern Spain) exemplify the initiation of high temperature dolomitization (at about 200°C), with significant amount of ferroan dolomite phases (including up to 2% FeO). These dolomites are believed to be responsible for the pervasive replacement of the original limestone rocks - they are followed by non-ferroan dolomite phases. The associated fluids are supposed to have interacted with basement rocks, and travelled from deep-seated sources along major fault pathways. The geochemical traits of such fluids are also typically similar to, and probably associated with, mineralization fluids (e.g. Pb-Zn, MVT). In the Middle East, several observed dolostones show, on the contrary, a later phase of ferroan dolomite cements which occlude the inter-crystalline porosity of earlier non-ferroan matrix dolomites. Dolomitization occurred under increasingly higher temperatures (from 50 to 100°C) during burial. Here, the origin of iron-rich fluids and conditions of precipitation of associated dolomites do not necessarily involve interactions with basement rocks, but rather a relative Fe-enrichment with further reducing settings. Based on previous research projects concerning a variety of dolostones from Europe and the Middle-East, this contribution presents observational, analytical and computational results focused on ferroan dolomites. Recent numerical geochemical modelling emphasized the physico-chemical pre-requisites for crystallizing ferroan rather than non-ferroan dolomites (and vice-versa), allowing better understanding of related diagenetic processes. Besides, important larger-scale information on the crustal fluid circulations are demonstrated to be intimately associated to the parent-fluids sources and the conditions of mineral precipitation. By adopting this approach, ferroan dolomites are no longer considered simply as accessory diagenetic phases. They rather provide significant clues for understanding crustal dynamics and the impacts of evolving rock-fluid interactions on carbonate reservoir properties which are essential for ore and hydrocarbon exploitation, and for underground storage and gas sequestration.

Geochemical evidences of magma dynamics at Campi Flegrei (Italy)

NASA Astrophysics Data System (ADS)

Caliro, S.; Chiodini, G.; Paonita, A.

2014-05-01

Campi Flegrei caldera, within the Neapolitan area of Italy, is potentially one of the most dangerous volcanoes in the world, and during the last decade it has shown clear signs of reactivation, marked by the onset of uplift and changes in the geochemistry of gas emissions. We describe a 30-year-long data set of the CO2-He-Ar-N2 compositions of fumarolic emissions from La Solfatara crater, which is located in the center of the caldera. The data display continuous decreases in both the N2/He and N2/CO2 ratios since 1985, paralleled by an increase in He/CO2. These variations cannot be explained by either processes of boiling/condensation in the local hydrothermal system or with changes in the mixing proportions between a magmatic vapor and hydrothermal fluids. We applied the magma degassing model of Nuccio and Paonita (2001, Earth Planet. Sci. Lett. 193, 467-481) using the most recent inert-gas solubilities in order to interpret these peculiar features in accordance with petrologic constraints derived from the ranges of the melt compositions and reservoir pressures at Campi Flegrei. The model simulations for mafic melts (trachybasalt and shoshonite) show a remarkably good agreement with the measured data. Both decompressive degassing of an ascending magma and mixing between magmatic fluids exsolved at various levels along the ascent path can explain the long-term geochemical changes. Recalling that (i) a sill-like reservoir of gases at a depth of 3-4 km seems to be the main source of ground inflation and (ii) there is petrologic and geophysical evidence for a reservoir of magma at about 8 km below Campi Flegrei, we suggest that the most-intense episodes of inflation occur when the gas supply to the sill-like reservoir comes from the 8 km-deep magma, although fluids exsolved by magma bodies at shallower depths also contribute to the gas budget. Our work highlights that, in caldera systems where the presence of hydrothermal aquifers commonly masks the magmatic signature of reactive volatiles, inert gases are the preferred species to use when seeking information on the melt composition, dynamics, and structure of the plumbing systems.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Köferstein, Roberto, E-mail: roberto.koeferstein@chemie.uni-halle.de; 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 andmore » 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 magnetic behaviour.« less

Variability of Fe isotope compositions of hydrothermal sulfides and oxidation products at mid-ocean ridges

NASA Astrophysics Data System (ADS)

Li, Xiaohu; Wang, Jianqiang; Chu, Fengyou; Wang, Hao; Li, Zhenggang; Yu, Xing; Bi, Dongwei; He, Yongsheng

2018-04-01

Significant Fe isotopic fractionation occurs during the precipitation and oxidative weathering of modern seafloor hydrothermal sulfides, which has an important impact on the cycling of Fe isotopes in the ocean. This study reports the Fe-isotope compositions of whole-rock sulfides and single-mineral pyrite collected from hydrothermal fields at the South Mid-Atlantic Ridge (SMAR) and the East Pacific Rise (EPR) and discusses the impacts of precipitation and late-stage oxidative weathering of sulfide minerals on Fe isotopic fractionation. The results show large variation in the Fe-isotope compositions of the sulfides from the different hydrothermal fields on the mid-oceanic ridges, indicating that relatively significant isotope fractionation occurs during the sulfide precipitation and oxidative weathering processes. The Fe-isotope compositions of the sulfides from the study area at the SMAR vary across a relatively small range, with an average value of 0.01‰. This Fe-isotope composition is similar to the Fe-isotope composition of mid-oceanic ridge basalt, which suggests that Fe was mainly leached from basalt. In contrast, the Fe-isotope composition of the sulfides from the study area at the EPR are significantly enriched in light Fe isotopes (average value - 1.63‰), mainly due to the kinetic fractionation during the rapid precipitation process of hydrothermal sulfide. In addition, the pyrite from different hydrothermal fields is enriched in light Fe isotopes, which is consistent with the phenomenon in which light Fe isotopes are preferentially enriched during the precipitation of pyrite. The red oxides have the heaviest Fe-isotope compositions (up to 0.80‰), indicating that heavy Fe isotopes are preferentially enriched in the oxidation product during the late-stage oxidation process. The data obtained from this study and previous studies show a significant difference between the Fe-isotope compositions of the sulfides from the SMAR and EPR. The relatively heavy Fe isotopes compositions of the sulfides from the SMAR may suggest the equilibrium fractionation process under high temperature conditions. The red Fe oxides are enriched in heavy Fe isotopes, indicating that the oxidative weathering processes result in the occurrence of significant Fe-isotope fractionation and the preferential enrichment of heavy Fe isotopes in the oxidation product.

Stable Carbon Isotopic Signatures of Abiotic Organics from Hydrothermal Synthesis Experiments

NASA Technical Reports Server (NTRS)

Stern, Jennifer C.; Summers, David P.; Kubo, Mike; Yassar, Saima

2006-01-01

Stable carbon isotopes can be powerful biogeochemical markers in the study of life's origins. Biogenic carbon fixation produces organics that are depleted in C-13 by about -20 to -30%0. Less attention has been paid to the isotopic signatures of abiotic processes. The possibility of abiotic processes producing organics with morphologies and isotopic signatures in the biogenic range has been at the center of recent debate over the Earth's earliest microfossils. The abiotic synthesis of organic compounds in hydrothermal environments is one possible source of endogenous organic matter to the prebiotic earth. Simulated hydrothermal settings have been shown to synthesize, among other things, single chain amphiphiles and simple lipids from a mix of CO, CO2, and H2. A key characteristic of these amphiphilic molecules is the ability to self-assemble in aqueous phases into more organized structures called vesicles, which form a selectively permeable boundary and serve the function of containing and concentrating other organic molecules. The ability to form cell like structures also makes these compounds more likely to be mistaken for biogenic. Hydrothermal simulation experiments were conducted from oxalic or formic acid in water at 175 C for 72 hr. The molecular and isotopic composition of the products of these reactions were determined and compared to biogenic fractionations . Preliminary results indicate isotopic fractionation during abiotic hydrocarbon synthesis in hydrothermal environments is on par with biological carbon fixation.

Gas-sensing enhancement methods for hydrothermal synthesized SnO2-based sensors

NASA Astrophysics Data System (ADS)

Zhao, Yalei; Zhang, Wenlong; Yang, Bin; Liu, Jingquan; Chen, Xiang; Wang, Xiaolin; Yang, Chunsheng

2017-11-01

Gas sensing for hydrothermal synthesized SnO2-based gas sensors can be enhanced in three ways: structural improvement, composition optimization, and processing improvement. There have been zero-dimensional, one-dimensional, and three-dimensional structures reported in the literature. Controllable synthesis of different structures has been deployed to increase specific surface area. Change of composition would intensively tailor the SnO2 structure, which affected the gas-sensing performance. Furthermore, doping and compounding methods have been adopted to promote gas-sensing performance by adjusting surface conditions of SnO2 crystals and constructing heterojunctions. As for processing area, it is very important to find the optimal reaction time and temperature. In this paper, a gas-solid reaction rate constant was proposed to evaluate gas-sensing properties and find an excellent hydrothermal synthesized SnO2-based gas sensor.

A series of spinel phase cathode materials prepared by a simple hydrothermal process for rechargeable lithium batteries

NASA Astrophysics Data System (ADS)

Liang, Yan-Yu; Bao, Shu-Juan; Li, Hu-Lin

2006-07-01

A series of spinel-structured materials have been prepared by a simple hydrothermal procedure in an aqueous medium. The new synthetic method is time and energy saving i.e., no further thermal treatment and extended grinding. The main experimental process involved the insertion of lithium into electrolytic manganese dioxide with glucose as a mild reductant in an autoclave. Both the hydrothermal temperature and the presence of glucose play the critical roles in determining the final spinel integrity. Particular electrochemical performance has also been systematically explored, and the results show that Al 3+, F - co-substituted spinels have the best combination of initial capacity and capacity retention among all these samples, exhibited the initial capacity of 115 mAh/g and maintained more than 90% of the initial value at the 50th cycle.

Geology of Kilauea volcano

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, R.B.; Trusdell, F.A.

1993-08-01

This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower east rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailedmore » geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. 71 refs., 2 figs.« less

Geology of kilauea volcano

USGS Publications Warehouse

Moore, R.B.; Trusdell, F.A.

1993-01-01

This paper summarizes studies of the structure, stratigraphy, petrology, drill holes, eruption frequency, and volcanic and seismic hazards of Kilauea volcano. All the volcano is discussed, but the focus is on its lower cast rift zone (LERZ) because active exploration for geothermal energy is concentrated in that area. Kilauea probably has several separate hydrothermal-convection systems that develop in response to the dynamic behavior of the volcano and the influx of abundant meteoric water. Important features of some of these hydrothermal-convection systems are known through studies of surface geology and drill holes. Observations of eruptions during the past two centuries, detailed geologic mapping, radiocarbon dating, and paleomagnetic secular-variation studies indicate that Kilauea has erupted frequently from its summit and two radial rift zones during Quaternary time. Petrologic studies have established that Kilauea erupts only tholeiitic basalt. Extensive ash deposits at Kilauea's summit and on its LERZ record locally violent, but temporary, disruptions of local hydrothermal-convection systems during the interaction of water or steam with magma. Recent drill holes on the LERZ provide data on the temperatures of the hydrothermal-convection systems, intensity of dike intrusion, porosity and permeability, and an increasing amount of hydrothermal alteration with depth. The prehistoric and historic record of volcanic and seismic activity indicates that magma will continue to be supplied to deep and shallow reservoirs beneath Kilauea's summit and rift zones and that the volcano will be affected by eruptions and earthquakes for many thousands of years. ?? 1993.

Hydrothermal plume anomalies over the southwest Indian ridge: magmatic control

NASA Astrophysics Data System (ADS)

Yue, X.; Li, H.; Tao, C.; Ren, J.; Zhou, J.; Chen, J.; Chen, S.; Wang, Y.

2017-12-01

Here we firstly reported the extensive survey results of the hydrothermal activity along the ultra-slow spreading southwest Indian ridge (SWIR). The study area is located at segment 27, between the Indomed and Gallieni transform faults, SWIR. The seismic crustal thickness reaches 9.5km in this segment (Li et al., 2015), which is much thicker than normal crustal. The anomaly thickened crust could be affected by the Crozet hotspot or highly focused melt delivery from the mantle. The Duanqiao hydrothermal field was reported at the ridge valley of the segment by Tao et al (2009). The Deep-towed Hydrothermal Detection System (DHDS) was used to collect information related with hydrothermal activity, like temperature, turbidity, oxidation-reduction potential (ORP) and seabed types. There are 15 survey lines at the interval of 2 to 3 km which are occupied about 1300 km2 in segment 27. After processing the raw data, including wiping out random noise points, 5-points moving average processing and subtracting the ambient, we got anomalous Nephelometric Turbidity Units values (ΔNTU). And dE/dt was used to identify the ORP anomalous as the raw data is easily influenced by electrode potentials drifting (Baker et al., 2016). According to the results of water column turbidity and ORP distributions, we confirmed three hydrothermal anomaly fields named A1, A2 and A3. The three fields are all located in the western part of the segment. The A1 field lies on the ridge valley, west side of Duanqiao field. The A2 and A3 field lie on the northern and southern of the ridge valley, respectively. We propose that recent magmatic activity probably focus on the western part of segment 27.And the extensive distribution of hydrothermal plume in the segment is the result of the discrete magma intrusion. References Baker E T, et al. How many vent fields? New estimates of vent field populations on ocean ridges from precise mapping of hydrothermal discharge locations. EPSL, 2016, 449:186-196. Li J, et al. Seismic observation of an extremely magmatic accretion at the ultraslow spreading Southwest Indian Ridge. GRL, 2015, 42:2656-2663. Tao C, Wu G, Ni J, et al. New hydrothermal fields found along the SWIR during the Legs 5-7 of the Chinese DY115-20 Expedition. AGU 2009.

Hydrothermal systems on Mars: an assessment of present evidence

NASA Technical Reports Server (NTRS)

Farmer, J. D.

1996-01-01

Hydrothermal processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and hydrothermal processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient hydrothermal systems on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for hydrothermal mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient hydrothermal systems would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of hydrothermal systems being dominated by magma-cryosphere interactions. Given the smaller gravitational field, declining atmospheric pressure, and widespread, permeable megaregolith on Mars, volatile outgassing and magmatic cooling would have been more effective than on Earth. Thus, hydrothermal systems are likely to have had much lower average surface temperatures than comparable geological settings on Earth. The likely predominance of basaltic crust on Mars suggests that hydrothermal fluids and associated deposits should be enriched in Fe, Mg, Si and Ca, with surficial deposits being dominated by lower temperature, mixed iron oxide and carbonate mineralogies.

Hydrothermal systems on Mars: an assessment of present evidence.

PubMed

Farmer, J D

1996-01-01

Hydrothermal processes have been suggested to explain a number of observations for Mars, including D/H ratios of water extracted from Martian meteorites, as a means for removing CO2 from the Martian atmosphere and sequestering it in the crust as carbonates, and as a possible origin for iron oxide-rich spectral units on the floors of some rifted basins (chasmata). There are numerous examples of Martian channels formed by discharges of subsurface water near potential magmatic heat sources, and hydrothermal processes have also been proposed as a mechanism for aquifer recharge needed to sustain long term erosion of sapping channels. The following geological settings have been identified as targets for ancient hydrothermal systems on Mars: channels located along the margins of impact crater melt sheets and on the slopes of ancient volcanoes; chaotic and fretted terranes where shallow subsurface heat sources are thought to have interacted with ground ice; and the floors of calderas and rifted basins (e.g. chasmata). On Earth, such geological environments are often a locus for hydrothermal mineralization. But we presently lack the mineralogical information needed for a definitive evaluation of hypotheses. A preferred tool for identifying minerals by remote sensing methods on Earth is high spatial resolution, hyperspectral, near-infrared spectroscopy, a technique that has been extensively developed by mineral explorationists. Future efforts to explore Mars for ancient hydrothermal systems would benefit from the application of methods developed by the mining industry to look for similar deposits on Earth. But Earth-based exploration models must be adapted to account for the large differences in the climatic and geological history of Mars. For example, it is likely that the early surface environment of Mars was cool, perhaps consistently below freezing, with the shallow portions of hydrothermal systems being dominated by magma-cryosphere interactions. Given the smaller gravitational field, declining atmospheric pressure, and widespread, permeable megaregolith on Mars, volatile outgassing and magmatic cooling would have been more effective than on Earth. Thus, hydrothermal systems are likely to have had much lower average surface temperatures than comparable geological settings on Earth. The likely predominance of basaltic crust on Mars suggests that hydrothermal fluids and associated deposits should be enriched in Fe, Mg, Si and Ca, with surficial deposits being dominated by lower temperature, mixed iron oxide and carbonate mineralogies.

Low-Temperature Synthesis of Vertically Align ZnO Layer on ITO Glass: The Role of Seed Layer and Hydrothermal Process

NASA Astrophysics Data System (ADS)

Sholehah, Amalia; Achmad, NurSumiati; Dimyati, Arbi; Dwiyanti, Yanyan; Partuti, Tri

2017-05-01

ZnO thin layer has a broad potential application in optoelectronic devices. In the present study, vertically align ZnO layers on ITO glass were synthesized using wet chemical method. The seed layers were prepared using electrodeposition method at 3°C. After that, the growing process was carried out using chemical bath deposition (CBD) at 90°C. To improve the structural property of the ZnO layers, hydrothermal technique was used subsequently. Results showed that seeding layer has a great influence on the physical properties of the ZnO layers. Moreover, hydrothermal process conducted after the ZnO growth can enhance the morphological property of the layers. From the experiments, it is found that the ZnO layers has diameter of ∼60 nm with increasing thickness from ∼0.8 to 1.2 μm and band-gap energies of ∼3.2 eV.

Lithium isotope as a proxy for water/rock interaction between hydrothermal fluids and oceanic crust at Milos, Greece

NASA Astrophysics Data System (ADS)

Lou, U.-Lat; You, Chen-Feng; Wu, Shein-Fu; Chung, Chuan-Hsiung

2014-05-01

Hydrothermal activity at Milos in the Aegean island (Greece) is mainly located at rather shallow depth (about 5 m). It is interesting to compare these chemical compositions and the evolution processes of the hydrothermal fluids at deep sea hydrothermal vents in Mid-ocean Ridge (MOR). Lithium (Li) is a highly mobile element and its isotopic composition varies at different geological settings. Therefore, Li and its isotope could be used as an indicator for many geochemical processes. Since 6Li preferential retained in the mineral phase where 7Li is leached into fluid phase during basalt alteration, the Li isotopic fractionation between the rocks and the fluids reflect sensitively the degree of water-rock interaction. In this study, Bio-Rad AG-50W X8 cation exchange resin was used for purifying the hydrothermal fluids to separate Li from other matrix elements. The Li isotopic composition (δ7Li) was determined by Multi-collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) with precision better than 0.2‰ (2σ, n=20). The Li concentration in the hydrothermal fluids falls between 0.02 to 10.31 mM. The δ7Li values vary from +1.9 to +29.7‰, indicating significant seawater contamination have occurred. These hydrothermal fluids fit well with seawater and brine two end-member binary mixing model. During phase separation, lithium, boron, chlorine, iodine, bromine, sodium and potassium were enriched in the brine phase. On the other hand, aluminum, sulphur and iron were enriched in the vapor phase. There is no significant isotope fractionation between the two phases. The water/rock ratio (W/R) calculated is low (about 1.5 to 1.8) for the Milos fluids, restricted seawater recharge into the oceanic crust. Moreover, the oceanic crust in the region becomes less altered since the W/R is low. The δ7Li value of the hydrothermal fluids can be used as a sensitive tool for studying water-rock interaction.

Dynamic triggering

USGS Publications Warehouse

Hill, David P.; Prejean, Stephanie; Schubert, Gerald

2015-01-01

Dynamic stresses propagating as seismic waves from large earthquakes trigger a spectrum of responses at global distances. In addition to locally triggered earthquakes in a variety of tectonic environments, dynamic stresses trigger tectonic (nonvolcanic) tremor in the brittle–plastic transition zone along major plate-boundary faults, activity changes in hydrothermal and volcanic systems, and, in hydrologic domains, changes in spring discharge, water well levels, soil liquefaction, and the eruption of mud volcanoes. Surface waves with periods of 15–200 s are the most effective triggering agents; body-wave trigger is less frequent. Triggering dynamic stresses can be < 1 kPa.

Hydrothermal carbonization of autoclaved municipal solid waste pulp and anaerobically treated pulp digestate

USDA-ARS?s Scientific Manuscript database

In this study, the autoclaved organic fraction of municipal solid waste pulp (OFMSW) and the digestate from OFMSW pulp after anaerobic digestion (AD) were processed by hydrothermal carbonization (HTC) at 200, 250, and 300 °C for 30 min and 2 h. The focus of this work was to evaluate the potential fo...

Effects of iron-containing minerals on hydrothermal reactions of ketones

NASA Astrophysics Data System (ADS)

Yang, Ziming; Gould, Ian R.; Williams, Lynda B.; Hartnett, Hilairy E.; Shock, Everett L.

2018-02-01

Hydrothermal organic transformations occurring in geochemical processes are influenced by the surrounding environments including rocks and minerals. This work is focused on the effects of five common minerals on reactions of a model ketone substrate, dibenzylketone (DBK), in an experimental hydrothermal system. Ketones play a central role in many hydrothermal organic functional group transformations, such as those converting hydrocarbons to oxygenated compounds; however, how these minerals control the hydrothermal chemistry of ketones is poorly understood. Under the hydrothermal conditions of 300 °C and 70 MPa for up to 168 h, we observed that, while quartz (SiO2) and corundum (Al2O3) had no detectable effect on the hydrothermal reactions of DBK, iron-containing minerals, such as hematite (Fe2O3), magnetite (Fe3O4), and troilite (synthetic FeS), accelerated the reaction of DBK by up to an order of magnitude. We observed that fragmentation products, such as toluene and bibenzyl, dominated in the presence of hematite or magnetite, while use of troilite gave primarily the reduction products, e.g., 1, 3-diphenyl-propane and 1, 3-diphenyl-2-propanol. The roles of the three iron minerals in these transformations were further explored by (1) control experiments with various mineral surface areas, (2) measuring H2 in hydrothermal solutions, and (3) determining hydrogen balance among the organic products. These results suggest the reactions catalyzed by iron oxides (hematite and magnetite) are promoted mainly by the mineral surfaces, whereas the sulfide mineral (troilite) facilitated the reduction of ketone in the reaction solution. Therefore, this work not only provides a useful chemical approach to study and uncover complicated hydrothermal organic-mineral interactions, but also fosters a mechanistic understanding of ketone reactions in the deep carbon cycle.

Metagenomic resolution of microbial functions in deep-sea hydrothermal plumes across the Eastern Lau Spreading Center

PubMed Central

Anantharaman, Karthik; Breier, John A; Dick, Gregory J

2016-01-01

Microbial processes within deep-sea hydrothermal plumes affect ocean biogeochemistry on global scales. In rising hydrothermal plumes, a combination of microbial metabolism and particle formation processes initiate the transformation of reduced chemicals like hydrogen sulfide, hydrogen, methane, iron, manganese and ammonia that are abundant in hydrothermal vent fluids. Despite the biogeochemical importance of this rising portion of plumes, it is understudied in comparison to neutrally buoyant plumes. Here we use metagenomics and bioenergetic modeling to describe the abundance and genetic potential of microorganisms in relation to available electron donors in five different hydrothermal plumes and three associated background deep-sea waters from the Eastern Lau Spreading Center located in the Western Pacific Ocean. Three hundred and thirty one distinct genomic ‘bins' were identified, comprising an estimated 951 genomes of archaea, bacteria, eukarya and viruses. A significant proportion of these genomes is from novel microorganisms and thus reveals insights into the energy metabolism of heretofore unknown microbial groups. Community-wide analyses of genes encoding enzymes that oxidize inorganic energy sources showed that sulfur oxidation was the most abundant and diverse chemolithotrophic microbial metabolism in the community. Genes for sulfur oxidation were commonly present in genomic bins that also contained genes for oxidation of hydrogen and methane, suggesting metabolic versatility in these microbial groups. The relative diversity and abundance of genes encoding hydrogen oxidation was moderate, whereas that of genes for methane and ammonia oxidation was low in comparison to sulfur oxidation. Bioenergetic-thermodynamic modeling supports the metagenomic analyses, showing that oxidation of elemental sulfur with oxygen is the most dominant catabolic reaction in the hydrothermal plumes. We conclude that the energy metabolism of microbial communities inhabiting rising hydrothermal plumes is dictated by the underlying plume chemistry, with a dominant role for sulfur-based chemolithoautotrophy. PMID:26046257

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high-frequency gas monitoring.

PubMed

de Moor, J Maarten; Aiuppa, A; Avard, G; Wehrmann, H; Dunbar, N; Muller, C; Tamburello, G; Giudice, G; Liuzzo, M; Moretti, R; Conde, V; Galle, B

2016-08-01

Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high-frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO 2 -rich gas (CO 2 /S total  > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur-rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is ~8-10 km deep, whereas the shallow magmatic gas source is at ~3-5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H 2 S/SO 2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO 2 and H 2 S/SO 2  > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H 2 S/SO 2  < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high-temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity.

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high‐frequency gas monitoring

PubMed Central

Aiuppa, A.; Avard, G.; Wehrmann, H.; Dunbar, N.; Muller, C.; Tamburello, G.; Giudice, G.; Liuzzo, M.; Moretti, R.; Conde, V.; Galle, B.

2016-01-01

Abstract Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high‐frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO2‐rich gas (CO2/Stotal > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur‐rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is ~8–10 km deep, whereas the shallow magmatic gas source is at ~3–5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H2S/SO2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO2 and H2S/SO2 > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H2S/SO2 < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high‐temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity. PMID:27774371

Turmoil at Turrialba Volcano (Costa Rica): Degassing and eruptive processes inferred from high-frequency gas monitoring

NASA Astrophysics Data System (ADS)

de Moor, J. Maarten; Aiuppa, A.; Avard, G.; Wehrmann, H.; Dunbar, N.; Muller, C.; Tamburello, G.; Giudice, G.; Liuzzo, M.; Moretti, R.; Conde, V.; Galle, B.

2016-08-01

Eruptive activity at Turrialba Volcano (Costa Rica) has escalated significantly since 2014, causing airport and school closures in the capital city of San José. Whether or not new magma is involved in the current unrest seems probable but remains a matter of debate as ash deposits are dominated by hydrothermal material. Here we use high-frequency gas monitoring to track the behavior of the volcano between 2014 and 2015 and to decipher magmatic versus hydrothermal contributions to the eruptions. Pulses of deeply derived CO2-rich gas (CO2/Stotal > 4.5) precede explosive activity, providing a clear precursor to eruptive periods that occurs up to 2 weeks before eruptions, which are accompanied by shallowly derived sulfur-rich magmatic gas emissions. Degassing modeling suggests that the deep magmatic reservoir is 8-10 km deep, whereas the shallow magmatic gas source is at 3-5 km. Two cycles of degassing and eruption are observed, each attributed to pulses of magma ascending through the deep reservoir to shallow crustal levels. The magmatic degassing signals were overprinted by a fluid contribution from the shallow hydrothermal system, modifying the gas compositions, contributing volatiles to the emissions, and reflecting complex processes of scrubbing, displacement, and volatilization. H2S/SO2 varies over 2 orders of magnitude through the monitoring period and demonstrates that the first eruptive episode involved hydrothermal gases, whereas the second did not. Massive degassing (>3000 T/d SO2 and H2S/SO2 > 1) followed, suggesting boiling off of the hydrothermal system. The gas emissions show a remarkable shift to purely magmatic composition (H2S/SO2 < 0.05) during the second eruptive period, reflecting the depletion of the hydrothermal system or the establishment of high-temperature conduits bypassing remnant hydrothermal reservoirs, and the transition from phreatic to phreatomagmatic eruptive activity.

Morphology-preserving chemical conversion of bioorganic and inorganic templates

NASA Astrophysics Data System (ADS)

Vernon, Jonathan Paul

The generation of nanostructured assemblies with complex (three-dimensional, 3D) self-assembled morphologies and with complex (multicomponent) tailorable inorganic compositions is of considerable technological and scientific interest. This dissertation demonstrates self-assembled 3D organic templates of biogenic origin can be converted into replicas comprised of numerous other functional nanocrystalline inorganic materials. Nature provides a spectacular variety of biologically-assembled 3D organic structures with intricate, hierarchical (macro-to-micro-to-nanoscale) morphologies. Such processing on readily-available structurally complex templates provides a framework for chemical conversion of synthetic organic templates and, potentially, production of organic/inorganic composites. Four specific research thrusts are detailed in this document. First, chemical conversion of a nanostructured bioorganic template into a multicomponent oxide compound (tetragonal BaTiO3) via SSG coating and subsequent morphology-preserving microwave hydrothermal processing is demonstrated. Second, morphology-preserving chemical conversion of bioorganic templates into hierarchical photoluminescent microparticles is demonstrated to reveal both the dramatic change in properties such processing can provide, and the potential utility of chemically transformed templates in anti-counterfeiting / authentication applications. Third, determination of the reaction mechanism(s) for morphology-preserving microwave hydrothermal conversion of TiO2 to BaTiO3, through Au inert markers on single crystal rutile titania, is detailed. Finally, utilization of constructive coating techniques (SSG) and moderate temperature (< 500°C) heat treatments to modify and replicate structural color is coupled with deconstructive focused ion beam microsurgery to prepare samples for microscale structure interrogation. Specifically, the effects of coating thickness and composition on reflection spectra of structurally colored templates are examined. Also, the effects of the replacement of natural material with higher index of refraction inorganic materials on optical properties are discussed. The three processing research thrusts constituting chapters 1, 2 and 4 take advantage of moderate temperature processing to ensure nanocrystalline materials, either for shape preservation or to prevent scattering in optical applications. The research thrust detailed in chapter 3 examines hydrothermal conversion of TiO2 to BaTiO3, not only to identify the reaction mechanism(s) involved in hydrothermal conversion under morphology-preserving conditions, but also to introduce inert marker experiments to the field of microwave hydrothermal processing.

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 the other distinct characteristics, such as the B-δ 11 B and B- 10Be systematics, of arc lavas. Finally, the mobilization of B, Cs, Pb, and light REEs relative to heavy REEs in the hydrothermal fluids fractionate the ratios of B/Be, B/Nb, Cs/Rb, Pb/Ce, La/Ba and LREE/HREE, which behave conservatively during normal magmatic processes. These results demonstrate that the composition of slab-derived fluids has great implications for the recycling of elements; not only in arc magmas but also in mantle plumes.

Methane- and Hydrogen-Influenced Microbial Communities in Hydrothermal Plumes above the Atlantis Massif, Mid Atlantic Ridge

NASA Astrophysics Data System (ADS)

Stewart, C. L.; Schrenk, M.

2017-12-01

Ultramafic-hosted hydrothermal systems associated with slow-spreading mid ocean ridges emit copious amounts of hydrogen and methane into the deep-sea, generated through a process known as serpentinization. Hydrothermal plumes carrying the reduced products of water-rock interaction dissipate and mix with deep seawater, and potentially harbor microbial communities adapted to these conditions. Methane and hydrogen enriched hydrothermal plumes were sampled from 3 sites near the Atlantis Massif (30°N, Mid Atlantic Ridge) during IODP Expedition 357 and used to initiate cultivation experiments targeting methanotrophic and hydrogenotrophic microorganisms. One set of experiments incubated the cultures at in situ hydrostatic pressures and gas concentrations resulting in the enrichment of gammaproteobacterial assemblages, including Marinobacter spp. That may be involved in hydrocarbon degradation. A second set of experiments pursued the anaerobic enrichment of microbial communities on solid media, resulting in the enrichment of alphaproteobacteria related to Ruegeria. The most prodigious growth in both case occurred in methane-enriched media, which may play a role as both an energy and carbon source. Ongoing work is evaluating the physiological characteristics of these isolates, including their metabolic outputs under different physical-chemical conditions. In addition to providing novel isolates from hydrothermal habitats near the Lost City Hydrothermal Field, these experiments will provide insight into the ecology of microbial communities from serpentinization influenced hydrothermal systems that may aid in future exploration of these sites.

Integrated thermal infrared imaging and Structure-from-Motion photogrametry to map apparent temperature and radiant hydrothermal heat flux at Mammoth Mountain, CA USA

USGS Publications Warehouse

Lewis, Aaron; George Hilley,; Lewicki, Jennifer L.

2015-01-01

This work presents a method to create high-resolution (cm-scale) orthorectified and georeferenced maps of apparent surface temperature and radiant hydrothermal heat flux and estimate the radiant hydrothermal heat emission rate from a study area. A ground-based thermal infrared (TIR) camera was used to collect (1) a set of overlapping and offset visible imagery around the study area during the daytime and (2) time series of co-located visible and TIR imagery at one or more sites within the study area from pre-dawn to daytime. Daytime visible imagery was processed using the Structure-from-Motion photogrammetric method to create a digital elevation model onto which pre-dawn TIR imagery was orthorectified and georeferenced. Three-dimensional maps of apparent surface temperature and radiant hydrothermal heat flux were then visualized and analyzed from various computer platforms (e.g., Google Earth, ArcGIS). We demonstrate this method at the Mammoth Mountain fumarole area on Mammoth Mountain, CA. Time-averaged apparent surface temperatures and radiant hydrothermal heat fluxes were observed up to 73.7 oC and 450 W m-2, respectively, while the estimated radiant hydrothermal heat emission rate from the area was 1.54 kW. Results should provide a basis for monitoring potential volcanic unrest and mitigating hydrothermal heat-related hazards on the volcano.

Hydrothermal Testing of K Basin Sludge and N Reactor Fuel at Sludge Treatment Project Operating Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delegard, Calvin H.; Schmidt, Andrew J.; Thornton, Brenda M.

The Sludge Treatment Project (STP), managed for the U. S. DOE by Fluor Hanford (FH), was created to design and operate a process to eliminate uranium metal from K Basin sludge prior to packaging for Waste Isolation Pilot Plant (WIPP). The STP process uses high temperature liquid water to accelerate the reaction, produce uranium dioxide from the uranium metal, and safely discharge the hydrogen. Under nominal process conditions, the sludge will be heated in pressurized water at 185°C for as long as 72 hours to assure the complete reaction (corrosion) of up to 0.25-inch diameter uranium metal pieces. Under contractmore » to FH, the Pacific Northwest National Laboratory (PNNL) conducted bench-scale testing of the STP hydrothermal process in November and December 2006. Five tests (~50 ml each) were conducted in sealed, un-agitated reaction vessels under the hydrothermal conditions (e.g., 7 to 72 h at 185°C) of the STP corrosion process using radioactive sludge samples collected from the K East Basin and particles/coupons of N Reactor fuel also taken from the K Basins. The tests were designed to evaluate and understand the chemical changes that may be occurring and the effects that any changes would have on sludge rheological properties. The tests were not designed to evaluate engineering aspects of the process. The hydrothermal treatment affected the chemical and physical properties of the sludge. In each test, significant uranium compound phase changes were identified, resulting from dehydration and chemical reduction reactions. Physical properties of the sludge were significantly altered from their initial, as-settled sludge values, including, shear strength, settled density, weight percent water, and gas retention.« less

Steam jacket dynamics in underground coal gasification

NASA Astrophysics Data System (ADS)

Otto, Christopher; Kempka, Thomas

2017-04-01

Underground coal gasification (UCG) has the potential to increase the world-wide hydrocarbon reserves by utilization of deposits not economically mineable by conventional methods. In this context, UCG involves combusting coal in-situ to produce a high-calorific synthesis gas, which can be applied for electricity generation or chemical feedstock production. Apart from high economic potentials, in-situ combustion may cause environmental impacts such as groundwater pollution by by-product leakage. In order to prevent or significantly mitigate these potential environmental concerns, UCG reactors are generally operated below hydrostatic pressure to limit the outflow of UCG process fluids into overburden aquifers. This pressure difference effects groundwater inflow into the reactor and prevents the escape of product gas. In the close reactor vicinity, fluid flow determined by the evolving high reactor temperatures, resulting in the build-up of a steam jacket. Numerical modeling is one of the key components to study coupled processes in in-situ combustion. We employed the thermo-hydraulic numerical simulator MUFITS (BINMIXT module) to address the influence of reactor pressure dynamics as well as hydro-geological coal and caprock parameters on water inflow and steam jacket dynamics. The US field trials Hanna and Hoe Creek (Wyoming) were applied for 3D model validation in terms of water inflow matching, whereby the good agreement between our modeling results and the field data indicates that our model reflects the hydrothermal physics of the process. In summary, our validated model allows a fast prediction of the steam jacket dynamics as well as water in- and outflows, required to avoid aquifer contamination during the entire life cycle of in-situ combustion operations.

Seismological evidence for an along-axis hydrothermal flow at the Lucky Strike hydrothermal vents site

NASA Astrophysics Data System (ADS)

Rai, A.; Wang, H.; Singh, S. C.; Crawford, W. C.; Escartin, J.; Cannat, M.

2010-12-01

Hydrothermal circulation at ocean spreading centres plays fundamental role in crustal accretion process, heat extraction from the earth and helps to maintain very rich ecosystem in deep Ocean. Recently, it has been suggested that hydrothermal circulation is mainly along the ridge axis at fast spreading centres above along axis melt lens (AMC). Using a combination of micro-earthquake and seismic reflection data, we show that the hydrothermal circulation at the Lucky Strike segment of slow spreading Mid-Atlantic Ridge is also along axis in a narrow (~1 km) zone above a wide (2-3 km) AMC. We find that the seismicity mainly lies above the seismically imaged 3 km wide 7 km long melt lens at 3.2 km depth. We observe a vertical plume of seismicity above a weak AMC reflection just north of the hydrothermal vent fields that initiates just above the AMC and continues to the seafloor. This zone is collocated with active rifting of the seafloor in the neo-volcanic zone. Beneath the hydrothermal vents sites, where a strong melt lens is imaged, the seismicity initiates at 500 m above the AMC and continues to the seafloor. Just south of the hydrothermal field, where the AMC is widest and strongest, the seismicity band lies 500 m above the melt lens in a 800 m thick zone, which does not continue to the seafloor. The presence the weak melt lens reflection could be due to a cooled and crystallised AMC (mush) that permits the penetration of hydrothermal fluids down to the top of the AMC indicated by seismicity plume and might be the in-flow zone for hydrothermal circulation. The strong AMC reflection could be due to fresh supply of melt in the AMC (pure melt), which has pushed the cracking front 500 m above the AMC. Beneath the hydrothermal fields, the strong AMC reflection and seismicity 500 above the AMC to the seafloor could represent cracking along the up-flow zone. The 800 m thick zone of seismicity above the pure melt zone could be the zone of hydrothermal cracking zone. We do not observe any seismicity along the main bounding faults. These results suggest that the hydrothermal flow is mainly along the ridge axis in a narrow zone above the AMC, even when the AMC only 7 km long.

Surfactant-assisted hydrothermal crystallization of nanostructured lithium metasilicate (Li{sub 2}SiO{sub 3}) hollow spheres: (I) Synthesis, structural and microstructural characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortiz-Landeros, J.; Departamento de Ingenieria Metalurgica, Escuela Superior de Ingenieria Quimica e Industrias Extractivas, IPN, UPALM, Av. Instituto Politecnico Nacional s/n, CP 07738, Mexico DF; Contreras-Garcia, M.E.

Lithium metasilicate (Li{sub 2}SiO{sub 3}) was successfully synthesized using a hydrothermal process in the presence of different surfactants with cationic, non-ionic and anionic characters. The samples obtained were compared to a sample prepared by the conventional solid-state reaction method. The structural and microstructural characterizations of different Li{sub 2}SiO{sub 3} powders were performed using various techniques. Diffraction analyses revealed the successful crystallization of pure Li{sub 2}SiO{sub 3} single phase by hydrothermal technique, even without further heat-treatments and independent of the surfactant used. Electron microscopy analyses revealed that Li{sub 2}SiO{sub 3} powders were composed of uniform micrometric particles with a hollow spheremore » morphology and nanostructured walls. Finally, different thermal analyses showed that Li{sub 2}SiO{sub 3} samples preserved their structure and microstructure after further thermal treatments. Specific aspects regarding the formation mechanism of the spherical aggregates under hydrothermal conditions are discussed, and there is a special emphasis on the effect of the synthesis pathway on the morphological characteristics. -- Graphical abstract: Li{sub 2}SiO{sub 3} was synthesized using a hydrothermal process in the presence of different surfactants. Li{sub 2}SiO{sub 3} powders were composed of uniform micrometric particles with a hollow sphere morphology and nanostructured walls. Display Omitted Highlights: {yields} Pure Li{sub 2}SiO{sub 3} was synthesized by the hydrothermal method. {yields} Surfactant addition produced microstructural and morphological variations. {yields} TEM reveled the generation of nanostructured hollow spheres.« less

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.

Using Image Analysis to Explore Changes In Bacterial Mat Coverage at the Base of a Hydrothermal Vent within the Caldera of Axial Seamount

NASA Astrophysics Data System (ADS)

Knuth, F.; Crone, T. J.; Marburg, A.

2017-12-01

The Ocean Observatories Initiative's (OOI) Cabled Array is delivering real-time high-definition video data from an HD video camera (CAMHD), installed at the Mushroom hydrothermal vent in the ASHES hydrothermal vent field within the caldera of Axial Seamount, an active submarine volcano located approximately 450 kilometers off the coast of Washington at a depth of 1,542 m. Every three hours the camera pans, zooms and focuses in on nine distinct scenes of scientific interest across the vent, producing 14-minute-long videos during each run. This standardized video sampling routine enables scientists to programmatically analyze the content of the video using automated image analysis techniques. Each scene-specific time series dataset can service a wide range of scientific investigations, including the estimation of bacterial flux into the system by quantifying chemosynthetic bacterial clusters (floc) present in the water column, relating periodicity in hydrothermal vent fluid flow to earth tides, measuring vent chimney growth in response to changing hydrothermal fluid flow rates, or mapping the patterns of fauna colonization, distribution and composition across the vent over time. We are currently investigating the seventh scene in the sampling routine, focused on the bacterial mat covering the seafloor at the base of the vent. We quantify the change in bacterial mat coverage over time using image analysis techniques, and examine the relationship between mat coverage, fluid flow processes, episodic chimney collapse events, and other processes observed by Cabled Array instrumentation. This analysis is being conducted using cloud-enabled computer vision processing techniques, programmatic image analysis, and time-lapse video data collected over the course of the first CAMHD deployment, from November 2015 to July 2016.

Faults and Fractures in the Subseafloor Environment tell a Different Story than They do at the Seafloor

NASA Astrophysics Data System (ADS)

Hayman, N. W.

2018-05-01

Planetary studies can benefit from a lesson learned in the research of Mid-Ocean Ridges, wherein the subsurface view of faulting and fracturing contrasts with surface observations, important for the dynamics and chemistry of hydrothermal systems.

DIAPHANE: muon tomography applied to volcanoes, civil engineering, archaelogy

NASA Astrophysics Data System (ADS)

Marteau, J.; de Bremond d'Ars, J.; Gibert, D.; Jourde, K.; Ianigro, J.-C.; Carlus, B.

2017-02-01

Muography techniques applied to geological structures greatly improved in the past ten years. Recent applications demonstrate the interest of the method not only to perform structural imaging but also to monitor the dynamics of inner movements like magma ascent inside volcanoes or density variations in hydrothermal systems. Muography time-resolution has been studied thanks to dedicated experiments, e.g. in a water tower tank. This paper presents the activities of the DIAPHANE collaboration between particle- and geo-physicists and the most recent results obtained in the field of volcanology, with a focus on the main target, the Soufrière of Guadeloupe active volcano. Special emphasis is given on the monitoring of the dome's inner volumes opacity variations, that could be ascribed to the hydrothermal system dynamics (vaporization of inner liquid water in coincidence with the appearance of new fumaroles at the summit). I also briefly present results obtained in the fields of civil engineering (study of urban underground tunnels) and archaelogy (greek tumulus scanning).

Hydrothermal effect and mechanical stress properties of carboxymethylcellulose based hydrogel food packaging.

PubMed

Gregorova, Adriana; Saha, Nabanita; Kitano, Takeshi; Saha, Petr

2015-03-06

The PVP-CMC hydrogel film is biodegradable, transparent, flexible, hygroscopic and breathable material which can be used as a food packaging material. The hygroscopic character of CMC and PVP plays a big role in the changing of their mechanical properties where load carrying capacity is one of important criteria for packaging materials. This paper reports about the hydrothermal effect on the mechanical and viscoelastic properties of neat CMC, and PVP-CMC (20:80) hydrogel films under the conditions of combined multiple stress factors such as temperature, time, load, frequency and humidity. The dry films were studied by transient and dynamic oscillatory experiments using dynamic mechanical analyser combined with relative humidity chamber (DMA-RH). The mechanical properties of PVP-CMC hydrogel film at room temperature (25 °C), in the range of 0-30%RH remain steady. The 20 wt% of PVP in PVP-CMC hydrogel increases the stiffness of CMC from 2940 to 3260 MPa at 25 °C and 10%RH. Copyright © 2014 Elsevier Ltd. All rights reserved.

Low-temperature crystallization of anodized TiO2 nanotubes at the solid-gas interface and their photoelectrochemical properties

NASA Astrophysics Data System (ADS)

Liu, Jing; Liu, Zhaoyue; Zhang, Tierui; Zhai, Jin; Jiang, Lei

2013-06-01

TiO2 nanotubular arrays formed by electrochemical anodization have attracted significant attention for photoelectrochemical applications that utilize solar energy. However, the as-anodized TiO2 nanotubes are amorphous, and need to be crystallized by high-temperature thermal annealing. Herein, we describe a low-temperature hydrothermal solid-gas route to crystallize TiO2 nanotubes. In this process, the as-anodized TiO2 hydroxo nanotubes are dehydrated to yield anatase phase via solid-gas interface reaction in an autoclave at a temperature of less than 180 °C. The solid-gas interface reaction alleviates the collapse of as-anodized TiO2 nanotubes during hydrothermal process efficiently. Compared with the common thermal annealing at the same temperature but at atmospheric pressure, the hydrothermal route improves the photocurrent density of TiO2 nanotubes by ~10 times in KOH electrolyte. The duration of the hydrothermal reaction has a substantial effect on the photoelectrochemical properties of TiO2 nanotubes, which is ascribed to the synergetic effect between the crystallization and structural evolution. Electron donors can further suppress the charge recombination in the low-temperature crystallized TiO2 nanotubes and boost the photocurrent density by ~120%.TiO2 nanotubular arrays formed by electrochemical anodization have attracted significant attention for photoelectrochemical applications that utilize solar energy. However, the as-anodized TiO2 nanotubes are amorphous, and need to be crystallized by high-temperature thermal annealing. Herein, we describe a low-temperature hydrothermal solid-gas route to crystallize TiO2 nanotubes. In this process, the as-anodized TiO2 hydroxo nanotubes are dehydrated to yield anatase phase via solid-gas interface reaction in an autoclave at a temperature of less than 180 °C. The solid-gas interface reaction alleviates the collapse of as-anodized TiO2 nanotubes during hydrothermal process efficiently. Compared with the common thermal annealing at the same temperature but at atmospheric pressure, the hydrothermal route improves the photocurrent density of TiO2 nanotubes by ~10 times in KOH electrolyte. The duration of the hydrothermal reaction has a substantial effect on the photoelectrochemical properties of TiO2 nanotubes, which is ascribed to the synergetic effect between the crystallization and structural evolution. Electron donors can further suppress the charge recombination in the low-temperature crystallized TiO2 nanotubes and boost the photocurrent density by ~120%. Electronic supplementary information (ESI) available: Morphology images of TiO2 nanotubular arrays crystallized by hydrothermal solid-liquid reaction at 130 °C, 160 °C and 180 °C for 4 h. Cross-sectional image of TiO2 nanotubular arrays prepared by anodizing Ti foil at 20 V for 20 min in 0.5 wt% HF solution followed by drying in air at 100 °C for 1 h; Photocurrent density-potential curves of TiO2 nanotubular arrays crystallized by thermal annealing at 450 °C and atmospheric pressure for 4 h. See DOI: 10.1039/c3nr01286g

Bacterial Diversity and Biogeochemistry of Two Marine Shallow-Water Hydrothermal Systems off Dominica (Lesser Antilles).

PubMed

Pop Ristova, Petra; Pichler, Thomas; Friedrich, Michael W; Bühring, Solveig I

2017-01-01

Shallow-water hydrothermal systems represent extreme environments with unique biogeochemistry and high biological productivity, at which autotrophic microorganisms use both light and chemical energy for the production of biomass. Microbial communities of these ecosystems are metabolically diverse and possess the capacity to transform a large range of chemical compounds. Yet, little is known about their diversity or factors shaping their structure or how they compare to coastal sediments not impacted by hydrothermalism. To this end, we have used automated ribosomal intergenic spacer analysis (ARISA) and high-throughput Illumina sequencing combined with porewater geochemical analysis to investigate microbial communities along geochemical gradients in two shallow-water hydrothermal systems off the island of Dominica (Lesser Antilles). At both sites, venting of hydrothermal fluids substantially altered the porewater geochemistry by enriching it with silica, iron and dissolved inorganic carbon, resulting in island-like habitats with distinct biogeochemistry. The magnitude of fluid flow and difference in sediment grain size, which impedes mixing of the fluids with seawater, were correlated with the observed differences in the porewater geochemistry between the two sites. Concomitantly, individual sites harbored microbial communities with a significantly different community structure. These differences could be statistically linked to variations in the porewater geochemistry and the hydrothermal fluids. The two shallow-water hydrothermal systems of Dominica harbored bacterial communities with high taxonomical and metabolic diversity, predominated by heterotrophic microorganisms associated with the Gammaproteobacterial genera Pseudomonas and Pseudoalteromonas , indicating the importance of heterotrophic processes. Overall, this study shows that shallow-water hydrothermal systems contribute substantially to the biogeochemical heterogeneity and bacterial diversity of coastal sediments.

The metatranscriptome of a deep-sea hydrothermal plume is dominated by water column methanotrophs and lithotrophs

PubMed Central

Lesniewski, Ryan A; Jain, Sunit; Anantharaman, Karthik; Schloss, Patrick D; Dick, Gregory J

2012-01-01

Microorganisms mediate geochemical processes in deep-sea hydrothermal vent plumes, which are a conduit for transfer of elements and energy from the subsurface to the oceans. Despite this important microbial influence on marine geochemistry, the ecology and activity of microbial communities in hydrothermal plumes is largely unexplored. Here, we use a coordinated metagenomic and metatranscriptomic approach to compare microbial communities in Guaymas Basin hydrothermal plumes to background waters above the plume and in the adjacent Carmen Basin. Despite marked increases in plume total RNA concentrations (3–4 times) and microbially mediated manganese oxidation rates (15–125 times), plume and background metatranscriptomes were dominated by the same groups of methanotrophs and chemolithoautotrophs. Abundant community members of Guaymas Basin seafloor environments (hydrothermal sediments and chimneys) were not prevalent in the plume metatranscriptome. De novo metagenomic assembly was used to reconstruct genomes of abundant populations, including Marine Group I archaea, Methylococcaceae, SAR324 Deltaproteobacteria and SUP05 Gammaproteobacteria. Mapping transcripts to these genomes revealed abundant expression of genes involved in the chemolithotrophic oxidation of ammonia (amo), methane (pmo) and sulfur (sox). Whereas amo and pmo gene transcripts were abundant in both plume and background, transcripts of sox genes for sulfur oxidation from SUP05 groups displayed a 10–20-fold increase in plumes. We conclude that the biogeochemistry of Guaymas Basin hydrothermal plumes is mediated by microorganisms that are derived from seawater rather than from seafloor hydrothermal environments such as chimneys or sediments, and that hydrothermal inputs serve as important electron donors for primary production in the deep Gulf of California. PMID:22695860

The metatranscriptome of a deep-sea hydrothermal plume is dominated by water column methanotrophs and lithotrophs.

PubMed

Lesniewski, Ryan A; Jain, Sunit; Anantharaman, Karthik; Schloss, Patrick D; Dick, Gregory J

2012-12-01

Microorganisms mediate geochemical processes in deep-sea hydrothermal vent plumes, which are a conduit for transfer of elements and energy from the subsurface to the oceans. Despite this important microbial influence on marine geochemistry, the ecology and activity of microbial communities in hydrothermal plumes is largely unexplored. Here, we use a coordinated metagenomic and metatranscriptomic approach to compare microbial communities in Guaymas Basin hydrothermal plumes to background waters above the plume and in the adjacent Carmen Basin. Despite marked increases in plume total RNA concentrations (3-4 times) and microbially mediated manganese oxidation rates (15-125 times), plume and background metatranscriptomes were dominated by the same groups of methanotrophs and chemolithoautotrophs. Abundant community members of Guaymas Basin seafloor environments (hydrothermal sediments and chimneys) were not prevalent in the plume metatranscriptome. De novo metagenomic assembly was used to reconstruct genomes of abundant populations, including Marine Group I archaea, Methylococcaceae, SAR324 Deltaproteobacteria and SUP05 Gammaproteobacteria. Mapping transcripts to these genomes revealed abundant expression of genes involved in the chemolithotrophic oxidation of ammonia (amo), methane (pmo) and sulfur (sox). Whereas amo and pmo gene transcripts were abundant in both plume and background, transcripts of sox genes for sulfur oxidation from SUP05 groups displayed a 10-20-fold increase in plumes. We conclude that the biogeochemistry of Guaymas Basin hydrothermal plumes is mediated by microorganisms that are derived from seawater rather than from seafloor hydrothermal environments such as chimneys or sediments, and that hydrothermal inputs serve as important electron donors for primary production in the deep Gulf of California.

Bacterial Diversity and Biogeochemistry of Two Marine Shallow-Water Hydrothermal Systems off Dominica (Lesser Antilles)

PubMed Central

Pop Ristova, Petra; Pichler, Thomas; Friedrich, Michael W.; Bühring, Solveig I.

2017-01-01

Shallow-water hydrothermal systems represent extreme environments with unique biogeochemistry and high biological productivity, at which autotrophic microorganisms use both light and chemical energy for the production of biomass. Microbial communities of these ecosystems are metabolically diverse and possess the capacity to transform a large range of chemical compounds. Yet, little is known about their diversity or factors shaping their structure or how they compare to coastal sediments not impacted by hydrothermalism. To this end, we have used automated ribosomal intergenic spacer analysis (ARISA) and high-throughput Illumina sequencing combined with porewater geochemical analysis to investigate microbial communities along geochemical gradients in two shallow-water hydrothermal systems off the island of Dominica (Lesser Antilles). At both sites, venting of hydrothermal fluids substantially altered the porewater geochemistry by enriching it with silica, iron and dissolved inorganic carbon, resulting in island-like habitats with distinct biogeochemistry. The magnitude of fluid flow and difference in sediment grain size, which impedes mixing of the fluids with seawater, were correlated with the observed differences in the porewater geochemistry between the two sites. Concomitantly, individual sites harbored microbial communities with a significantly different community structure. These differences could be statistically linked to variations in the porewater geochemistry and the hydrothermal fluids. The two shallow-water hydrothermal systems of Dominica harbored bacterial communities with high taxonomical and metabolic diversity, predominated by heterotrophic microorganisms associated with the Gammaproteobacterial genera Pseudomonas and Pseudoalteromonas, indicating the importance of heterotrophic processes. Overall, this study shows that shallow-water hydrothermal systems contribute substantially to the biogeochemical heterogeneity and bacterial diversity of coastal sediments. PMID:29255454

Optimization of hydrothermal pretreatment of lignocellulosic biomass in the bioethanol production process.

PubMed

Nitsos, Christos K; Matis, Konstantinos A; Triantafyllidis, Kostas S

2013-01-01

The natural resistance to enzymatic deconstruction exhibited by lignocellulosic materials has designated pretreatment as a key step in the biological conversion of biomass to ethanol. Hydrothermal pretreatment in pure water represents a challenging approach because it is a method with low operational costs and does not involve the use of organic solvents, difficult to handle chemicals, and "external" liquid or solid catalysts. In the present work, a systematic study has been performed to optimize the hydrothermal treatment of lignocellulosic biomass (beech wood) with the aim of maximizing the enzymatic digestibility of cellulose in the treated solids and obtaining a liquid side product that could also be utilized for the production of ethanol or valuable chemicals. Hydrothermal treatment experiments were conducted in a batch-mode, high-pressure reactor under autogeneous pressure at varying temperature (130-220 °C) and time (15-180 min) regimes, and at a liquid-to-solid ratio (LSR) of 15. The intensification of the process was expressed by the severity factor, log R(o). The major changes induced in the solid biomass were the dissolution/removal of hemicellulose to the process liquid and the partial removal and relocation of lignin on the external surface of biomass particles in the form of recondensed droplets. The above structural changes led to a 2.5-fold increase in surface area and total pore volume of the pretreated biomass solids. The enzymatic hydrolysis of cellulose to glucose increased from less than 7 wt% for the parent biomass to as high as 70 wt% for the treated solids. Maximum xylan recovery (60 wt%) in the hydrothermal process liquid was observed at about 80 wt% hemicellulose removal; this was accomplished by moderate treatment severities (log R(o)=3.8-4.1). At higher severities (log R(o)=4.7), xylose degradation products, mainly furfural and formic acid, were the predominant chemicals formed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Discovery of a magma chamber and faults beneath a Mid-Atlantic Ridge hydrothermal field.

PubMed

Singh, Satish C; Crawford, Wayne C; Carton, Hélène; Seher, Tim; Combier, Violaine; Cannat, Mathilde; Pablo Canales, Juan; Düsünür, Doga; Escartin, Javier; Miranda, J Miguel

2006-08-31

Crust at slow-spreading ridges is formed by a combination of magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate and fast-spreading centres, but it has been difficult to image such magma chambers beneath slow-spreading centres, owing to rough seafloor topography and associated seafloor scattering. In the absence of any images of magma chambers or of subsurface near-axis faults, it has been difficult to characterize the interplay of magmatic and tectonic processes in crustal accretion and hydrothermal circulation at slow-spreading ridges. Here we report the presence of a crustal magma chamber beneath the slow-spreading Lucky Strike segment of the Mid-Atlantic Ridge. The reflection from the top of the magma chamber, centred beneath the Lucky Strike volcano and hydrothermal field, is approximately 3 km beneath the sea floor, 3-4 km wide and extends up to 7 km along-axis. We suggest that this magma chamber provides the heat for the active hydrothermal vent field above it. We also observe axial valley bounding faults that seem to penetrate down to the magma chamber depth as well as a set of inward-dipping faults cutting through the volcanic edifice, suggesting continuous interactions between tectonic and magmatic processes.

Investigating Crustal Scale Fault Systems Controlling Volcanic and Hydrothermal Fluid Processes in the South-Central Andes, First Results from a Magnetotelluric Survey

NASA Astrophysics Data System (ADS)

Pearce, R.; Mitchell, T. M.; Moorkamp, M.; Araya, J.; Cembrano, J. M.; Yanez, G. A.; Hammond, J. O. S.

2017-12-01

At convergent plate boundaries, volcanic orogeny is largely controlled by major thrust fault systems that act as magmatic and hydrothermal fluid conduits through the crust. In the south-central Andes, the volcanically and seismically active Tinguiririca and Planchon-Peteroa volcanoes are considered to be tectonically related to the major El Fierro thrust fault system. These large scale reverse faults are characterized by 500 - 1000m wide hydrothermally altered fault cores, which possess a distinct conductive signature relative to surrounding lithology. In order to establish the subsurface architecture of these fault systems, such conductivity contrasts can be detected using the magnetotelluric method. In this study, LEMI fluxgate-magnetometer long-period and Metronix broadband MT data were collected at 21 sites in a 40km2 survey grid that surrounds this fault system and associated volcanic complexes. Multi-remote referencing techniques is used together with robust processing to obtain reliable impedance estimates between 100 Hz and 1,000s. Our preliminary inversion results provide evidence of structures within the 10 - 20 km depth range that are attributed to this fault system. Further inversions will be conducted to determine the approximate depth extent of these features, and ultimately provide constraints for future geophysical studies aimed to deduce the role of these faults in volcanic orogeny and hydrothermal fluid migration processes in this region of the Andes.

Two-Dimensional NMR Evidence for Cleavage of Lignin and Xylan Substituents in Wheat Straw Through Hydrothermal Pretreatment and Enzymatic Hydrolysis

Treesearch

Daniel J. Yelle; Prasad Kaparaju; Christopher G. Hunt; Kolby Hirth; Hoon Kim; John Ralph; Claus Felby

2012-01-01

Solution-state two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy of plant cell walls is a powerful tool for characterizing changes in cell wall chemistry during the hydrothermal pretreatment process of wheat straw for second-generation bioethanol production. One-bond 13C-1H NMR correlation spectroscopy, via...

Template-free synthesis of ZnWO{sub 4} powders via hydrothermal process in a wide pH range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hojamberdiev, Mirabbos, E-mail: mirabbos_uz@yahoo.com; Zhu, Gangqiang; Xu, Yunhua

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 revealedmore » 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.« less

Influence of sward maturity and pre-conditioning temperature on the energy production from grass silage through the integrated generation of solid fuel and biogas from biomass (IFBB): 2. Properties of energy carriers and energy yield.

PubMed

Richter, F; Fricke, T; Wachendorf, M

2011-04-01

In order to determine influencing parameters on energy production of the IFBB process, herbage from a lowland hay meadow (Arrhenaterion) was sampled and ensiled at eight dates between 27 April and 21 June 2007. The silage from each date was processed in six IFBB treatments with and without hydrothermal conditioning at different temperatures. Methane yields and higher heating values were determined and an energy balance was calculated with whole-crop digestion (WCD) of the silage as reference system. Maximum net energy yields were 10.2 MWh ha(-1) for the IFBB treatment without hydrothermal conditioning and 9.0 MWh ha(-1) for the treatment with hydrothermal conditioning at 50 °C. WCD achieved a maximum net energy yield of 3.7 MWh ha(-1). Energy conversion efficiency ranged from 0.24 to 0.54 and was predicted with high accuracy by temperature of hydrothermal conditioning as well as concentration of neutral detergent fibre and dry matter in the silage (R(2)=0.90). Copyright © 2011 Elsevier Ltd. All rights reserved.

Spiculosiphon oceana (Foraminifera) a new bio-indicator of acidic environments related to fluid emissions of the Zannone Hydrothermal Field (central Tyrrhenian Sea).

PubMed

Di Bella, Letizia; Ingrassia, Michela; Frezza, Virgilio; Chiocci, Francesco L; Pecci, Raffaella; Bedini, Rossella; Martorelli, Eleonora

2018-05-01

The new record of a shallow-water submarine hydrothermal field (<150 m w.d.) in the western Mediterranean Sea (Tyrrhenian Sea, Italy) allows us to study CO 2 fluid impact on benthic foraminifers. Benthic foraminifers calcification process is sensitive to ocean acidification and to local chemical and physical parameters of seawater and pore water. Thus, foraminifers can record specific environmental conditions related to hydrothermal fluids, but at present their response to such activity is poorly defined. The major outcome of this study is the finding of a very uncommon taxon for the Mediterranean Sea, i.e., the Spiculosiphon oceana, a giant foraminifer agglutinating spicules of sponges. This evidence, along with the strong decrease of calcareous tests in the foraminiferal assemblages associated to hydrothermal activity, provides new insights on the meiofauna living in natural stressed environment. In particular, observations obtained from this study allow us to consider S. oceana a potential tolerant species of high CO 2 concentrations (about 2-4 times higher than the normal marine values) and a proxy of acidic environments as well as of recent ocean acidification processes. Copyright © 2018 Elsevier Ltd. All rights reserved.

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.

Syntheses of nanocrystalline BaTiO3 and their optical properties

NASA Astrophysics Data System (ADS)

Yu, J.; Chu, J.; Zhang, M.

Stoichiometric and titanium-excess nanocrystalline barium titanates were synthesized using a hydrothermal process at various hydrothermal temperatures and with further heat treatment at 500 °C and 900 °C. Owing to the different process conditions, the excess titanium exists in different states and configurations within the nanocrystalline BaTiO3 matrix; this was demonstrated by X-ray diffraction, Raman scattering, and photoluminescence. In these nanocrystalline BaTiO3, the 590, 571, 543 and 694 nm light emission bands were observed; mechanisms leading to such emissions were also discussed.

New technology for recyclingmaterials from oily cold rollingmill sludge

NASA Astrophysics Data System (ADS)

Liu, Bo; Zhang, Shen-gen; Tian, Jian-jun; Pan, De-an; Meng, Ling; Liu, Yang

2013-12-01

Oily cold rolling mill (CRM) sludge is one of metallurgical industry solid wastes. The recycle of these wastes can not only protect the environment but also permit their reutilization. In this research, a new process of "hydrometallurgical treatment + hydrothermal synthesis" was investigated for the combined recovery of iron and organic materials from oily CRM sludge. Hydrometallurgical treatment, mainly including acid leaching, centrifugal separation, neutralization reaction, oxidizing, and preparation of hydrothermal reaction precursor, was first utilized for processing the sludge. Then, micaceous iron oxide (MIO) pigment powders were prepared through hydrothermal reaction of the obtained precursor in alkaline media. The separated organic materials can be used for fuel or chemical feedstock. The quality of the prepared MIO pigments is in accordance with the standards of MIO pigments for paints (ISO 10601-2007). This clean, effective, and economical technology offers a new way to recycle oily CRM sludge.

Numerical Study of Hydrothermal Wave Suppression in Thermocapillary Flow Using a Predictive Control Method

NASA Astrophysics Data System (ADS)

Muldoon, F. H.

2018-04-01

Hydrothermal waves in flows driven by thermocapillary and buoyancy effects are suppressed by applying a predictive control method. Hydrothermal waves arise in the manufacturing of crystals, including the "open boat" crystal growth process, and lead to undesirable impurities in crystals. The open boat process is modeled using the two-dimensional unsteady incompressible Navier-Stokes equations under the Boussinesq approximation and the linear approximation of the surface thermocapillary force. The flow is controlled by a spatially and temporally varying heat flux density through the free surface. The heat flux density is determined by a conjugate gradient optimization algorithm. The gradient of the objective function with respect to the heat flux density is found by solving adjoint equations derived from the Navier-Stokes ones in the Boussinesq approximation. Special attention is given to heat flux density distributions over small free-surface areas and to the maximum admissible heat flux density.

EVALUATION OF LOW-SUN ILLUMINATED LANDSAT-4 THEMATIC MAPPER DATA FOR MAPPING HYDROTHERMALLY ALTERED ROCKS IN SOUTHERN NEVADA.

USGS Publications Warehouse

Podwysocki, Melvin H.; Power, Marty S.; Salisbury, Jack; Jones, O.D.

1984-01-01

Landsat-4 Thematic Mapper (TM) data of southern Nevada collected under conditions of low-angle solar illumination were digitally processed to identify hydroxyl-bearing minerals commonly associated with hydrothermal alteration in volcanic terrains. Digital masking procedures were used to exclude shadow areas and vegetation and thus to produce a CRC image suitable for testing the new TM bands as a means to map hydrothermally altered rocks. Field examination of a masked CRC image revealed that several different types of altered rocks displayed hues associated with spectral characteristics common to hydroxyl-bearing minerals. Several types of unaltered rocks also displayed similar hues.

Low-temperature hydrothermal synthesis of ZnO nanorods: Effects of zinc salt concentration, various solvents and alkaline mineralizers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Edalati, Khatereh, E-mail: kh_ed834@stu.um.ac.ir; Shakiba, Atefeh; Vahdati-Khaki, Jalil

2016-02-15

Highlights: • We synthesized ZnO nanorods by a simple hydrothermal process at 60 °C. • Effects of zinc salt concentration, solvent and alkaline mineralizer was studied. • Increasing concentration of zinc salt changed ZnO nucleation system. • NaOH yielded better results in the production of nanorods in both solvents. • Methanol performed better in the formation of nanorods using the two mineralizers. - Abstract: ZnO has been produced using various methods in the solid, gaseous, and liquid states, and the hydrothermal synthesis at low temperatures has been shown to be an environmentally-friendly one. The current work utilizes a low reactionmore » temperature (60 °C) for the simple hydrothermal synthesis of ZnO nanorod morphologies. Furthermore, the effects of zinc salt concentration, solvent type and alkaline mineralizer type on ZnO nanorods synthesis at a low reaction temperature by hydrothermal processing was studied. Obtained samples were analyzed using X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Increasing the concentration of the starting zinc salt from 0.02 to 0.2 M changed ZnO nucleation system from the homogeneous to the heterogeneous state. The XRD results confirmed the production hexagonal ZnO nanostructures of with a crystallite size of 40.4 nm. Varying the experimental parameters (mineralizer and solvent) yielded ZnO nanorods with diameters ranging from 90–250 nm and lengths of 1–2 μm.« less

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). Copyright © 2016 Elsevier Ltd. All rights reserved.

Laboratory simulation of hydrothermal petroleum formation from sediment in Escanaba Trough, offshore from northern California

USGS Publications Warehouse

Kvenvolden, K.A.; Rapp, J.B.; Hostettler, F.D.; Rosenbauer, R.J.

1994-01-01

Petroleum associated with sulfide-rich sediment is present in Escanaba Trough at the southern end of the Gorda Ridge spreading axis offshore from northern California within the Exclusive Economic Zone (EEZ) of the U.S. This location and occurrence are important for evaluation of the mineral and energy resource potential of the seafloor under U.S. jurisdiction. In Escanaba Trough, petroleum is believed to be formed by hydrothermal processes acting on mainly terrigenous organic material in Quaternary, river-derived sediment. To attempt to simulate these processes in the laboratory, portions of a Pleistocene gray-green mud, obtained from ??? 1.5 m below the seafloor at a water depth of ??? 3250 m in Escanaba Trough, were heated in the presence of water in four hydrous-pyrolysis experiments conducted at temperatures ranging from 250 to 350??C and at a pressure of 350 bar for 1.0-4.5 days. Distributions of n-alkanes, isoprenoid hydrocarbons, triterpanes, and steranes in the heated samples were compared with those in a sample of hydrothermal petroleum from the same area. Mud samples heated for less than 4.5 days at less than 350??C show changes in some, but not all, molecular marker ratios of organic compounds that are consistent with those expected during hydrothermal petroleum formation. Our results suggest that the organic matter in this type of sediment serves as one possible source for some of the compounds found in the hydrothermal petroleum. ?? 1994.

Experimentally Testing Hydrothermal Vent Origin of Life on Enceladus and Other Icy/Ocean Worlds.

PubMed

Barge, Laura M; White, Lauren M

2017-09-01

We review various laboratory strategies and methods that can be utilized to simulate prebiotic processes and origin of life in hydrothermal vent systems on icy/ocean worlds. Crucial steps that could be simulated in the laboratory include simulations of water-rock chemistry (e.g., serpentinization) to produce hydrothermal fluids, the types of mineral catalysts and energy gradients produced in vent interfaces where hydrothermal fluids interface with the surrounding seawater, and simulations of biologically relevant chemistry in flow-through gradient systems (i.e., far-from-equilibrium experiments). We describe some examples of experimental designs in detail, which are adaptable and could be used to test particular hypotheses about ocean world energetics or mineral/organic chemistry. Enceladus among the ocean worlds provides an ideal test case, since the pressure at the ocean floor is more easily simulated in the lab. Results for Enceladus could be extrapolated with further experiments and modeling to understand other ocean worlds. Key Words: Enceladus-Ocean worlds-Icy worlds-Hydrothermal vent-Iron sulfide-Gradient. Astrobiology 17, 820-833.

Manganese(II)-oxidizing Bacillus spores in Guaymas Basin hydrothermal sediments and plumes.

PubMed

Dick, Gregory J; Lee, Yifan E; Tebo, Bradley M

2006-05-01

Microbial oxidation and precipitation of manganese at deep-sea hydrothermal vents are important oceanic biogeochemical processes, yet nothing is known about the types of microorganisms or mechanisms involved. Here we report isolation of a number of diverse spore-forming Mn(II)-oxidizing Bacillus species from Guaymas Basin, a deep-sea hydrothermal vent environment in the Gulf of California, where rapid microbially mediated Mn(II) oxidation was previously observed. mnxG multicopper oxidase genes involved in Mn(II) oxidation were amplified from all Mn(II)-oxidizing Bacillus spores isolated, suggesting that a copper-mediated mechanism of Mn(II) oxidation could be important at deep-sea hydrothermal vents. Phylogenetic analysis of 16S rRNA and mnxG genes revealed that while many of the deep-sea Mn(II)-oxidizing Bacillus species are very closely related to previously recognized isolates from coastal sediments, other organisms represent novel strains and clusters. The growth and Mn(II) oxidation properties of these Bacillus species suggest that in hydrothermal sediments they are likely present as spores that are active in oxidizing Mn(II) as it emerges from the seafloor.

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

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. Paragenetically-constrained sulphur isotope analyses provide evidence that at MacMillan Pass and in the Red Dog deposits, reduced sulphur was generated during open system diagenesis and euxinic conditions were not present at the time of mineralization. Furthermore, the formation of diagenetic barite provided an important mechanism of sulphur concentration into the host rock. Both features combined to produce an effective metal trap in the sub-surface. Ultimately, interactions between hydrothermal and diagenetic fluids within a permeable, chemically reactive medium contribute to the formation of SHMS deposits. Where these factors align, it is possible to produce world-class ore deposits (e.g. in the Red Dog district). The complex textures that are commonly encountered in these systems are the result of hydrothermal fluids interacting with their host-rocks in a heterogeneous and dynamic physical and chemical environment.

The hydrothermal exploration system on the 'Qianlong2' AUV

NASA Astrophysics Data System (ADS)

Tao, W.; Tao, C.; Jinhui, Z.; Cai, L.; Guoyin, Z.

2016-12-01

ABSTRACT: Qianlong2, is a fully Autonomous Underwater Vehicle (AUV) designed for submarine resources research, especially for polymetallic sulphides, and the survey depths of is up to 4500 m. Qianlong2 had successfully explored hydrothermal vent field on the Southwest Indian Ridge (SWIR), and collected conductance, temperature and depth (CTD), turbidity, and Oxidation-Reduction Potential (ORP) data. It also had mapped precise topography by high resolution side scan sonar (HRBSSS) during every dive; and obtained photographs of sulfide deposits during some dives. Here, we detailedly described the implementation of investigation, data administration, and fast mapping of hydrothermal exploration system by Qianlong2. Giving a description of how to remove the platform magnetic interference by using magnetic data during Qianlong2 spin. Based on comprehensive hydrochemical anomalies, we get a rapid method for finding the localization of hydrothermal vents. Taking one dive as an example, we systemically showed the process about how to analyse hydrothermal survey data and acquire the location results of hydrothermal vents. Considering that this method is effective and can be used in other deep-submergence assets such as human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) during further studies. Finally, we discussed how to promote and optimize the installation and application of those sensors and how to improve Qianlong2's autonomy of investigation.

Quantitative characterization of the aqueous fraction from hydrothermal liquefaction of algae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas

Aqueous streams generated from hydrothermal liquefaction contain approximately 30% of the total carbon present from the algal feed. Hence, this aqueous carbon must be utilized to produce liquid fuels and/or specialty chemicals for economic sustainability of hydrothermal liquefaction on industrial scale. In this study, aqueous fractions produced from the hydrothermal liquefaction of fresh water and saline water algal cultures were analyzed using a wide variety of analytical instruments to determine their compositional characteristics. This study will also inform researchers designing catalysts for down-stream processing such as high-pressure catalytic conversion of organics in aqueous phase, catalytic hydrothermal gasification, and biological conversions.more » Organic chemical compounds present in all eight aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compounds include organic acids, nitrogen compounds and aldehydes/ketones. Conventional gas chromatography and liquid chromatography methods were utilized to quantify the identified compounds. Inorganic species in the aqueous stream of hydrothermal liquefaction of algae were identified using ion chromatography and inductively coupled plasma optical emission spectrometer. The concentrations of organic chemical compounds and inorganic species are reported. The amount quantified carbon ranged from 45 to 72 % of total carbon in the aqueous fractions.« less

Sample Return from Ancient Hydrothermal Springs

NASA Technical Reports Server (NTRS)

Allen, Carlton C.; Oehler, Dorothy Z.

2008-01-01

Hydrothermal spring deposits on Mars would make excellent candidates for sample return. Molecular phylogeny suggests that that life on Earth may have arisen in hydrothermal settings [1-3], and on Mars, such settings not only would have supplied energy-rich waters in which martian life may have evolved [4-7] but also would have provided warm, liquid water to martian life forms as the climate became colder and drier [8]. Since silica, sulfates, and clays associated with hydrothermal settings are known to preserve geochemical and morphological remains of ancient terrestrial life [9-11], such settings on Mars might similarly preserve evidence of martian life. Finally, because formation of hydrothermal springs includes surface and subsurface processes, martian spring deposits would offer the potential to assess astrobiological potential and hydrological history in a variety of settings, including surface mineralized terraces, associated stream deposits, and subsurface environments where organic remains may have been well protected from oxidation. Previous attempts to identify martian spring deposits from orbit have been general or limited by resolution of available data [12-14]. However, new satellite imagery from HiRISE has a resolution of 28 cm/pixel, and based on these new data, we have interpreted several features in Vernal Crater, Arabia Terra as ancient hydrothermal springs [15, 16].

Hydrothermal temperature effect on crystal structures, optical properties and electrical conductivity of ZnO nanostructures

NASA Astrophysics Data System (ADS)

Dhafina, Wan Almaz; Salleh, Hasiah; Daud, Mohd Zalani; Ghazali, Mohd Sabri Mohd; Ghazali, Salmah Mohd

2017-09-01

ZnO is an wide direct band gap semiconductor and possess rich family of nanostructures which turned to be a key role in the nanotechnology field of applications. Hydrothermal method was proven to be simple, robust and low cost among the reported methods to synthesize ZnO nanostructures. In this work, the properties of ZnO nanostructures were altered by varying temperatures of hydrothermal process. The changes in term of morphological, crystal structures, optical properties and electrical conductivity were investigated. A drastic change of ZnO nanostructures morphology and decreases of 002 diffraction peak were observed as the hydrothermal temperature increased. The band gap of samples decreased as the size of ZnO nanostructure increased, whereas the electrical conductivity had no influence on the band gap value but more on the morphology of ZnO nanostructures instead.

Hydrothermal Origin for Carbonate Globules in Martian Meteorite ALH84001: A Terrestrial Analogue from Spitsbergen (Norway)

NASA Technical Reports Server (NTRS)

Treiman, Allan H.; Amundsen, Hans E. F.; Blake, David F.; Bunch, Ted

2002-01-01

Carbonate minerals in the ancient Martian meteorite ALH84001 are the only known solid phases that bear witness to the processing of volatile and biologically critical compounds (CO2, H2O) on early Mars. Similar carbonates have been found in xenoliths and their host basalts from Quaternary volcanic centers in northern Spitsbergen (Norway). These carbonates were deposited by hot (i.e., hydrothermal) waters associated with the volcanic activity. By analogy with the Spitsbergen carbonates, the ALH84001 carbonates were probably also deposited by hot water. Hydrothermal activity was probably common and widespread on Early Mars, which featured abundant basaltic rocks, water as ice or liquid, and heat from volcanos and asteroid impacts. On Earth, descendants of the earliest life forms still prefer hydrothermal environments, which are now shown to have been present on early Mars.

Hydrothermal alteration of sediments associated with surface emissions from the Cerro Prieto geothermal field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valette-Silver, J.N.; Esquer P., I.; Elders, W.A.

1981-01-01

A study of the mineralogical changes associated with these hydrothermal vents was initiated with the aim of developing possible exploration tools for geothermal resources. The Cerro Prieto reservoir has already been explored by extensive deep drilling so that relationships between surface manifestations and deeper hydrothermal processes could be established directly. Approximately 120 samples of surface sediments were collected both inside and outside of the vents. The mineralogy of the altered sediments studied appears to be controlled by the type of emission. A comparison between the changes in mineralogy due to low temperature hydrothermal activity in the reservoir, seen in samplesmore » from boreholes, and mineralogical changes in the surface emission samples shows similar general trends below 180 C: increase of quartz, feldspar and illite, with subsequent disappearance of kaolinite, montmorillonite, calcite and dolomite. These mineral assemblages seem to be characteristic products of the discharge from high intensity geothermal fields.« less

Mars weathering analogs - Secondary mineralization in Antarctic basalts

NASA Technical Reports Server (NTRS)

Berkley, J. L.

1982-01-01

Alkalic basalt samples from Ross Island, Antarctica, are evaluated as terrestrial analogs to weathered surface materials on Mars. Secondary alteration in the rocks is limited to pneumatolytic oxidation of igneous minerals and glass, rare groundmass clay and zeolite mineralization, and hydrothermal minerals coating fractures and vesicle surfaces. Hydrothermal mineral assemblages consist mainly of K-feldspar, zeolites (phillipsite and chabazite), calcite, and anhydrite. Low alteration rates are attributed to cold and dry environmental factors common to both Antarctica and Mars. It is noted that mechanical weathering (aeolian abrasion) of Martian equivalents to present Antarctic basalts would yield minor hydrothermal minerals and local surface fines composed of primary igneous minerals and glass but would produce few hydrous products, such as palagonite, clay or micas. It is thought that leaching of hydrothermal vein minerals by migrating fluids and redeposition in duricrust deposits may represent an alternate process for incorporating secondary minerals of volcanic origin into Martian surface fines.

High-throughput continuous hydrothermal synthesis of nanomaterials (part II): unveiling the as-prepared CexZryYzO2-δ phase diagram.

PubMed

Quesada-Cabrera, Raul; Weng, Xiaole; Hyett, Geoff; Clark, Robin J H; Wang, Xue Z; Darr, Jawwad A

2013-09-09

High-throughput continuous hydrothermal flow synthesis was used to manufacture 66 unique nanostructured oxide samples in the Ce-Zr-Y-O system. This synthesis approach resulted in a significant increase in throughput compared to that of conventional batch or continuous hydrothermal synthesis methods. The as-prepared library samples were placed into a wellplate for both automated high-throughput powder X-ray diffraction and Raman spectroscopy data collection, which allowed comprehensive structural characterization and phase mapping. The data suggested that a continuous cubic-like phase field connects all three Ce-Zr-O, Ce-Y-O, and Y-Zr-O binary systems together with a smooth and steady transition between the structures of neighboring compositions. The continuous hydrothermal process led to as-prepared crystallite sizes in the range of 2-7 nm (as determined by using the Scherrer equation).

Hydrothermal plumes over spreading-center axes: Global distributions and geological inferences

NASA Astrophysics Data System (ADS)

Baker, Edward T.; German, Christopher R.; Elderfield, Henry

Seafloor hydrothermal circulation is the principal agent of energy and mass exchange between the ocean and the earth's crust. Discharging fluids cool hot rock, construct mineral deposits, nurture biological communities, alter deep-sea mixing and circulation patterns, and profoundly influence ocean chemistry and biology. Although the active discharge orifices themselves cover only a minuscule percentage of the ridge-axis seafloor, the investigation and quantification of their effects is enhanced as a consequence of the mixing process that forms hydrothermal plumes. Hydrothermal fluids discharged from vents are rapidly diluted with ambient seawater by factors of 104-105 [Lupton et al., 1985]. During dilution, the mixture rises tens to hundreds of meters to a level of neutral buoyancy, eventually spreading laterally as a distinct hydrographic and chemical layer with a spatial scale of tens to thousands of kilometers [e.g., Lupton and Craig, 1981; Baker and Massoth, 1987; Speer and Rona, 1989].

Hierarchical Na-doped cubic ZrO{sub 2} synthesis by a simple hydrothermal route and its application in biodiesel production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lara-García, Hugo A.; Romero-Ibarra, Issis C.; Pfeiffer, Heriberto, E-mail: pfeiffer@iim.unam.mx

Hierarchical growth of cubic ZrO{sub 2} phase was successfully synthesized via a simple hydrothermal process in the presence of different surfactants (cationic, non-ionic and anionic) and sodium hydroxide. The structural and microstructural characterizations of different ZrO{sub 2} powders were performed using various techniques, such as X-ray diffraction, transmission electron microscopy, N{sub 2} adsorption–desorption, scanning electron microscopy and infrared. Results indicated that sodium addition stabilized the cubic ZrO{sub 2} phase by a Na-doping process, independently of the surfactant used. In contrast, microstructural characteristics varied as a function of the surfactant and sodium presence. In addition, water vapor (H{sub 2}O) and carbonmore » dioxide (CO{sub 2}) sorption properties were evaluated on ZrO{sub 2} samples. Results evidenced that sample surface reactivity changed as a function of the sodium content. Finally, this surface reactivity was evaluated on the biodiesel transesterification reaction using the different synthesized samples, obtaining yields of 93%. - Graphical abstract: Hierarchical growth of cubic Na-ZrO{sub 2} phase was synthesized by hydrothermal processes in the presence of surfactants and sodium. Sodium addition stabilized the cubic phase by a Na-doping process, while the microstructural characteristics varied with surfactants. Finally, this surface reactivity was evaluated on the biodiesel transesterification reaction. - Highlights: • Cubic-ZrO{sub 2} phase was synthesized via a simple hydrothermal process. • ZrO{sub 2} structure and microstructures changed as a function of the surfactant. • Cubic-ZrO{sub 2} phase was evaluated on the biodiesel transesterification reaction.« less

Hydrothermal liquefaction of microalgae to produce biofuels: state of the art and future prospects

NASA Astrophysics Data System (ADS)

Vlaskin, M. S.; Chernova, N. I.; Kiseleva, S. V.; Popel', O. S.; Zhuk, A. Z.

2017-09-01

The article presents a review of the state of the art and lines of research on hydrothermal liquefaction (HTL) of microalgae (MA). The main advantages of this technology for production of biofuel are that it does not require predrying of the feedstock and ensures a relatively high product yield—the ratio of the end product weight to the feedstock weight—owing to the fact that all the microalgal components, viz., lipids, proteins, and carbohydrates, are converted into biofuel. MA hydrothermal liquefaction is considered to be a promising technology for conversion of biomass and is a subject of a series of research studies and, judging by the available publications, the scope of research in this field is expanding currently. However, many significant problems remain unsolved. In particular, an active searched is being conducted for suitable strains that will ensure not only a high lipid yield—necessary to convert microalgae into biodiesel—but also higher biomass productivity and a higher biofuel yield; the chemical reactions that occur during the hydrothermal treatment are being studied; and the effect of significant process variables, such as temperature, heating rate, holdup time at the maximum temperature, biomass concentration in the water suspension, biochemical and elemental compositions of the microalgae, use of catalysts, etc., on the liquefaction processes is being studied. One of the urgent tasks is also the reduction of the nitrogen content in the resulting biofuel. Studies aimed at the development of a continuous process and rational heat-processing plants for thermal microalgal conversion are being conducted to increase the energy efficiency of the HTL process, in particular, to provide the heat recovery and separation of the end product.

Practical development of continuous supercritical fluid process using high pressure and high temperature micromixer

NASA Astrophysics Data System (ADS)

Kawasaki, Shin-Ichiro; Sue, Kiwamu; Ookawara, Ryuto; Wakashima, Yuichiro; Suzuki, Akira

2015-12-01

In the synthesis of metal oxide fine particles by continuous supercritical hydrothermal method, the particle characteristics are greatly affected by not only the reaction conditions (temperature, pressure, residence time, concentration, etc.), but also the heating rate from ambient to reaction temperature. Therefore, the heating method by direct mixing of starting solution at room temperature with supercritical water is a key technology for the particle production having smaller size and narrow distribution. In this paper, mixing engineering study through comparison between conventional T-shaped mixers and recently developed swirl mixers was carried out in the hydrothermal synthesis of NiO nanoparticles from Ni(NO3)2 aqueous solution at 400 °C and 30 MPa. Inner diameter in the mixers and total flow rates were varied. Furthermore, the heating rate was calculated by computational fluid dynamics (CFD) simulation. Relationship between the heating rate and the average particle size were discussed. It was clarified that the miniaturization of mixer inner diameter and the use of the swirl flow were effective for improving mixing performance and contributed to produce small and narrow distribution particle under same experimental condition of flow rate, temperature, pressure, residence time, and concentration of the starting materials. We have focused the mixer optimization due to a difference in fluid viscosity.

Radon surveys and monitoring at active volcanoes: an open window on deep hydrothermal systems and their dynamics

NASA Astrophysics Data System (ADS)

Cigolini, Corrado; Laiolo, Marco; Coppola, Diego

2017-04-01

The behavior of fluids in hydrothermal systems is critical in volcano monitoring and geothermal prospecting. Analyzing the time series of radon emissions on active volcanoes is strategic for detecting and interpreting precursory signals of changes in volcanic activity, eventually leading to eruptions. Radon is a radioactive gas generated from the decay of U bearing rocks, soils and magmas. Although radon has been regarded as a potential precursor of earthquakes, radon anomalies appear to be better suited to forecast volcanic eruptions since we know where paroxysms may occur and we can follow the evolution of volcanic activity. Radon mapping at active volcanoes is also a reliable tool to assess diffuse and concentrated degassing as well as efficiently detecting earthquake-volcano interactions. Systematic radon monitoring has been shown to be a key factor for evaluating the rise of volcanic and hydrothermal fluids. In fact, the decay properties of radon, the duration of radon anomalies together with sampling rates may be cross-checked with the chemistry of hydrothermal fluids (and their transport properties) to constrain fluids ascent rates and to infer the permeability and porosity of rocks in sectors surrounding the active conduits. We hereby further discuss the data of radon surveys and monitoring at Somma-Vesuvius, Stromboli and La Soufrière (Guadeloupe, Lesser Antilles). The integrated analysis of seismic and geochemical data, including radon emissions, may be successfully used in testing temperature distributions and variations of porosity and permeability in volcanic hydrothermal systems and can be used as a proxy to analyze geothermal reservoirs.

Strontium isotope systematics of scheelite and apatite from the Felbertal tungsten deposit, Austria - results of in-situ LA-MC-ICP-MS analysis

NASA Astrophysics Data System (ADS)

Kozlik, Michael; Gerdes, Axel; Raith, Johann G.

2016-02-01

The in-situ Sr isotopic systematics of scheelite and apatite from the Felbertal W deposit and a few regional Variscan orthogneisses ("Zentralgneise") have been determined by LA-MC-ICP-MS. The 87Sr/86Sr ratios of scheelite and apatite from the deposit are highly radiogenic and remarkably scattering. In the early magmatic-hydrothermal scheelite generations (Scheelite 1 and 2) the 87Sr/86Sr ratios range from 0.72078 to 0.76417 and from 0.70724 to 0.76832, respectively. Metamorphic Scheelite 3, formed by recrystallisation and local mobilisation of older scheelite, is characterised by even higher 87Sr/86Sr values between 0.74331 and 0.80689. Statistics allows discriminating the three scheelite generations although there is considerable overlap between Scheelite 1 and 2; they could be mixtures of the same isotopic reservoirs. The heterogeneous and scattering 87Sr/86Sr ratios of the two primary scheelite generations suggest modification of the Sr isotope system due to fluid-rock interaction and isotopic disequilibrium. Incongruent release of 87Sr from micas in the Early Palaeozoic host rocks of the Habach Complex contributed to the solute budget of the hydrothermal fluids and may explain the radiogenic Sr isotope signature of scheelite. Spatially resolved analyses revealed isotopic disequilibrium even on a sub-mm scale within zoned Scheelite 2 crystals indicating scheelite growth in an isotopic dynamical hydrothermal system. Zoned apatite from the W mineralised Early Carboniferous K1-K3 orthogneiss in the western ore field yielded 87Sr/86Sr of 0.72044-0.74514 for the cores and 0.74535-0.77937 for the rims. Values of magmatic apatite cores from the K1-K3 orthogneiss are comparable to those of primary Scheelite 1; they are too radiogenic to be magmatic. The Sr isotopic composition of apatite cores was therefore equally modified during the hydrothermal mineralisation processes, therefore supporting the single-stage genetic model in which W mineralisation is associated with the intrusion of the K1-K3 metagranitoid at Felbertal. The subsequent regional metamorphic overprint of the deposit caused redistribution of 87Sr as a consequence of metamorphic reactions involving Rb and Sr-bearing minerals. Metamorphic Scheelite 3 and apatite rims (e.g., in the K1-K3 orthogneiss) generally became more radiogenic during this process. However, local recrystallisation of primary scheelite under closed conditions (without addition of 87Sr by the metamorphic fluid) is also documented. The latter process resulted in a homogenisation of the isotope composition of Scheelite 3. Further increase in 87Sr/86Sr ratios in Scheelite 3 and apatite rims is attributed to Late Alpine (?) metamorphic recrystallisation and redistribution of 87Sr by metamorphic fluids.

Dependency of outbreaks distribution from insects - defoliators' seasonal development

Treesearch

Valentina Meshkova

2003-01-01

Analysis of data on the population dynamics of foliage browsing insects in time and space was conducted in the Ukraine. For each of the main species, correlation indices were calculated between outbreak characteristics (mean and specific foci area, outbreak probability), weather elements (air temperature, precipitation), indices (hydrothermal coefficient, winter...

Fractional Multistage Hydrothermal Liquefaction of Biomass and Catalytic Conversion into Hydrocarbons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cortright, Randy; Rozmiarek, Robert; Dally, Brice

2017-08-31

The objective of this project was to develop an improved multistage process for the hydrothermal liquefaction (HTL) of biomass to serve as a new front-end, deconstruction process ideally suited to feed Virent’s well-proven catalytic technology, which is already being scaled up. This process produced water soluble, partially de-oxygenated intermediates that are ideally suited for catalytic finishing to fungible distillate hydrocarbons. Through this project, Virent, with its partners, demonstrated the conversion of pine wood chips to drop-in hydrocarbon distillate fuels using a multi-stage fractional conversion system that is integrated with Virent’s BioForming® process. The majority of work was in the liquefactionmore » task and included temperature scoping, solvent optimization, and separations.« less

Hydrothermal reactions of agricultural and food processing wastes in sub- and supercritical water: a review of fundamentals, mechanisms, and state of research.

PubMed

Pavlovič, Irena; Knez, Željko; Škerget, Mojca

2013-08-28

Hydrothermal (HT) reactions of agricultural and food-processing waste have been proposed as an alternative to conventional waste treatment technologies due to allowing several improvements in terms of process performance and energy and economical advantages, especially due to their great ability to process high moisture content biomass waste without prior dewatering. Complex structures of wastes and unique properties of water at higher temperatures and pressures enable a variety of physical-chemical reactions and a wide spectra of products. This paper's aim is to give extensive information about the fundamentals and mechanisms of HT reactions and provide state of the research of agri-food waste HT conversion.

Geochemical and Visual Indicators of Hydrothermal Fluid Flow through a Sediment-Hosted Volcanic Ridge in the Central Bransfield Basin (Antarctica)

PubMed Central

Aquilina, Alfred; Connelly, Douglas P.; Copley, Jon T.; Green, Darryl R. H.; Hawkes, Jeffrey A.; Hepburn, Laura E.; Huvenne, Veerle A. I.; Marsh, Leigh; Mills, Rachel A.; Tyler, Paul A.

2013-01-01

In the austral summer of 2011 we undertook an investigation of three volcanic highs in the Central Bransfield Basin, Antarctica, in search of hydrothermal activity and associated fauna to assess changes since previous surveys and to evaluate the extent of hydrothermalism in this basin. At Hook Ridge, a submarine volcanic edifice at the eastern end of the basin, anomalies in water column redox potential (Eh) were detected close to the seafloor, unaccompanied by temperature or turbidity anomalies, indicating low-temperature hydrothermal discharge. Seepage was manifested as shimmering water emanating from the sediment and from mineralised structures on the seafloor; recognisable vent endemic fauna were not observed. Pore fluids extracted from Hook Ridge sediment were depleted in chloride, sulfate and magnesium by up to 8% relative to seawater, enriched in lithium, boron and calcium, and had a distinct strontium isotope composition (87Sr/86Sr  = 0.708776 at core base) compared with modern seawater (87Sr/86Sr ≈0.70918), indicating advection of hydrothermal fluid through sediment at this site. Biogeochemical zonation of redox active species implies significant moderation of the hydrothermal fluid with in situ diagenetic processes. At Middle Sister, the central ridge of the Three Sisters complex located about 100 km southwest of Hook Ridge, small water column Eh anomalies were detected but visual observations of the seafloor and pore fluid profiles provided no evidence of active hydrothermal circulation. At The Axe, located about 50 km southwest of Three Sisters, no water column anomalies in Eh, temperature or turbidity were detected. These observations demonstrate that the temperature anomalies observed in previous surveys are episodic features, and suggest that hydrothermal circulation in the Bransfield Strait is ephemeral in nature and therefore may not support vent biota. PMID:23359806

Geochemical features of the geothermal fluids from the Mapamyum non-volcanic geothermal system (Western Tibet, China)

NASA Astrophysics Data System (ADS)

Wang, Peng; Chen, Xiaohong; Shen, Licheng; Wu, Kunyu; Huang, Mingzhi; Xiao, Qiong

2016-06-01

Mapamyum geothermal field (MGF) in western Tibet is one of largest geothermal areas characterized by the occurrence of hydrothermal explosions on the Tibetan Plateau. The geochemical properties of hydrothermal water in the MGF system were investigated to trace the origin of the solutes and to determine the equilibrium temperatures of the feeding reservoir. The study results show that the geochemistry of hydrothermal waters in the MGF system is mainly of the Na-HCO3 type. The chemical components of hydrothermal waters are mainly derived from the minerals in the host rocks (e.g., K-feldspar, albite, Ca-montmorillonite, and Mg-montmorillonite). The hydrothermal waters are slightly supersaturated or undersaturated with respect to aragonite, calcite, dolomite, chalcedony and quartz (saturation indices close to 0), but are highly undersaturated with respect to gypsum and anhydrite (saturation indices < 0). Mixing models and Na-K-Mg ternary diagrams show that strong mixing between cold meteoric water and deeply-seated thermal fluids occurred during the upward flowing process. δD and δ18O data confirm that the meteoric water acts as the water source of the geothermal waters. An 220 °C equilibrated reservoir temperature of hydrothermal spring waters was calculated via both the Na-K-Mg ternary diagrams and the cationic chemical geothermometers. The logpCO2 of hydrothermal waters in the MGF system ranges from - 2.59 to - 0.57 and δ13C of the total dissolved inorganic carbon ranges from - 5.53‰ to - 0.94‰, suggesting that the carrier CO2 in hydrothermal water are mainly of a magmatic or metamorphic CO2 origin.

Hydrothermal processing of duckweed: effect of reaction conditions on product distribution and composition.

PubMed

Duan, Peigao; Chang, Zhoufan; Xu, Yuping; Bai, Xiujun; Wang, Feng; Zhang, Lei

2013-05-01

Influences of operating conditions such as temperature (270-380 °C), time (10-120 min), reactor loading (0.5-5.5 g), and K2CO3 loading (0-50 wt.%) on the product (e.g. crude bio-oil, water soluble, gas and solid residue) distribution from the hydrothermal processing of duckweed were determined. Of the four variables, temperature and K2CO3 loading were always the most influential factors to the relative amount of each component. The presence of K2CO3 is unfavorable for the production of bio-oil and gas. Hydrothermal processing duckweed produces a bio-oil that is enriched in carbon and hydrogen and has reduced levels of O compared with the original duckweed feedstock. The higher heating values of the bio-oil were estimated within the range of 32-36 MJ/kg. Major bio-oil constituents include ketones and their alkylated derivatives, alcohols, heterocyclic nitrogen-containing compounds, saturated fatty acids and hydrocarbons. The gaseous products were mainly CO2 and H2, with lesser amounts of CH4 and CO. Copyright © 2012 Elsevier Ltd. All rights reserved.

Harvesting of Chlorella sorokiniana by co-culture with the filamentous fungus Isaria fumosorosea: A potential sustainable feedstock for hydrothermal gasification.

PubMed

Mackay, Stephen; Gomes, Eduardo; Holliger, Christof; Bauer, Rolene; Schwitzguébel, Jean-Paul

2015-06-01

Despite recent advances in down-stream processing, production of microalgae remains substantially limited because of economical reasons. Harvesting and dewatering are the most energy-intensive processing steps in their production and contribute 20-30% of total operational cost. Bio-flocculation of microalgae by co-cultivation with filamentous fungi relies on the development of large structures that facilitate cost effective harvesting. A yet unknown filamentous fungus was isolated as a contaminant from a microalgal culture and identified as Isaria fumosorosea. Blastospores production was optimized in minimal medium and the development of pellets, possibly lichens, was followed when co-cultured with Chlorella sorokiniana under strict autotrophic conditions. Stable pellets (1-2mm) formed rapidly at pH 7-8, clearing the medium of free algal cells. Biomass was harvested with large inexpensive filters, generating wet slurry suitable for hydrothermal gasification. Nutrient rich brine from the aqueous phase of hydrothermal gasification supported growth of the fungus and may increase the process sustainability. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fracture distribution and porosity in a fault-bound hydrothermal system (Grimsel Pass, Swiss Alps)

NASA Astrophysics Data System (ADS)

Egli, Daniel; Küng, Sulamith; Baumann, Rahel; Berger, Alfons; Baron, Ludovic; Herwegh, Marco

2017-04-01

The spatial distribution, orientation and continuity of brittle and ductile structures strongly control fluid pathways in a rock mass by joining existing pores and creating new pore space (fractures, joints) but can also act as seals to fluid flow (e.g. ductile shear zones, clay-rich fault gouges). In long-lived hydrothermal systems, permeability and the related fluid flow paths are therefore dynamic in space and time. Understanding the evolution and behaviour of naturally porous and permeable rock masses is critical for the successful exploration and sustainable exploitation of hydrothermal systems and can advance methods for planning and implementation of enhanced geothermal systems. This study focuses on an active fault-bound hydrothermal system in the crystalline basement of the Aar Massif (hydrothermal field Grimsel Pass, Swiss Alps) that has been exhumed from few kilometres depth and which documents at least 3 Ma of hydrothermal activity. The explored rock unit of the Aar massif is part of the External Crystalline Massifs that hosts a multitude of thermal springs on its southern border in the Swiss Rhône valley and furthermore represents the exhumed equivalent of potentially exploitable geothermal reservoirs in the deep crystalline subsurface of the northern Alpine foreland basin. This study combines structural data collected from a 125 m long drillhole across the hydrothermal zone, the corresponding drill core and surface mapping. Different methods are applied to estimate the porosity and the structural evolution with regard to porosity, permeability and fracture distribution. Analyses are carried out from the micrometre to decametre scale with main focus on the flow path evolution with time. This includes a large variety of porosity-types including fracture-porosity with up to cm-sized aperture down to grain-scale porosity. Main rock types are granitoid host rocks, mylonites, paleo-breccia and recent breccias. The porosity of the host rock as well as the cemented paleo-hydrothermal breccia is typically very low with values <1%. The high volume of mineralized fractures in the paleo-breccia indicates high porosity in former times, which is today closed by newly developed cements. The preservation of such paleo-breccias allow the investigation of contrasts between the fossil porosity/permeability and the present day active flow path, which is defined by fracture porosity that generally follows the regional deformation pattern and forms a wide network of interconnected fractures of variable orientation.

Weathering of post-impact hydrothermal deposits from the Haughton impact structure: implications for microbial colonization and biosignature preservation.

PubMed

Izawa, M R M; Banerjee, Neil R; Osinski, G R; Flemming, R L; Parnell, J; Cockell, C S

2011-01-01

Meteorite impacts are among the very few processes common to all planetary bodies with solid surfaces. Among the effects of impact on water-bearing targets is the formation of post-impact hydrothermal systems and associated mineral deposits. The Haughton impact structure (Devon Island, Nunavut, Canada, 75.2 °N, 89.5 °W) hosts a variety of hydrothermal mineral deposits that preserve assemblages of primary hydrothermal minerals commonly associated with secondary oxidative/hydrous weathering products. Hydrothermal mineral deposits at Haughton include intra-breccia calcite-marcasite vugs, small intra-breccia calcite or quartz vugs, intra-breccia gypsum megacryst vugs, hydrothermal pipe structures and associated surface "gossans," banded Fe-oxyhydroxide deposits, and calcite and quartz veins and coatings in shattered target rocks. Of particular importance are sulfide-rich deposits and their associated assemblage of weathering products. Hydrothermal mineral assemblages were characterized structurally, texturally, and geochemically with X-ray diffraction, micro X-ray diffraction, optical and electron microscopy, and inductively coupled plasma atomic emission spectroscopy. Primary sulfides (marcasite and pyrite) are commonly associated with alteration minerals, including jarosite (K,Na,H(3)O)Fe(3)(SO(4))(2)(OH)(6), rozenite FeSO(4)·4(H(2)O), copiapite (Fe,Mg)Fe(4)(SO(4))(6)(OH)(2)·20(H(2)O), fibroferrite Fe(SO(4))(OH)·5(H(2)O), melanterite FeSO(4)·7(H(2)O), szomolnokite FeSO(4)·H(2)O, goethite α-FeO(OH), lepidocrocite γ-FeO(OH) and ferrihydrite Fe(2)O(3)·0.5(H(2)O). These alteration assemblages are consistent with geochemical conditions that were locally very different from the predominantly circumneutral, carbonate-buffered environment at Haughton. Mineral assemblages associated with primary hydrothermal activity, and the weathering products of such deposits, provide constraints on possible microbial activity in the post-impact environment. The initial period of active hydrothermal circulation produced primary mineral assemblages, including Fe sulfides, and was succeeded by a period dominated by oxidation and low-temperature hydration of primary minerals by surface waters. Active hydrothermal circulation can enable the rapid delivery of nutrients to microbes. Nutrient availability following the cessation of hydrothermal circulation is likely more restricted; therefore, the biological importance of chemical energy from hydrothermal mineral deposits increases with time. Weathering of primary hydrothermal deposits and dissolution and reprecipitation of mobile weathering products also create many potential habitats for endolithic microbes. They also provide a mechanism that may preserve biological materials, potentially over geological timescales. © Mary Ann Liebert, Inc.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, Douglas C.; Hart, Todd R.; Schmidt, Andrew J.

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 wasmore » 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.« less

Manganese Oxidizing Bacteria in Guaymas Basin Hydrothermal Fluids, Sediments, and Plumes

NASA Astrophysics Data System (ADS)

Dick, G. J.; Tebo, B. M.

2002-12-01

The active seafloor hydrothermal system at Guaymas Basin in the Gulf of California is unique in that spreading centers are covered with thick sediments, and hydrothermal fluids are injected into a semi-enclosed basin. This hydrothermal activity is the source of a large input of dissolved manganese [Mn(II)] into Guaymas Basin, and the presence of a large standing stock of particulate manganese in this basin has been taken as evidence for a short residence time of dissolved Mn(II) with respect to oxidation, suggestive of bacterial catalysis. During a recent Atlantis/Alvin expedition (R/V Atlantis Cruise #7, Leg 11, Jim Cowen Chief Scientist), large amounts of particulate manganese oxides were again observed in Guaymas Basin hydrothermal plumes. The goal of the work presented here was to identify bacteria involved in the oxidation of Mn(II) in Guaymas Basin, and to determine what molecular mechanisms drive this process. Culture-based methods were employed to isolate Mn(II)-oxidizing bacteria from Guaymas Basin hydrothermal fluids, sediments, and plumes, and numerous Mn(II)-oxidizing bacteria were identified based on the formation of orange, brown, or black manganese oxides on bacterial colonies on agar plates. The Mn(II)-oxidizing bacteria were able to grow at temperatures from 12 to 50°C, and a selection of the isolates were chosen for phylogenetic (16S rRNA genes) and microscopic characterization. Endospore-forming Bacillus species accounted for many of the Mn(II)-oxidizing isolates obtained from both hydrothermal sediments and plumes, while members of the alpha- and gamma-proteobacteria were also found. Mn(II)-oxidizing enzymes from previously characterized Bacillus spores are known to be active at temperatures greater than 50°C. The presence of Mn(II)-oxidizing spores - some of which are capable of growing at elevated temperatures - in hydrothermal fluids and sediments at Guaymas Basin suggests that Mn(II) oxidation may be occurring immediately or very soon after hydrothermal fluids emerge from the seafloor.

Multi-Sensor Mapping of Diffuse Degassing of C-O-H Compounds in Terrestrial Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Schwandner, F. M.; Shock, E. L.

2004-12-01

In-situ single-sensor detection and mapping of diffuse degassing phenomena in hydrothermal and volcanic areas can be used to elucidate subsurface tectonic structures, assess emission rates, and to monitor emission variability (Williams 1985; Chiodini et al. 1996, Werner et al., 2003). More than one technique has been deployed to measure several gas species simultaneously (e.g., Crenshaw et al. 1982), and correlations of one gas species (usually CO2) with physical parameters like heat flux (Brombach et al., 2001), or with one other gas species (Rn, He) have been demonstrated (Barberi & Carapezza 1994; Williams-Jones et al., 2000). Recently, correlations of multiple gas species with one another were reported (Schwandner et al., 2004), leading to the possibility of quantitative mapping of subsurface hydrothermal chemical processes by simultaneous measurement of reaction partners and products that continuously and diffusely degas. In the present study, we joined a fully-quantitative multi-sensor instrument (Draeger Multiwarn II) to a modified accumulation-chamber sensing method (Chiodini et al., 1996) and measured diffuse degassing of CH4, H2, CO2, CO, and H2S. In this approach, each batch of gas that is recirculated through the detector is simultaneously analyzed by all sensors. To test this approach we chose two magmatically influenced, hydrothermally active areas at Yellowstone National Park (USA): Sylvan Springs and the Greater Obsidian Pool Area. The area near Obsidian Pool was previously studied during a diffuse CO2 degassing campaign (Werner & Brantley, 2004). Preliminary results show that elevated reduced gas emissions appear to be most prominent near hydrothermal pools, whereas CO2-dominated degassing anomalies highlight subsurface tectonic structures. This multimodal distribution allows us to distinguish deep degassing sources (CO2 anomalies) from shallow localized hydrothermal processes (reduced gas anomalies). The results permit us to positively identify and partially map a previously-inferred active lineament in the Obsidian Pool area. In addition, reduced gas data are yielding areal ratio distributions of CO/CO2, H2/CH4, and CO/CH4, that may be indicative of reactions such as the catalytic hydrogenation of CO2 (Sabatier-Process) and of CO (Fischer-Tropsch-Process) within the shallow hydrothermal system. Barberi & Carapezza (1994). Bull. Volcanol. 56(5): 335-342. Brombach, et al. (2001). Geophys. Res. Lett. 28(1): 69-72. Crenshaw et al. (1982). Nature 300: 345-346. Chiodini et al. (1996). Bull. Volcanol. 58(1): 41-50. Schwandner et al. (2004). JGR D 109: D04301, doi:10.1029/2003JD003890. Werner & Brantley (2004) JGR B 105: 10,831-10,846. Werner et al. (2003). Earth Planet. Sci. Lett. 210: 561-577. Williams (1985). Science 229(4713): 551-553. Williams-Jones et al. (2000). Bull. Volcanol. 62: 130-142.

Boehmite nanostructures preparation by hydrothermal method from anodic aluminium oxide membrane.

PubMed

Yang, X; Wang, J Y; Pan, H Y

2009-02-01

Boehmite nanostructures were successfully synthesized from porous anodic aluminium oxide (AAO) membrane by a simple and efficient hydro-thermal method. The experiment used high purity alumina as raw material, and the whole reaction process avoided superfluous impurities to be introduced. Thus, the purity of Boehmite products was ensured. The examinations of the morphology and structure were carried out by atomic force microscope (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Composition of the specimens was analyzed using energy dispersive X-ray spectroscope (EDX) and X-ray diffraction (XRD). Based on these observations the growth process was analyzed.

Identification of Crystalline Minerals in Volcanic Alteration Products and Applications to the Surface of Mars

NASA Technical Reports Server (NTRS)

Bishop, J. L.; Madsen, M. B.; Murad, E.; Wagner, P. A.

2000-01-01

Visible, infrared and Mossbauer spectra have been measured for fine-grained alteration products of volcanic tephra and ash. Comparison of the spectral and chemical properties for different size separates and related samples provides information about the crystalline materials in these samples and how they may have formed. Hydrothermal processes can increase the alteration rates of the primary minerals and glass and provide S, Fe and/or water for formation of sulfates and hydrated minerals. Identification of crystalline alteration minerals on Mars may indicate hydrothermal alteration and sites of interesting geologic processes.

Degassing of metals and metalloids from erupting seamount and mid-ocean ridge volcanoes: Observations and predictions

NASA Astrophysics Data System (ADS)

Rubin, Ken

1997-09-01

Recently, it has been reported that the element polonium degasses from mid-ocean ridge and seamount volcanoes during eruptions. Published and new observations on other volatile metal and metalloid elements can also be interpreted as indicating significant degassing of magmatic vapors during submarine eruptions. This process potentially plays an important role in the net transfer of chemical elements from erupting volcanoes to seawater in addition to that arising from sea floor hydrothermal systems. In this paper, a framework is constructed for predicting and assessing semiquantitatively the potential magnitude and chemical fingerprints in the water column of metal and metalloid degassing using (1) predictions from a summary of element volatilities during mafic subaerial volcanism worldwide and (2) limited data from submarine volcanic effusives. The latter include analyses of polonium and trace metals in near-volcano water masses sampled following a submarine eruption at Loihi seamount, Hawaii (1000 m bsl) in 1996. The element volatility predictions and observations show good agreement, considering the limited dataset. Some of the highest volatility main group and transition element enrichments in seawater over Loihi are predicted by the degassing mass transfer model I present. When expanded to cover all submarine volcanic activity, it is predicted that exit fluxes of these elements are up to 10 2-10 3 greater by degassing than by normal MOR hydrothermalism. In contrast, MOR exit fluxes of low volatility alkali and alkaline earth elements are likely 10 2-10 6 greater from hydrothermal inputs. Degassing inputs to the ocean are probably highly episodic, occurring almost entirely during eruptions; these are times of enhanced and abnormal hydrothermalism as well. Although major hydrothermal and degassing events may not be chemically recognizable in real water masses as wholly distinct entities, it is nevertheless possible to predict to what extent each process flavors the effluents of the other. Degassing at mid-ocean ridges may explain a variety of observations previously ascribed to complexities occurring during hydrothermal venting and/or fluid ascent in the buoyant hydrothermal plumes above ridges.

Geochemical features of sulfides from the Deyin-1 hydrothermal field at the southern Mid-Atlantic Ridge near 15°S

NASA Astrophysics Data System (ADS)

Wang, Shujie; Li, Huaiming; Zhai, Shikui; Yu, Zenghui; Cai, Zongwei

2017-12-01

In this study, geochemical compositions of elements in sulfide samples collected from the Deyin-1 hydrothermal field near the 15°S southern Mid-Atlantic Ridge (SMAR) were analyzed by the X-ray fluorescence spectrometry (XRF) and inductively coupled plasma mass spectrometry (ICP-MS) to examine the enrichment regulations of ore-forming elements and hydrothermal mineralization. These sulfide precipitates can be classified macroscopically into three types: Fe-rich sulfide, Fe-Cu-rich sulfide and Fe-Zn-rich sulfide, and are characterized by the enrichment of base metal elements along with a sequence of Fe>Zn>Cu. Compared with sulfides from other hydrothermal fields on MAR, Zn concentrations of sulfides in the research area are significantly high, while Cu concentrations are relatively low. For all major, trace or rare-earth elements (REE), their concentrations and related characteristic parameters exhibit significant variations (up to one or two orders of magnitude), which indicates the sulfides from different hydrothermal vents or even a same station were formed at different stages of hydrothermal mineralization, and suggests the variations of chemical compositions of the hydrothermal fluid with respect to time. The hydrothermal temperatures of sulfides precipitation decreased gradually from station TVG10 (st.TVG10) to st.TVG12, and to st.TVG11, indicating that the precipitation of hydrothermal sulfides is subjected to conditions changed from high temperature to low temperature, and that the hydrothermal activity of study area was at the late stage of a general trend of evolution from strong to weak. The abnormally low concentrations of REE in sulfides and their similar chondrite-normalized REE patterns show that REEs in all sulfides were derived from a same source, but underwent different processes of migration or enrichment, or sulfides were formed at different stages of hydrothermal mineralization. The sulfides collected from the active hydrothermal vent were mainly attributed to precipitating directly from the hydrothermal fluid, while those collected from the extinct hydrothermal chimney might have already been altered by the seawater. Generally, ore-forming elements in the sulfides can be divided into three groups: Fe-based element group, Cu-based element group and Zn-based element group. The first group includes Fe, Mn, Cr, Mo, Sn, Rb and bio-enriching elements, such as P and Si, reflecting the similar characteristics to Fe in the study area. And the second group contains Cu, W, Co, Se, Te and Bi, suggesting the similar behavior with Cu. Moreover, the third group includes Zn, Hf, Hg, Cd, Ta, Ga, Pb, As, Ag, Ni and Sb, which indicates the geochemical characteristics of most dispersed trace elements controlled by Zn-bearing minerals to some extent.

Environmental controls on biomineralization and Fe-mound formation in a low-temperature hydrothermal system at the Jan Mayen Vent Fields

NASA Astrophysics Data System (ADS)

Johannessen, Karen C.; Vander Roost, Jan; Dahle, Håkon; Dundas, Siv H.; Pedersen, Rolf B.; Thorseth, Ingunn H.

2017-04-01

Diffuse low-temperature hydrothermal vents on the seafloor host neutrophilic microaerophilic Fe-oxidizing bacteria that utilize the Fe(II) supplied by hydrothermal fluids and produce intricate twisted and branching extracellular stalks. The growth behavior of Fe-oxidizing bacteria in strongly opposing gradients of Fe(II) and O2 have been thoroughly investigated in laboratory settings to assess whether extracellular stalks and aligned biomineralized fabrics may serve as biosignatures of Fe-oxidizing bacteria and indications of palaeo-redox conditions in the rock record. However, the processes controlling the growth of biogenic Fe-oxyhydroxide deposits in natural, modern hydrothermal systems are still not well constrained. In this study, we aimed to establish how variations in the texture of stratified hydrothermal Fe-oxyhydroxide deposits are linked to the physicochemical conditions of the hydrothermal environment. We conducted 16S rRNA gene analyses, microscopy and geochemical analyses of laminated siliceous Fe-mounds from the Jan Mayen Vent Fields at the Arctic Mid-Ocean Ridge. Chemical analyses of low- and high-temperature hydrothermal fluids were performed to characterize the hydrothermal system in which the Fe-deposits form. Our results reveal synchronous inter-laminar variations in texture and major and trace element geochemistry. The Fe-deposits are composed of alternating porous laminae of mineralized twisted stalks and branching tubes, Mn-rich horizons with abundant detrital sediment, domal internal cavities and thin P- and REE-enriched lamina characterized by networks of ≪1 μm wide fibers. Zetaproteobacteria constitute one third of the microbial community in the surface layer of actively forming mounds, indicating that microbial Fe-oxidation is contributing to mound accretion. We suggest that Mn-oxide precipitation and detrital sediment accumulation take place during periodically low hydrothermal fluid discharge conditions. The elevated concentrations of P and REE in distinct laminae suggest Fe-cycling and accumulation of diagenetic species at depth in the deposits during hydrothermal quiescence and co-precipitation of these species with Fe-oxyhydroxides at the mound surface with reinitiated hydrothermal discharge. The origin of the low-temperature hydrothermal source fluid and the Fe-deposits are evident by low LREE/HREE ratios and negative Eu-anomalies, which clearly differ from the LREE and Eu enrichment of nearby high-temperature white smoker venting fluids. Our study demonstrates that hydrothermal fluctuations exert the primary control on the formation of laminae and the activity of Fe-oxidizing bacteria in marine hydrothermal Fe-deposits and indicates that REE-patterns may be used to distinguish high-temperature plume fallout and biomineralized low-temperature Fe-deposits in the rock record.

Effect of growth time on the structure, morphology and optical properties of hydrothermally synthesized TiO2 nanorod thin films

NASA Astrophysics Data System (ADS)

Mohapatra, A. K.; Nayak, J.

2018-05-01

Titanium dioxide (TiO2) nanorod thin films were deposited on fluorine doped tin oxide coated glass substrates by a single step rapid hydrothermal process. The concentration of the precursor, the temperature of the reaction mixture were optimized in order to enhance the rate of deposition. Unlike the previously reported hydrothermal treatment for 24 - 48 h, the deposition of well aligned titanium dioxide nanorods was achieved in a short time such as 3 - 8 h. The crystal structure of the films were investigated by X-rays diffraction. The morphology of the nanorod films were studied with scanning electron microscopy. The optical properties were studied by photoluminescence spectroscopy.

Selected data fron continental scientific drilling core holes VC-1 and VC-2a, Valles Caldera, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musgrave, J.A.; Goff, F.; Shevenell, L.

1989-02-01

This report presents geochemical and isotopic data on rocks and water and wellbore geophysical data from the Continental Scientific Drilling Program core holes VC-1 and VC-2a, Valles Caldera, New Mexico. These core holes were drilled as a portion of a broader program that seeks to answer fundamental questions about magma, water/rock interactions, ore deposits, and volcanology. The data in this report will assist the interpretation of the hydrothermal system in the Jemez Mountains and will stimulate further research in magmatic processes, hydrothermal alteration, ore deposits, hydrology, structural geology, and hydrothermal solution chemistry. 37 refs., 36 figs., 28 tabs.

Hydrothermal Fabrication of WO3 Hierarchical Architectures: Structure, Growth and Response

PubMed Central

Wu, Chuan-Sheng

2015-01-01

Recently hierarchical architectures, consisting of two-dimensional (2D) nanostructures, are of great interest for potential applications in energy and environmental. Here, novel rose-like WO3 hierarchical architectures were successfully synthesized via a facile hydrothermal method. The as-prepared WO3 hierarchical architectures were in fact assembled by numerous nanosheets with an average thickness of ~30 nm. We found that the oxalic acid played a significant role in governing morphologies of WO3 during hydrothermal process. Based on comparative studies, a possible formation mechanism was also proposed in detail. Furthermore, gas-sensing measurement showed that the well-defined 3D WO3 hierarchical architectures exhibited the excellent gas sensing properties towards CO. PMID:28347062

Guide to the Revised Ground-Water Flow and Heat Transport Simulator: HYDROTHERM - Version 3

USGS Publications Warehouse

Kipp, Kenneth L.; Hsieh, Paul A.; Charlton, Scott R.

2008-01-01

The HYDROTHERM computer program simulates multi-phase ground-water flow and associated thermal energy transport in three dimensions. It can handle high fluid pressures, up to 1 ? 109 pascals (104 atmospheres), and high temperatures, up to 1,200 degrees Celsius. This report documents the release of Version 3, which includes various additions, modifications, and corrections that have been made to the original simulator. Primary changes to the simulator include: (1) the ability to simulate unconfined ground-water flow, (2) a precipitation-recharge boundary condition, (3) a seepage-surface boundary condition at the land surface, (4) the removal of the limitation that a specified-pressure boundary also have a specified temperature, (5) a new iterative solver for the linear equations based on a generalized minimum-residual method, (6) the ability to use time- or depth-dependent functions for permeability, (7) the conversion of the program code to Fortran 90 to employ dynamic allocation of arrays, and (8) the incorporation of a graphical user interface (GUI) for input and output. The graphical user interface has been developed for defining a simulation, running the HYDROTHERM simulator interactively, and displaying the results. The combination of the graphical user interface and the HYDROTHERM simulator forms the HYDROTHERM INTERACTIVE (HTI) program. HTI can be used for two-dimensional simulations only. New features in Version 3 of the HYDROTHERM simulator have been verified using four test problems. Three problems come from the published literature and one problem was simulated by another partially saturated flow and thermal transport simulator. The test problems include: transient partially saturated vertical infiltration, transient one-dimensional horizontal infiltration, two-dimensional steady-state drainage with a seepage surface, and two-dimensional drainage with coupled heat transport. An example application to a hypothetical stratovolcano system with unconfined ground-water flow is presented in detail. It illustrates the use of HTI with the combination precipitation-recharge and seepage-surface boundary condition, and functions as a tutorial example problem for the new user.

Extraction of valuable compounds from mangosteen pericarps by hydrothermal assisted sonication

NASA Astrophysics Data System (ADS)

Machmudah, Siti; Lestari, Sarah Duta; Shiddiqi, Qifni Yasa'Ash; Widiyastuti, Winardi, Sugeng; Wahyudiono, Kanda, Hideki; Goto, Motonobu

2015-12-01

Valuable compounds, such as xanthone and phenolic compounds, from mangosteen pericarps was extracted by hydrothermal treatment at temperatures of 120-160 °C and pressures of 5 MPa using batch and semi-batch extractor. This method is a simple and environmentally friendly extraction method requiring no chemicals other than water. Under these conditions, there is possibility for the formation of phenolic compounds from mangosteen pericarps from decomposition of bounds between lignin, cellulose, and hemicellulose via autohydrolysis. In order to increase the amount of extracted valuable compounds, sonication pre-treament was performed prior to the hydrothermal extraction process. 30 min of sonication pre-treatment could increase significantly the amount of xanthone and phenolic compounds mangosteen pericarps extraction. In batch-system, the xanthone recovery approach to 100 % at 160 °C with 30 min sonication pre-treatment for 150 min extraction time. Under semi-batch process, the total phenolic compounds in the extract was 217 mg/g sample at 160 °C with 30 min sonication pre-treatment for 150 min total extraction time. The results revealed that hydrothermal extraction assisted sonication pre-treatment is applicable method for the isolation of polyphenolic compounds from other types of biomass and may lead to an advanced plant biomass components extraction technology.

Hydrothermal alteration of deep fractured granite: Effects of dissolution and precipitation

NASA Astrophysics Data System (ADS)

Nishimoto, Shoji; Yoshida, Hidekazu

2010-03-01

This paper investigates the mineralogical effects of hydrothermal alteration at depth in fractures in granite. A fracture accompanied by an alteration halo and filled with clay was found at a depth of 200 m in a drill core through Toki granite, Gifu, central Japan. Microscopic observation, XRD, XRF, EPMA and SXAM investigations revealed that the microcrystalline clays consist of illite, quartz and pyrite and that the halo round the fracture can be subdivided into a phyllic zone adjacent to the fracture, surrounded by a propylitic zone in which Fe-phyllosilicates are present, and a distinctive outer alteration front characterized by plagioclase breakdown. The processes that result in these changes took place in three successive stages: 1) partial dissolution of plagioclase with partial chloritization of biotite; 2) biotite dissolution and precipitation of Fe-phyllosilicate in the dissolution pores; 3) dissolution of K-feldspar and Fe-phyllosilicate, and illite precipitation associated with development of microcracks. These hydrothermal alterations of the granite proceed mainly by a dissolution-precipitation process resulting from the infiltration of hydrothermal fluid along microcracks. Such infiltration causes locally high mobility of Al and increases the ratio of fluid to rock in the alteration halo. These results contribute to an understanding of how granitic rock becomes altered in orogenic fields such as the Japanese island arc.

Seismic and infrasonic source processes in volcanic fluid systems

NASA Astrophysics Data System (ADS)

Matoza, Robin S.

Volcanoes exhibit a spectacular diversity in fluid oscillation processes, which lead to distinct seismic and acoustic signals in the solid earth and atmosphere. Volcano seismic waveforms contain rich information on the geometry of fluid migration, resonance effects, and transient and sustained pressure oscillations resulting from unsteady flow through subsurface cracks, fissures and conduits. Volcanic sounds contain information on shallow fluid flow, resonance in near-surface cavities, and degassing dynamics into the atmosphere. Since volcanoes have large spatial scales, the vast majority of their radiated atmospheric acoustic energy is infrasonic (<20 Hz). This dissertation presents observations from joint broadband seismic and infrasound array deployments at Mount St. Helens (MSH, Washington State, USA), Tungurahua (Ecuador), and Kilauea Volcano (Hawaii, USA), each providing data for several years. These volcanoes represent a broad spectrum of eruption styles ranging from hawaiian to plinian in nature. The catalogue of recorded infrasonic signals includes continuous broadband and harmonic tremor from persistent degassing at basaltic lava vents and tubes at Pu'u O'o (Kilauea), thousands of repetitive impulsive signals associated with seismic longperiod (0.5-5 Hz) events and the dynamics of the shallow hydrothermal system at MSH, rockfall signals from the unstable dacite dome at MSH, energetic explosion blast waves and gliding infrasonic harmonic tremor at Tungurahua volcano, and large-amplitude and long-duration broadband signals associated with jetting during vulcanian, subplinian and plinian eruptions at MSH and Tungurahua. We develop models for a selection of these infrasonic signals. For infrasonic long-period (LP) events at MSH, we investigate seismic-acoustic coupling from various buried source configurations as a means to excite infrasound waves in the atmosphere. We find that linear elastic seismic-acoustic transmission from the ground to atmosphere is inadequate to explain the observations, and propose that the signals may result from sudden containment failure of a pressurized hydrothermal crack. For the broadband eruption tremor signals, we propose that the infrasonic signals represent a low-frequency form of jet noise, analogous to the noise from man-made jet engines, but operating with larger spatial scales and consequently longer time-scales. For the persistent hawaiian tremor signals, we propose that bubble cloud oscillation in the upper section of a roiling magma conduit and vortex dynamics in the shallow degassing region act as broadband and harmonic tremor sources. We also consider infrasound propagation effects in a dynamic atmosphere and discuss their effects on recorded signals. This dissertation demonstrates that combined seismic and infrasonic data provide complementary perspectives on eruptive activity.

Controls on Martian Hydrothermal Systems: Application to Valley Network and Magnetic Anomaly Formation

NASA Technical Reports Server (NTRS)

Harrison, Keith P.; Grimm, Robert E.

2002-01-01

Models of hydrothermal groundwater circulation can quantify limits to the role of hydrothermal activity in Martian crustal processes. We present here the results of numerical simulations of convection in a porous medium due to the presence of a hot intruded magma chamber. The parameter space includes magma chamber depth, volume, aspect ratio, and host rock permeability and porosity. A primary goal of the models is the computation of surface discharge. Discharge increases approximately linearly with chamber volume, decreases weakly with depth (at low geothermal gradients), and is maximized for equant-shaped chambers. Discharge increases linearly with permeability until limited by the energy available from the intrusion. Changes in the average porosity are balanced by changes in flow velocity and therefore have little effect. Water/rock ratios of approximately 0.1, obtained by other workers from models based on the mineralogy of the Shergotty meteorite, imply minimum permeabilities of 10(exp -16) sq m2 during hydrothermal alteration. If substantial vapor volumes are required for soil alteration, the permeability must exceed 10(exp -15) sq m. The principal application of our model is to test the viability of hydrothermal circulation as the primary process responsible for the broad spatial correlation of Martian valley networks with magnetic anomalies. For host rock permeabilities as low as 10(exp -17) sq m and intrusion volumes as low as 50 cu km, the total discharge due to intrusions building that part of the southern highlands crust associated with magnetic anomalies spans a comparable range as the inferred discharge from the overlying valley networks.

Microbial diversity and biogeochemistry of the Guaymas Basin deep-sea hydrothermal plume.

PubMed

Dick, Gregory J; Tebo, Bradley M

2010-05-01

Hydrothermal plumes are hot spots of microbial biogeochemistry in the deep ocean, yet little is known about the diversity or ecology of microorganisms inhabiting plumes. Recent biogeochemical evidence shows that Mn(II) oxidation in the Guaymas Basin (GB) hydrothermal plume is microbially mediated and suggests that the plume microbial community is distinct from deep-sea communities. Here we use a molecular approach to compare microbial diversity in the GB plume and in background deep seawater communities, and cultivation to identify Mn(II)-oxidizing bacteria from plumes and sediments. Despite dramatic differences in Mn(II) oxidation rates between plumes and background seawater, microbial diversity and membership were remarkably similar. All bacterial clone libraries were dominated by Gammaproteobacteria and archaeal clone libraries were dominated by Crenarchaeota. Two lineages, both phylogenetically related to methanotrophs and/or methylotrophs, were consistently over-represented in the plume. Eight Mn(II)-oxidizing bacteria were isolated, but none of these or previously identified Mn(II) oxidizers were abundant in clone libraries. Taken together with Mn(II) oxidation rates measured in laboratory cultures and in the field, these results suggest that Mn(II) oxidation in the GB hydrothermal plume is mediated by genome-level dynamics (gene content and/or expression) of microorganisms that are indigenous and abundant in the deep sea but have yet to be unidentified as Mn(II) oxidizers.

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.

Hydrothermal synthesis and afterglow luminescence properties of hollow SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} spheres for potential application in drug delivery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Pengfei; Zhang, Jiachi, E-mail: zhangjch@lzu.edu.cn; Qin, Qingsong

2014-02-01

Highlights: • We designed a novel afterglow labeling material SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} for the first time. • Hollow SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} spheres with afterglow were prepared by hydrothermal method. • Hollow SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} is a potential afterglow labeling medium for drug delivery. - Abstract: A novel afterglow labeling material SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} with hollow sphere shape and intense afterglow luminescence is prepared by hydrothermal method at 180 °C for the first time. The morphology and the sphere growth process of this material are investigated by scanning electron microscopy in detail. The afterglow measurement shows thatmore » this hydrothermal obtained material exhibits obvious red afterglow luminescence (550–700 nm) of Sm{sup 3+} which can last for 542 s (0.32 mcd/m{sup 2}). The depth of traps in this hydrothermal obtained material is calculated to be as shallow as 0.58 eV. The results demonstrate that although it is necessary to further improve the afterglow performance of the hydrothermal derived hollow SnO{sub 2}:Sm{sup 3+},Zr{sup 4+} spheres, it still can be regarded as a potential afterglow labeling medium for drug delivery.« less

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.

Mathematical Models of Seafloor Hydrothermal Systems Driven by Serpentinization of Peridotite

NASA Astrophysics Data System (ADS)

Lowell, R. P.; Rona, P. A.; Germanovich, L. N.

2001-12-01

Most seafloor hydrothermal systems are driven by heat transfer from subsurface magma bodies. At slow spreading ridges of the Atlantic and Indian oceans, however, magma supply is low; and tectonic activity brings mantle rocks to shallow depths in the crust. Then, the heat of formation released upon serpentinization of peridotite provides the energy source for hydrothermal circulation. This latter class of system has been relatively unstudied, but recent discoveries of peridotite-hosted hydrothermal systems along the Mid-Atlantic Ridge suggest that such systems may play an important role in geochemical cycling and biogeochemical processes. The likelihood that peridotite-hosted hydrothermal systems was more prevalent during the Archean further suggests that such systems may have played a role in the origin of life. We present the first mathematical models of seafloor hydrothermal systems driven by heat released upon serpentinization of peridotite. We assume seawater circulates through a major crack network in the host-peridotite and that cooling of the host-rock leads to the formation of microcracks through which the fluid infiltrates. Reaction of the fluid in microcracks with the host rock results in serpentinization and the heat released upon serpentinization is transported to the seafloor by the fluid circulating in the main crack network. The temperature and heat output of the resulting hydrothermal system is a function of the main network permeability and the rate at which the serpentinization reaction proceeds via diffusion and propagation of the microcracks. Although the temperature of such a system can be quite variable, vent temperatures between 10° C and 100° C are likely for typical crustal parameters.

Formation and modification of chromitites in the mantle

NASA Astrophysics Data System (ADS)

Arai, Shoji; Miura, Makoto

2016-11-01

Podiform chromitites have long supplied us with unrivaled information on various mantle processes, including the peridotite-magma reaction, deep-seated magmatic evolution, and mantle dynamics. The recent discovery of ultrahigh-pressure (UHP) chromitites not only sheds light on a different aspect of podiform chromitites, but also changes our understanding of the whole picture of podiform chromitite genesis. In addition, new evidence was recently presented for hydrothermal modification/formation chromite/chromitite in the mantle, which is a classical but innovative issue. In this context, we present here an urgently needed comprehensive review of podiform chromitites in the upper mantle. Wall-rock control on podiform chromitite genesis demonstrates that the peridotite-magma reaction at the upper mantle condition is an indispensable process. We may need a large system in the mantle, far larger than the size of outcrops or mining areas, to fulfill the Cr budget requirement for podiform chromitite genesis. The peridotite-magma reaction over a large area may form a melt enriched with Na and other incompatible elements, which mixes with a less evolved magma supplied from the depth to create chromite-oversaturated magma. The incompatible-element-rich magma trapped by the chromite mainly precipitates pargasite and aspidolite (Na analogue of phlogopite), which are stable under upper mantle conditions. Moderately depleted harzburgites, which contain chromite with a moderate Cr# (0.4-0.6) and a small amount of clinopyroxene, are the best reactants for the chromitite-forming reaction, and are the best hosts for podiform chromitites. Arc-type chromitites are dominant in ophiolites, but some are of the mid-ocean ridge type; chromitites may be common beneath the ocean floor, although it has not yet been explored for chromitite. The low-pressure (upper mantle) igneous chromitites were conveyed through mantle convection or subduction down to the mantle transition zone to form ultrahigh-pressure chromitites. Some of these reappear at the shallower mantle, and can coexist with newly formed low-pressure igneous chromitites. High-temperature hydrothermal fluids can dissolve and precipitate chromite, and hydrothermal chromitites (chromitites precipitated from aqueous fluids) are possibly formed within the mantle where the circulation of hydrous fluid is available, e.g., at the mantle wedge.

Microevolutionary dynamics in Methanothermococcus populations from deep-sea hydrothermal vents in the Mid-Cayman Rise

NASA Astrophysics Data System (ADS)

Hoffert, M.; Anderson, R. E.; Stepanauskas, R.; Huber, J. A.

2017-12-01

Deep-sea hydrothermal vents sustain diverse communities of microorganisms. The effects of geochemical and biological interactions on the process of evolution in these ecosystems remains poorly understood because the majority of subsurface microorganisms remain uncultivated. By examining metagenomic samples from hydrothermal fluids and mapping the samples to closely-related genomes found in vent sites, we can better understand how the process of evolution is affected by the geochemical and environmental context in deep-sea vents. The Mid-Cayman Rise is a spreading ridge that hosts both mafic-influenced and ultramafic-influenced vent fields. Previous research on metagenomic samples from sites in the Mid-Cayman Rise has shown that these vents contain metabolically and taxonomically diverse microbial communities. Here, we investigate five single cell amplified Methanothermococcus genomes (SAGs) to investigate patterns in pangenomic variation and molecular evolution in these methanogens. Mappings of metagenomic reads from 15 sample sites to the SAGs reveal substantial variation in Methanothermococcus population abundance, nucleotide variability and selection pressure among the 15 geochemically distinct sample sites. Within each sample site, we observed distinct patterns of single nucleotide variant (SNV) accumulation and selection pressure within the SAG populations. Closely related genomes showed similar patterns of SNV accumulation. Analysis of open reading frames (ORFs) from the SAGs indicated that homologous genes accumulated variation at the same rate. For example, a genomic island for Nif genes was identified in three of the five genomes with significantly elevated SNV counts. dN/dS analyses revealed evidence for frequency-dependent selection, in which genes unique to individual SAGs displayed elevated diversifying selection relative to other genes. These results indicate that different strains of Methanothermococcus outcompete others in specific environmental settings, and that these fitness advantages may result from variation in the pangenome, as revealed by dN/dS and SNV analyses. By examining variation and the scale of nucleotide and genes, we aim to gain insight into the roles of genetic diversity and environmental selection on microbial evolution in these ecosystems.

Numerical models of caldera deformation: Effects of multiphase and multicomponent hydrothermal fluid flow

USGS Publications Warehouse

Hutnak, M.; Hurwitz, S.; Ingebritsen, S.E.; Hsieh, P.A.

2009-01-01

Ground surface displacement (GSD) in large calderas is often interpreted as resulting from magma intrusion at depth. Recent advances in geodetic measurements of GSD, notably interferometric synthetic aperture radar, reveal complex and multifaceted deformation patterns that often require complex source models to explain the observed GSD. Although hydrothermal fluids have been discussed as a possible deformation agent, very few quantitative studies addressing the effects of multiphase flow on crustal mechanics have been attempted. Recent increases in the power and availability of computing resources allow robust quantitative assessment of the complex time-variant thermal interplay between aqueous fluid flow and crustal deformation. We carry out numerical simulations of multiphase (liquid-gas), multicomponent (H 2O-CO2) hydrothermal fluid flow and poroelastic deformation using a range of realistic physical parameters and processes. Hydrothermal fluid injection, circulation, and gas formation can generate complex, temporally and spatially varying patterns of GSD, with deformation rates, magnitudes, and geometries (including subsidence) similar to those observed in several large calderas. The potential for both rapid and gradual deformation resulting from magma-derived fluids suggests that hydrothermal fluid circulation may help explain deformation episodes at calderas that have not culminated in magmatic eruption.

Assessment of hydrothermal carbonization and coupling washing with torrefaction of bamboo sawdust for biofuels production.

PubMed

Zhang, Shuping; Su, Yinhai; Xu, Dan; Zhu, Shuguang; Zhang, Houlei; Liu, Xinzhi

2018-06-01

Two kinds of biofuels were produced and compared from hydrothermal carbonization (HTC) and coupling washing with torrefaction (CWT) processes of bamboo sawdust in this study. The mass and energy yields, mass energy density, fuel properties, structural characterizations, combustion behavior and ash behavior during combustion process were investigated. Significant increases in the carbon contents resulted in the improvement of mass energy density and fuel properties of biofuels obtained. Both HTC and CWT improved the safety of the biofuels during the process of handling, storing and transportation. The ash-related issues of the biofuels were significantly mitigated and combustion behavior was remarkably improved after HTC and CWT processes of bamboo sawdust. In general, both HTC and CWT processes are suitable to produce biofuels with high fuel quality from bamboo sawdust. Copyright © 2018 Elsevier Ltd. All rights reserved.

Heat flow bounds over the Cascadia margin derived from bottom simulating reflectors and implications for thermal models of subduction

NASA Astrophysics Data System (ADS)

Phrampus, Benjamin J.; Harris, Robert N.; Tréhu, Anne M.

2017-09-01

Understanding the thermal structure of the Cascadia subduction zone is important for understanding megathrust earthquake processes and seismogenic potential. Currently our understanding of the thermal structure of Cascadia is limited by a lack of high spatial resolution heat flow data and by poor understanding of thermal processes such as hydrothermal fluid circulation in the subducting basement, sediment thickening and dewatering, and frictional heat generation on the plate boundary. Here, using a data set of publically available seismic lines combined with new interpretations of bottom simulating reflector (BSR) distributions, we derive heat flow estimates across the Cascadia margin. Thermal models that account for hydrothermal circulation predict BSR-derived heat flow bounds better than purely conductive models, but still over-predict surface heat flows. We show that when the thermal effects of in-situ sedimentation and of sediment thickening and dewatering due to accretion are included, models with hydrothermal circulation become consistent with our BSR-derived heat flow bounds.

Techno-economic feasibility and life cycle assessment of dairy effluent to renewable diesel via hydrothermal liquefaction.

PubMed

Summers, Hailey M; Ledbetter, Rhesa N; McCurdy, Alex T; Morgan, Michael R; Seefeldt, Lance C; Jena, Umakanta; Hoekman, S Kent; Quinn, Jason C

2015-11-01

The economic feasibility and environmental impact is investigated for the conversion of agricultural waste, delactosed whey permeate, through yeast fermentation to a renewable diesel via hydrothermal liquefaction. Process feasibility was demonstrated at laboratory-scale with data leveraged to validate systems models used to perform industrial-scale economic and environmental impact analyses. Results show a minimum fuel selling price of $4.78 per gallon of renewable diesel, a net energy ratio of 0.81, and greenhouse gas emissions of 30.0g-CO2-eqMJ(-1). High production costs and greenhouse gas emissions can be attributed to operational temperatures and durations of both fermentation and hydrothermal liquefaction. However, high lipid yields of the yeast counter these operational demands, resulting in a favorable net energy ratio. Results are presented on the optimization of the process based on economy of scale and a sensitivity analysis highlights improvements in conversion efficiency, yeast biomass productivity and hydrotreating efficiency can dramatically improve commercial feasibility. Copyright © 2015 Elsevier Ltd. All rights reserved.

"Fabrication of arbitrarily shaped carbonate apatite foam based on the interlocking process of dicalcium hydrogen phosphate dihydrate".

PubMed

Sugiura, Yuki; Tsuru, Kanji; Ishikawa, Kunio

2017-08-01

Carbonate apatite (CO 3 Ap) foam with an interconnected porous structure is highly attractive as a scaffold for bone replacement. In this study, arbitrarily shaped CO 3 Ap foam was formed from α-tricalcium phosphate (α-TCP) foam granules via a two-step process involving treatment with acidic calcium phosphate solution followed by hydrothermal treatment with NaHCO 3 . The treatment with acidic calcium phosphate solution, which is key to fabricating arbitrarily shaped CO 3 Ap foam, enables dicalcium hydrogen phosphate dihydrate (DCPD) crystals to form on the α-TCP foam granules. The generated DCPD crystals cause the α-TCP granules to interlock with each other, inducing an α-TCP/DCPD foam. The interlocking structure containing DCPD crystals can survive hydrothermal treatment with NaHCO 3 . The arbitrarily shaped CO 3 Ap foam was fabricated from the α-TCP/DCPD foam via hydrothermal treatment at 200 °C for 24 h in the presence of a large amount of NaHCO 3 .

Hydrothermal carbonization for the preparation of hydrochars from glucose, cellulose, chitin, chitosan and wood chips via low-temperature and their characterization.

PubMed

Simsir, Hamza; Eltugral, Nurettin; Karagoz, Selhan

2017-12-01

In this work, the hydrothermal carbonization of glucose, cellulose, chitin, chitosan and wood chips at 200°C at processing times between 6 and 48h was studied. The carbonization degree of wood chips, cellulose and chitosan obviously increases as function of time. The heating value of glucose increases to 88% upon carbonization for 48h, while it is only 5% for chitin. It is calculated to be between 44 and 73% for wood chips, chitosan and cellulose. Glucose yielded complete formation of spherical hydrochar structures at a shorter processing time, as low as 12h. However, carbon spheres with narrow size (∼560nm) distribution were obtained upon 48h of residence time. Cellulose and wood chips yielded a similar morphology with an irregular size distribution. Chitin seemed not to undergo hydrothermal carbonization, whereas densely aggregated spheres of a uniform size around 42nm were obtained from chitosan after 18h. Copyright © 2017 Elsevier Ltd. All rights reserved.

Rheological and stability aspects of dry and hydrothermally heat treated aleurone-rich wheat milling fraction.

PubMed

Bucsella, Blanka; Takács, Ágnes; von Reding, Walter; Schwendener, Urs; Kálmán, Franka; Tömösközi, Sándor

2017-04-01

Novel aleurone-rich wheat milling fraction developed and produced on industry scale is investigated. The special composition of the novel flour with high protein, dietary fiber and fat content results in a unique combination of the mixing and viscosity properties. Due to the high lipid concentration, the fraction is exposed to fast rancidity. Dry heat (100°C for 12min) and hydrothermal treatment processes (96°C for 6min with 0-20 L/h steam) were applied on the aleurone-rich flour to modify the technological properties. The chemical, structural changes; the extractability of protein, carbohydrate and phenolic components and the rheological characteristics of the flours were evaluated. The dry treated flour decreased protein and carbohydrate extractability, shortened dough development time, reduced gel strength and enhanced the gelling ability. Hydrothermal treatment caused changes in the phenolic content improved the dough stability and -resistance. Heat treatment processes were able to extend the stability of the flour. Copyright © 2016 Elsevier Ltd. All rights reserved.

State Resolved Thermal Hydrothermal Collision Dynamics of Atmospheric Species

DTIC Science & Technology

2006-09-01

ABSTRACT 18 . NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) Standard Form 298 (Rev. 8/98) Prescnbed by ANSI...vJ » -, 22 11 ?n ■ 290(30)K \\ 1 , 1 1 2000 Erot (cm1) 3000 4000 liquid surface in vacuum, exploiting sub

PROCEEDINGS OF THE WORKSHOP ON SAMPLING GEOTHERMAL EFFLUENTS (2ND) HELD AT LAS VEGAS, NEVADA ON FEBRUARY 15-17, 1977

EPA Science Inventory

A partial listing of contents includes: The use of gas sampling bags for the collection and storage of hydrothermal gases; Heavy metal emissions from geothermal power plants; The dynamic measurement of ambient airborne gases near geothermal areas; Analysis of radon in geothermal ...

Assessing the Role of Seafloor Weathering in Global Geochemical Cycling

NASA Astrophysics Data System (ADS)

Farahat, N. X.; Abbot, D. S.; Archer, D. E.

2015-12-01

Low-temperature alteration of the basaltic upper oceanic crust, known as seafloor weathering, has been proposed as a mechanism for long-term climate regulation similar to the continental climate-weathering negative feedback. Despite this potentially far-reaching impact of seafloor weathering on habitable planet evolution, existing modeling frameworks do not include the full scope of alteration reactions or recent findings of convective flow dynamics. We present a coupled fluid dynamic and geochemical numerical model of low-temperature, off-axis hydrothermal activity. This model is designed to explore the the seafloor weathering flux of carbon to the oceanic crust and its responsiveness to climate fluctuations. The model's ability to reproduce the seafloor weathering environment is evaluated by constructing numerical simulations for comparison with two low-temperature hydrothermal systems: A transect east of the Juan de Fuca Ridge and the southern Costa Rica Rift flank. We explore the sensitivity of carbon uptake by seafloor weathering on climate and geology by varying deep ocean temperature, seawater dissolved inorganic carbon, continental weathering inputs, and basaltic host rock in a suite of numerical experiments.

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments.

PubMed

Daly, Paul; van Munster, Jolanda M; Blythe, Martin J; Ibbett, Roger; Kokolski, Matt; Gaddipati, Sanyasi; Lindquist, Erika; Singan, Vasanth R; Barry, Kerrie W; Lipzen, Anna; Ngan, Chew Yee; Petzold, Christopher J; Chan, Leanne Jade G; Pullan, Steven T; Delmas, Stéphane; Waldron, Paul R; Grigoriev, Igor V; Tucker, Gregory A; Simmons, Blake A; Archer, David B

2017-01-01

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retaining more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.

Synthesis of high intrinsic loss power aqueous ferrofluids of iron oxide nanoparticles by citric acid-assisted hydrothermal-reduction route

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behdadfar, Behshid, E-mail: bbehdadfar@ma.iut.ac.ir; Kermanpur, Ahmad; Sadeghi-Aliabadi, Hojjat

Monodispersed aqueous ferrofluids of iron oxide nanoparticle were synthesized by hydrothermal-reduction route. They were characterized by X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning and transmission electron microscopy and dynamic light scattering. The results showed that certain concentrations of citric acid (CA) are required to obtain only magnetic iron oxides with mean particle sizes around 8 nm. CA acts as a modulator and reducing agent in iron oxide formation which controls nanoparticle size. The XRD, magnetic and heating measurements showed that the temperature and time of hydrothermal reaction can affect the magnetic properties of obtained ferrofluids. The synthesized ferrofluids weremore » stable at pH 7. Their mean hydrodynamic size was around 80 nm with polydispersity index (PDI) of 0.158. The calculated intrinsic loss power (ILP) was 9.4 nHm{sup 2}/kg. So this clean and cheap route is an efficient way to synthesize high ILP aqueous ferrofluids applicable in magnetic hyperthermia. - Graphical abstract: Monodispersed aqueous ferrofluids of iron oxide nanoparticles were synthesized by hydrothermal-reduction method with citric acid as reductant which is an efficient way to synthesize aqueous ferrofluids applicable in magnetic hyperthermia. Highlights: Black-Right-Pointing-Pointer Aqueous iron oxide ferrofluids were synthesized by hydrothermal-reduction route. Black-Right-Pointing-Pointer Citric acid acted as reducing agent and surfactant in the route. Black-Right-Pointing-Pointer This is a facile, low energy and environmental friendly route. Black-Right-Pointing-Pointer The aqueous iron oxide ferrofluids were monodispersed and stable at pH of 7. Black-Right-Pointing-Pointer The calculated intrinsic loss power of the synthesized ferrofluids was very high.« less

Experimental Investigation of Organic Synthesis in Hydrothermal Environments

NASA Technical Reports Server (NTRS)

Shock, Everett L.

1998-01-01

Seafloor hydrothermal systems may be the most likely locations on the early Earth for the emergence of life. Because of the disequilibrium inherent in such dynamic, mixing environments, abundant chemical energy would have been available for formation of the building blocks of life. In addition, theoretical studies suggest that organic compounds in these conditions would reach metastable states, due to kinetic barriers to the formation of stable equilibrium products (CO2 and methane). The speciation of organic carbon in metastable states is highly dependent on the oxidation state, pH, temperature, pressure and bulk composition of the system. The goal of our research is to investigate the effects of a number external variables on the formation, transformation, and stability of organic compounds at hydrothermal conditions. We have begun experimental work to attempt to control the oxidation state of simulated hydrothermal systems by using buffers composed of mineral powders and gas mixtures. We are also beginning to test the stability of organic compounds under these conditions. The experiments are being performed using the hydrothermal bomb apparatus at the U.S. Geological Survey in Menlo Park, CA and the supercritical water oxidizer (SCWO) at NASA Ames Research Center in Moffet Field, CA. The amino acids decomposed rapidly. Even after the approximately 15 minutes between addition of the amino acids and the first sampling, no amino acids were detected in the PPM system by GC- MS, while in the FeFeO system the amino acids were present at a level of less than 50% of original. Carboxylic acids, ammonia, and CO2 were the main products, along with some unidentified compounds. The ratios of carboxylic acids and concentrations of other products seem to have remained stable during the experiments, consistent with observations of other metastable systems and theoretical predictions.

Zeolite Coating System for Corrosion Control to Eliminate Hexavalent Chromium from DoD Applications

DTIC Science & Technology

2009-08-01

Beving D.; Munoz R.; Yushan Y. 2005, Hydrothermal Synthesis and Corrosion Resistance of Vanadium ZSM-5 Films, The American Institute of Chemical...Engineers National Meeting, October 30 - November 4, Cincinnati, Ohio. 8) Mao Y.; Beving D.; Munoz R.; Yushan Y. 2005, Hydrothermal Synthesis of...directly at the solid-liquid interface from a synthesis solution during the coating formation process (Figure 2-4)12. The synthesis solution used is a

Formation mechanism of rectangular-ambulatory-plane TiO2 plates: an insight into the role of hydrofluoric acid.

PubMed

Zou, Yajun; Gao, Ge; Wang, Zhenyu; Shi, Jian-Wen; Wang, Hongkang; Ma, Dandan; Fan, Zhaoyang; Chen, Xin; Wang, Zeyan; Niu, Chunming

2018-06-13

A novel rectangular-ambulatory-plane TiO2 plate with exposed {001} facets was developed for the first time via a facile microwave-assisted hydrothermal approach in the presence of HF solution. Solid evidence demonstrated that HF plays dual roles in the hydrothermal process, both as a stabilizer for the {001} facet growth and as an etching reagent selectively destroying the {001} facets.

Characterization of lignin during oxidative and hydrothermal pre-treatment processes of wheat straw and corn stover.

PubMed

Kaparaju, Prasad; Felby, Claus

2010-05-01

The objective of the study was to characterize and map changes in lignin during hydrothermal and wet explosion pre-treatments of wheat straw and corn stover. Chemical composition, microscopic (atomic force microscopy and scanning electron microscopy) and spectroscopic (attenuated total reflectance Fourier transform infrared spectroscopy, ATR-FTIR) analyses were performed. Results showed that both pre-treatments improved the cellulose and lignin content with substantial removal of hemicellulose in the pre-treated biomasses. These values were slightly higher for hydrothermal compared to wet explosion pre-treatment. ATR-FTIR analyses also confirmed these results. Microscopic analysis showed that pre-treatments affected the biomass by partial difibration. Lignin deposition on the surface of the hydrothermally pre-treated fibre was very distinct while severe loss of fibril integrity was noticed with wet exploded fibre. The present study thus revealed that the lignin cannot be removed by the studied pre-treatments. However, both pre-treatments improved the accessibility of the biomass towards enzymatic hydrolysis. Copyright 2009 Elsevier Ltd. All rights reserved.

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

An Anion-Induced Hydrothermal Oriented-Explosive Strategy for the Synthesis of Porous Upconversion Nanocrystals

PubMed Central

Qiu, Peiyu; Sun, Rongjin; Gao, Guo; Zhang, Chunlei; Chen, Bin; Yan, Naishun; Yin, Ting; Liu, Yanlei; Zhang, Jingjing; Yang, Yao; Cui, Daxiang

2015-01-01

Rare-earth (RE)-doped upconversion nanocrystals (UCNCs) are deemed as the promising candidates of luminescent nanoprobe for biological imaging and labeling. A number of methods have been used for the fabrication of UCNCs, but their assembly into porous architectures with desired size, shape and crystallographic phase remains a long-term challenging task. Here we report a facile, anion-induced hydrothermal oriented-explosive method to simultaneously control size, shape and phase of porous UCNCs. Our results confirmed the anion-induced hydrothermal oriented-explosion porous structure, size and phase transition for the cubic/hexagonal phase of NaLuF4 and NaGdF4 nanocrystals with various sizes and shapes. This general method is very important not only for successfully preparing lanthanide doped porous UCNCs, but also for clarifying the formation process of porous UCNCs in the hydrothermal system. The synthesized UCNCs were used for in vitro and in vivo CT imaging, and could be acted as the potential CT contrast agents. PMID:25767613

Hydrothermal pretreatment enhanced enzymatic hydrolysis and glucose production from oil palm biomass.

PubMed

Zakaria, Mohd Rafein; Hirata, Satoshi; Hassan, Mohd Ali

2015-01-01

The present works investigate hydrothermal pretreatment of oil palm empty fruit bunch and oil palm frond fiber in a batch tube reactor system with temperature and time range from 170 to 250°C and 10 to 20min, respectively. The behavior of soluble sugars, acids, furans, and phenols dramatically changed over treatment severities as determined by HPLC. The cellulose-rich treated solids were analyzed by SEM, WAXD, and BET surface area. Enzymatic hydrolysis was performed from both pretreated slurries and washed solid, and data obtained suggested that tannic acid derived from lignin degradation was a potential cellulase inhibitor. Both partial removal of hemicellulose and migration of lignin during hydrothermal pretreatment caused structural changes on the cellulose-hemicellulose-lignin matrix, resulting in the opening and expansion of specific surface area and pore volume. The current results provided important factors that maximize conversion of cellulose to glucose from oil palm biomass by hydrothermal process. Copyright © 2014 Elsevier Ltd. All rights reserved.

Belite cement clinker from coal fly ash of high Ca content. Optimization of synthesis parameters.

PubMed

Guerrero, A; Goñi, S; Campillo, I; Moragues, A

2004-06-01

The optimization of parameters of synthesis of belite cement clinker from coal fly ash of high Ca content is presented in this paper. The synthesis process is based on the hydrothermal-calcination-route of the fly ash without extra additions. The hydrothermal treatment was carried out in demineralized water and a 1 M NaOH solution for 4 h at the temperatures of 100 degrees C, 150 degrees C, and 200 degrees C. The precursors obtained during the hydrothermal treatmentwere heated at temperatures of 700 degrees C, 800 degrees C, 900 degrees C, and 1000 degrees C. The changes of fly ash composition after the different treatments were characterized by X-ray diffraction (XRD), FT infrared (FTIR) spectroscopy, surface area (BET-N2), and thermal analyses. From the results obtained we concluded that the optimum temperature of the hydrothermal treatment was 200 degrees C, and the optimum temperature for obtaining the belite cement clinker was 800 degrees C.

Massive collapse of volcano edifices triggered by hydrothermal pressurization

USGS Publications Warehouse

Reid, M.E.

2004-01-01

Catastrophic collapse of steep volcano flanks threatens lives at stratovolcanoes around the world. Although destabilizing shallow intrusion of magma into the edifice accompanies some collapses (e.g., Mount St. Helens), others have occurred without eruption of juvenile magmatic materials (e.g., Bandai). These latter collapses can be difficult to anticipate. Historic collapses without magmatic eruption are associated with shallow hydrothermal groundwater systems at the time of collapse. Through the use of numerical models of heat and groundwater flow, I evaluate the efficacy of hydrothermally driven collapse. Heating from remote magma intrusion at depth can generate temporarily elevated pore-fluid pressures that propagate upward into an edifice. Effective-stress deformation modeling shows that these pressures are capable of destabilizing the core of an edifice, resulting in massive, deep-seated collapse. Far-field pressurization only occurs with specific rock hydraulic properties; however, data from numerous hydrothermal systems illustrate that this process can transpire in realistic settings. ?? 2004 Geological Society of America.

The energetics of organic synthesis inside and outside the cell

PubMed Central

Amend, Jan P.; LaRowe, Douglas E.; McCollom, Thomas M.; Shock, Everett L.

2013-01-01

Thermodynamic modelling of organic synthesis has largely been focused on deep-sea hydrothermal systems. When seawater mixes with hydrothermal fluids, redox gradients are established that serve as potential energy sources for the formation of organic compounds and biomolecules from inorganic starting materials. This energetic drive, which varies substantially depending on the type of host rock, is present and available both for abiotic (outside the cell) and biotic (inside the cell) processes. Here, we review and interpret a library of theoretical studies that target organic synthesis energetics. The biogeochemical scenarios evaluated include those in present-day hydrothermal systems and in putative early Earth environments. It is consistently and repeatedly shown in these studies that the formation of relatively simple organic compounds and biomolecules can be energy-yielding (exergonic) at conditions that occur in hydrothermal systems. Expanding on our ability to calculate biomass synthesis energetics, we also present here a new approach for estimating the energetics of polymerization reactions, specifically those associated with polypeptide formation from the requisite amino acids. PMID:23754809

Microstructure and magnetic properties of MFe2O4 (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

NASA Astrophysics Data System (ADS)

Wang, Wei; Ding, Zui; Zhao, Xiruo; Wu, Sizhu; Li, Feng; Yue, Ming; Liu, J. Ping

2015-05-01

Three kinds of spinel ferrite nanocrystals, MFe2O4 (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH4) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modes at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (Ms). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.

[Study on hydrothermal stability of the collagen].

PubMed

Wang, Yajuan; Chen, Hui; Shan, Zhihua

2009-02-01

The low hydrothermal stability of the raw collagen restricts its usage. To improve the hydrothermal stability of collagen, two kinds of materials with weak astringency were used by experts. The research proved that the synergistic effect was formed during the process. In this study, by using UV, FT-IR, 13CNMR spectra and elemental analysis on the salicylic acid and metal-salicylic complexes, we could get the structural formula of every compound. And then, the hide powder was treated with the compounds. At last, the treated hide powder was tested by DSC. It could be presumed that the Rigid Matrix formed between the collagen doses can increase the hydrothermal stability of raw collagen, The result indicated that salicylic-chrome with large stable constant was better than others in improving the heat resistance of raw collagen, and the denaturalization temperature of hide powder treated with salicylic-chrome was 146.7 degrees C. Salicylic-aluminum was in the second place, the relevant temperature being 145.7 degrees C.

CONTRIBUTION TO THE GEOCHEMISTRY OF TANTALUM AND NIOBIUM IN THE HYDROTHERMAL-PNEUMATHOLYTIC PROCESS (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beus, A.A.; Sitnin, A.A.

1961-01-01

S>Data obtained as a result of geochemical investigations show that tantalum and niobium are typical elements of high-temperature postmagmatic processes (early albitization, greysening) connected with granites. The separation of tantalum and niobium in the hydrothermal-pneumatholytic process (greysening stage), which leads to the concentration of tantalum in albitized and greysenized granites (40 to 100 times compared to the average content in granites) is connected with the different mobility and stability of their acido- complex compounds (in particular fluor- and oxyfluorcomplexes), the existence of which in greysening solutions is suggested. A natural analogy in the behavior of both elements in the processesmore » of postmagmatic metasomatose in granites and granitic pegmatites is suggested. (tr-auth)« less

[Chemical characteristics and uses of instant corn flour II].

PubMed

Martínez, F; el-Dahs, A A

1993-12-01

The hydrothermal process using corn grits soaked in water at room temperature (28-30 degrees C) for 5 hours and steaming for 1 minute at 118 degrees C did not affect the proximal composition of the corn flour. However, the amino acid content was reduced approximately 18% (specially lysine and tryptophan). Vitamin and pigment contents were few affected. The characteristics of color and shelf life of corn flour were improved with the hydrothermal process. Tortillas prepared with instant corn flour showed better color and texture in comparison to the tortillas prepared by the conventional process. Polentas prepared with instant corn flour with 30 seconds of mixing showed better characteristics of flavor, odor, texture and required less preparation time than commercial polentas.

Silver Vanadium Phosphorous Oxide, Ag(2)VO(2)PO(4): Chimie Douce Preparation and Resulting Lithium Cell Electrochemistry.

PubMed

Kim, Young Jin; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

2011-08-15

Recently, we have shown silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4), SVPO) to be a promising cathode material for lithium based batteries. Whereas the first reported preparation of SVPO employed an elevated pressure, hydrothermal approach, we report herein a novel ambient pressure synthesis method to prepare SVPO, where our chimie douce preparation is readily scalable and provides material with a smaller, more consistent particle size and higher surface area relative to SVPO prepared via the hydrothermal method. Lithium electrochemical cells utilizing SVPO cathodes made by our new process show improved power capability under constant current and pulse conditions over cells containing cathode from SVPO prepared via the hydrothermal method.

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.

Photosynthetic microbial mats in the 3,416-Myr-old ocean.

PubMed

Tice, Michael M; Lowe, Donald R

2004-09-30

Recent re-evaluations of the geological record of the earliest life on Earth have led to the suggestion that some of the oldest putative microfossils and carbonaceous matter were formed through abiotic hydrothermal processes. Similarly, many early Archaean (more than 3,400-Myr-old) cherts have been reinterpreted as hydrothermal deposits rather than products of normal marine sedimentary processes. Here we present the results of a field, petrographic and geochemical study testing these hypotheses for the 3,416-Myr-old Buck Reef Chert, South Africa. From sedimentary structures and distributions of sand and mud, we infer that deposition occurred in normal open shallow to deep marine environments. The siderite enrichment that we observe in deep-water sediments is consistent with a stratified early ocean. We show that most carbonaceous matter was formed by photosynthetic mats within the euphotic zone and distributed as detrital matter by waves and currents to surrounding environments. We find no evidence that hydrothermal processes had any direct role in the deposition of either the carbonaceous matter or the enclosing sediments. Instead, we conclude that photosynthetic organisms had evolved and were living in a stratified ocean supersaturated in dissolved silica 3,416 Myr ago.

Photosynthetic microbial mats in the 3,416-Myr-old ocean

NASA Astrophysics Data System (ADS)

Tice, Michael M.; Lowe, Donald R.

2004-09-01

Recent re-evaluations of the geological record of the earliest life on Earth have led to the suggestion that some of the oldest putative microfossils and carbonaceous matter were formed through abiotic hydrothermal processes. Similarly, many early Archaean (more than 3,400-Myr-old) cherts have been reinterpreted as hydrothermal deposits rather than products of normal marine sedimentary processes. Here we present the results of a field, petrographic and geochemical study testing these hypotheses for the 3,416-Myr-old Buck Reef Chert, South Africa. From sedimentary structures and distributions of sand and mud, we infer that deposition occurred in normal open shallow to deep marine environments. The siderite enrichment that we observe in deep-water sediments is consistent with a stratified early ocean. We show that most carbonaceous matter was formed by photosynthetic mats within the euphotic zone and distributed as detrital matter by waves and currents to surrounding environments. We find no evidence that hydrothermal processes had any direct role in the deposition of either the carbonaceous matter or the enclosing sediments. Instead, we conclude that photosynthetic organisms had evolved and were living in a stratified ocean supersaturated in dissolved silica 3,416Myr ago.

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.

Electron microscopy studies of the morphological evolution in hydrothermally derived lead titanate

NASA Astrophysics Data System (ADS)

Ye, Zhiyuan

Hydrothermal processing is a promising technique to synthesize perovskite ceramic powders. Understanding the reaction mechanisms and the factors that affect the particle morphologies is essential to optimize the hydrothermal processing. In this dissertation, the reaction mechanisms and nucleation processes in hydrothermally derived lead titanate (PbTiO3) are examined and established by morphological studies. The initial concentration of potassium hydroxide [KOH]i had a strong influence on the reaction. As [KOH] i increased from 0.01 M to 0.1 M to 1.0 M, the resultant morphology changed from irregular spherical to dendritic to faceted rectangular platelet morphology. The morphological evolution was well explained in the context of a supersaturation-nucleation relation. As the [KOH]i increased, the supersaturation increased and the nucleation mechanism changed from weak heterogeneous nucleation to strong heterogeneous nucleation or even homogeneous nucleation. These different nucleation mechanisms resulted in the different morphologies. Kinetic and morphological studies suggest that the reaction starting from nanocrystalline titania is dominated by dissolution-precipitation. The titanium precursors strongly affected the reaction. Increasing the particle size of precursors significantly reduced the reaction rate, especially at the low [KOH]i case. In situ transformations play important roles under the conditions of low [KOH] i and/or large particle size of precursors. Investigation using amorphous titania indicated that the nucleation of lead titanate at low and intermediate [KOH]i is via a in situ transformation while at high [KOH]i a dissolution-precipitation mechanism dominates. Ferro electricity of PbTiO3 also affects the particle morphology. The hydrothermal lead titanate particles could grow as a single domain during the processing. The ferroelectric polarization of PbTiO3 induced different local ionic environment between the positively and negatively charged surfaces, resulting a one-sided dendritic morphology at intermediate [KOH] i. The platelet morphology at high [KOH]i gave rise to a new type of size effect. For platelets with size less than a critical size of ˜70 nm, the domain polarization reoriented from perpendicular to the platelet during the processing, to parallel to the platelet after the particles were washed and dried (so that the depolarization energy builds up). This domain reorientation is attributed to strong depolarization effects and anisotropic geometry factors.

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 diagenetic overprint. We intend to come up with a process-oriented understanding of alteration parameters and products as the change in microstructure, texture and mineral phase needs a careful action when it comes to the interpretation of paleoclimate reconstruction data.

Hydrothermal synthesis of barium strontium titanate and bismuth titanate materials

NASA Astrophysics Data System (ADS)

Xu, Huiwen

Hydrothermal processing facilitates the synthesis of crystalline ceramic materials of varying composition or complex crystal structure. The present work can be divided into two parts. First is to study the low temperature hydrothermal synthesis of bismuth titanate. Second is to study both thermodynamic and kinetic aspects of the hydrothermally synthesized barium strontium titanate. A chelating agent was used to form a Bi-Ti gel precursor. By hydrothermally treating the Bi-Ti gel, crystalline bismuth titanate has been synthesized at 160°C for the first time. Microstructural evolution during the low temperature synthesis of bismuth titanate can be divided into two stages, including condensation of Bi-Ti gel particles and crystallization of bismuth titanate. Crystallization of bismuth titanate occurred by an in situ transformation mechanism at an early stage followed by a dissolution-reprecipitation mechanism. Phase separation was observed in hydrothermally synthesized barium strontium titanate (BST). By hydrothermally treating BST powders between 250°C--300°C, an asymmetrical miscibility gap was found in the BaTiO3-SrTiO 3 system at low temperatures (T ≤ 320°C). A subregular solid solution model was applied to calculate the equilibrium compositions and the Gibbs free energy of formation of BST solid solution at low temperatures (T ≤ 320°C). The Gibbs free energy of formation of Sr-rich BST phase is larger than that of Ba-rich BST phase. Kinetic studies of single phase BST solid solution at 80°C show that, compared to the BaTiO3 or Ba-rich BST, SrTiO3 and Sr-rich BST powders form at lower reaction rates.

Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA

USGS Publications Warehouse

Li, C.; Ripley, E.M.; Oberthur, T.; Miller, J.D.; Joslin, G.D.

2008-01-01

Stratigraphic offsets in the peak concentrations of platinum-group elements (PGE) and base-metal sulfides in the main sulfide zone of the Great Dyke and the precious metals zone of the Sonju Lake Intrusion have, in part, been attributed to the interaction between magmatic PGE-bearing base-metal sulfide assemblages and hydrothermal fluids. In this paper, we provide mineralogical and textural evidence that indicates alteration of base-metal sulfides and mobilization of metals and S during hydrothermal alteration in both mineralized intrusions. Stable isotopic data suggest that the fluids involved in the alteration were of magmatic origin in the Great Dyke but that a meteoric water component was involved in the alteration of the Sonju Lake Intrusion. The strong spatial association of platinum-group minerals, principally Pt and Pd sulfides, arsenides, and tellurides, with base-metal sulfide assemblages in the main sulfide zone of the Great Dyke is consistent with residual enrichment of Pt and Pd during hydrothermal alteration. However, such an interpretation is more tenuous for the precious metals zone of the Sonju Lake Intrusion where important Pt and Pd arsenides and antimonides occur as inclusions within individual plagioclase crystals and within alteration assemblages that are free of base-metal sulfides. Our observations suggest that Pt and Pd tellurides, antimonides, and arsenides may form during both magmatic crystallization and subsolidus hydrothermal alteration. Experimental studies of magmatic crystallization and hydrothermal transport/deposition in systems involving arsenides, tellurides, antimonides, and base metal sulfides are needed to better understand the relative importance of magmatic and hydrothermal processes in controlling the distribution of PGE in mineralized layered intrusions of this type. ?? Springer-Verlag 2007.

Geochemistry of hydrothermal vent fluids and its implications for subsurface processes at the active Longqi hydrothermal field, Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Ji, Fuwu; Zhou, Huaiyang; Yang, Qunhui; Gao, Hang; Wang, Hu; Lilley, Marvin D.

2017-04-01

The Longqi hydrothermal field at 49.6°E on the Southwest Indian Ridge was the first active hydrothermal field found at a bare-rock ultra-slow spreading mid-ocean ridge. Here we report the chemistry of the hydrothermal fluids, for the first time, that were collected from the S zone and the M zone of the Longqi field by gas-tight isobaric samplers by the HOV "Jiaolong" diving cruise in January 2015. According to H2, CH4 and other chemical data of the vent fluid, we suggest that the basement rock at the Longqi field is dominantly mafic. This is consistent with the observation that the host rock of the active Longqi Hydrothermal field is dominated by extensively distributed basaltic rock. It was very interesting to detect simultaneously discharging brine and vapor caused by phase separation at vents DFF6, DFF20, and DFF5 respectively, in a distance of about 400 m. Based on the end-member fluid chemistry and distance between the vents, we propose that there is a single fluid source at the Longqi field. The fluid branches while rising to the seafloor, and two of the branches reach S zone and M zone and phase separate at similar conditions of about 28-30.2 MPa and 400.6-408.3 °C before they discharge from the vents. The end-member fluid compositions of these vents are comparable with or within the range of variation of known global seafloor hydrothermal fluid chemical data from fast, intermediate and slow spreading ridges, which confirms that the spreading rate is not the key factor that directly controls hydrothermal fluid chemistry. The composition of basement rock, water-rock interaction and phase separation are the major factors that control the composition of the vent fluids in the Longqi field.

Ca and Sr Isotope Sytematics in Mid-Ocean Ridge Hydrothermal Fluids

NASA Astrophysics Data System (ADS)

Pester, N. J.; Syverson, D. D.; Higgins, J. A.; Seyfried, W. E., Jr.

2016-12-01

We report a comprehensive suite of Ca isotopic data (δ44/40Ca) from mid-ocean ridge hydrothermal fluids, standardized relative to seawater. Samples were acquired from 7 different vent fields on the EPR, JdFR and MAR during expeditions between 1999 and 2014. All endmember hydrothermal fluids (within analytical uncertainty) reflect an entirely MORB-dominated signal (-1.0 to -1.2 ‰). This rather uniform signal, despite variable fluid chemistries and a mixture of mafic to ultramafic host lithologies, is somewhat surprising given the noteworthy Ca concentrations in both the hydrothermal fluids and precursor seawater. One explanation for this observation involves the change in anhydrite (CaSO4) saturation with increasing temperature, and the molal concentration ratio of [Mg]:[Ca]:[SO4] in modern seawater of 53:10:28. The near quantitative removal of seawater Mg to silicate alteration phases, favorable at all temperatures, is largely charge balanced by exchange for basaltic Ca, and this process alone can account for the majority of the rock dominated δ44/40Casw signal. That these values are equivalent to MORB, however, suggests a high proportion of this Mg-Ca exchange occurs after seawater Ca precipitates as anhydrite in lower temperature (recharge) regimes of the hydrothermal system, aided by the low [Ca]/[SO4]. 87/86Sr ratios of hydrothermal fluids exhibit a seawater signal of 20 to 30% and Sr is therefore not quantitatively removed during incipient anhydrite formation. Strontium mobility in hydrothermal systems is still poorly understood, but the offset between the Ca and Sr isotopic signatures is consistent with near-equilibrium partitioning of Sr into anhydrite observed in recent experiments. Such observations from modern MOR systems place important constraints on the role of hydrothermal fluxes in paleo-seawater evolution, such as feedbacks involving significant variability in [Mg]:[Ca]:[SO4] ratios of seawater suggested over much of the Phanerozoic.

The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials

NASA Astrophysics Data System (ADS)

Dunne, Peter W.; Starkey, Chris L.; Gimeno-Fabra, Miquel; Lester, Edward H.

2014-01-01

Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control. Electronic supplementary information (ESI) available: Experimental details, refinement procedure, fluorescence spectra of ZnS samples. See DOI: 10.1039/c3nr05749f

Mineral-assisted production of benzene under hydrothermal conditions: Insights from experimental studies on C6 cyclic hydrocarbons

NASA Astrophysics Data System (ADS)

Venturi, Stefania; Tassi, Franco; Gould, Ian R.; Shock, Everett L.; Hartnett, Hilairy E.; Lorance, Edward D.; Bockisch, Christiana; Fecteau, Kristopher M.; Capecchiacci, Francesco; Vaselli, Orlando

2017-10-01

Volatile Organic Compounds (VOCs) are ubiquitously present at low but detectable concentrations in hydrothermal fluids from volcanic and geothermal systems. Although their behavior is strictly controlled by physical and chemical parameters, the mechanisms responsible for the production of most VOCs in natural environments are poorly understood. Among them, benzene, whose abundances were found to be relatively high in hydrothermal gases, can theoretically be originated from reversible catalytic reforming processes, i.e. multi-step dehydrogenation reactions, involving saturated hydrocarbons. However, this hypothesis and other hypotheses are difficult to definitively prove on the basis of compositional data obtained by natural gas discharges only. In this study, therefore, laboratory experiments were carried out to investigate the production of benzene from cyclic hydrocarbons at hydrothermal conditions, specifically 300 °C and 85 bar. The results of experiments carried out in the presence of water and selected powdered minerals, suggest that cyclohexane undergoes dehydrogenation to form benzene, with cyclohexene and cyclohexadiene as by-products, and also as likely reaction intermediates. This reaction is slow when carried out in water alone and competes with isomerization and hydration pathways. However, benzene formation was increased compared to these competing reactions in the presence of sulfide (sphalerite and pyrite) and iron oxide (magnetite and hematite) minerals, whereas no enhancement of any reaction products was observed in the presence of quartz. The production of thiols was observed in experiments involving sphalerite and pyrite, suggesting that sulfide minerals may act both to enhance reactivity and also as reactants after dissolution. These experiments demonstrate that benzene can be effectively produced at hydrothermal conditions through dehydrogenation of saturated cyclic organic structures and highlight the crucial role played by minerals in this process.

Seafloor weathering buffering climate: numerical experiments

NASA Astrophysics Data System (ADS)

Farahat, N. X.; Archer, D. E.; Abbot, D. S.

2013-12-01

Continental silicate weathering is widely held to consume atmospheric CO2 at a rate controlled in part by temperature, resulting in a climate-weathering feedback [Walker et al., 1981]. It has been suggested that weathering of oceanic crust of warm mid-ocean ridge flanks also has a CO2 uptake rate that is controlled by climate [Sleep and Zahnle, 2001; Brady and Gislason, 1997]. Although this effect might not be significant on present-day Earth [Caldeira, 1995], seafloor weathering may be more pronounced during snowball states [Le Hir et al., 2008], during the Archean when seafloor spreading rates were faster [Sleep and Zahnle, 2001], and on waterworld planets [Abbot et al., 2012]. Previous studies of seafloor weathering have made significant contributions using qualitative, generally one-box, models, and the logical next step is to extend this work using a spatially resolved model. For example, experiments demonstrate that seafloor weathering reactions are temperature dependent, but it is not clear whether the deep ocean temperature affects the temperature at which the reactions occur, or if instead this temperature is set only by geothermal processes. Our goal is to develop a 2-D numerical model that can simulate hydrothermal circulation and resulting alteration of oceanic basalts, and can therefore address such questions. A model of diffusive and convective heat transfer in fluid-saturated porous media simulates hydrothermal circulation through porous oceanic basalt. Unsteady natural convection is solved for using a Darcy model of porous media flow that has been extensively benchmarked. Background hydrothermal circulation is coupled to mineral reaction kinetics of basaltic alteration and hydrothermal mineral precipitation. In order to quantify seafloor weathering as a climate-weathering feedback process, this model focuses on hydrothermal reactions that influence carbon uptake as well as ocean alkalinity: silicate rock dissolution, calcium and magnesium leaching reactions, carbonate precipitation, and clay formation.

Groundwater flow processes and mixing in active volcanic systems: the case of Guadalajara (Mexico)

NASA Astrophysics Data System (ADS)

Hernández-Antonio, A.; Mahlknecht, J.; Tamez-Meléndez, C.; Ramos-Leal, J.; Ramírez-Orozco, A.; Parra, R.; Ornelas-Soto, N.; Eastoe, C. J.

2015-02-01

Groundwater chemistry and isotopic data from 40 production wells in the Atemajac and Toluquilla Valleys, located in and around the Guadalajara metropolitan area, were determined to develop a conceptual model of groundwater flow processes and mixing. Multivariate analysis including cluster analysis and principal component analysis were used to elucidate distribution patterns of constituents and factors controlling groundwater chemistry. Based on this analysis, groundwater was classified into four groups: cold groundwater, hydrothermal water, polluted groundwater and mixed groundwater. Cold groundwater is characterized by low temperature, salinity, and Cl and Na concentrations and is predominantly of Na-HCO3 type. It originates as recharge at Primavera caldera and is found predominantly in wells in the upper Atemajac Valley. Hydrothermal water is characterized by high salinity, temperature, Cl, Na, HCO3, and the presence of minor elements such as Li, Mn and F. It is a mixed HCO3 type found in wells from Toluquilla Valley and represents regional flow circulation through basaltic and andesitic rocks. Polluted groundwater is characterized by elevated nitrate and sulfate concentrations and is usually derived from urban water cycling and subordinately from agricultural practices. Mixed groundwaters between cold and hydrothermal components are predominantly found in the lower Atemajac Valley. Tritium method elucidated that practically all of the sampled groundwater contains at least a small fraction of modern water. The multivariate mixing model M3 indicates that the proportion of hydrothermal fluids in sampled well water is between 13 (local groundwater) and 87% (hydrothermal water), and the proportion of polluted water in wells ranges from 0 to 63%. This study may help local water authorities to identify and quantify groundwater contamination and act accordingly.

Massive sulfide deposition and trace element remobilization in the Middle Valley sediment-hosted hydrothermal system, northern Juan de Fuca Rdge

USGS Publications Warehouse

Houghton, J.L.; Shanks, Wayne C.; Seyfried, W.E.

2004-01-01

The Bent Hill massive sulfide deposit and ODP Mound deposit in Middle Valley at the northernmost end of the Juan de Fuca Ridge are two of the largest modern seafloor hydrothermal deposits yet explored. Trace metal concentrations of sulfide minerals, determined by laser-ablation ICP-MS, were used in conjunction with mineral paragenetic studies and thermodynamic calculations to deduce the history of fluid-mineral reactions during sulfide deposition. Detailed analyses of the distribution of metals in sulfides indicate significant shifts in the physical and chemical conditions responsible for the trace element variability observed in these sulfide deposits. Trace elements (Mn, Co, Ni, As, Se, Ag, Cd, Sb, Pb, and Bi) analyzed in a representative suite of 10 thin sections from these deposits suggest differences in conditions and processes of hydrothermal alteration resulting in mass transfer of metals from the center of the deposits to the margins. Enrichments of some trace metals (Pb, Sb, Cd, Ag) in sphalerite at the margins of the deposits are best explained by dissolution/reprecipitation processes consistent with secondary remineralization. Results of reaction-path models clarify mechanisms of mass transfer during remineralization of sulfide deposits due to mixing of hydrothermal fluids with seawater. Model results are consistent with patterns of observed mineral paragenesis and help to identify conditions (pH, redox, temperature) that may be responsible for variations in trace metal concentrations in primary and secondary minerals. Differences in trace metal distributions throughout a single deposit and between nearby deposits at Middle Valley can be linked to the history of metal mobilization within this active hydrothermal system that may have broad implications for sulfide ore formation in other sedimented and unsedimented ridge systems. ?? 2004 Elsevier Ltd.

Siderophore production in high iron environments

NASA Astrophysics Data System (ADS)

Bennett, S. A.; Hoffman, C. L.; Moffett, J. W.; Edwards, K. J.

2010-12-01

Up until recently, the geochemical cycling of Fe in deep sea hydrothermal plumes has assumed to be inorganically dominated, resulting in quantitative precipitation of all hydrothermally sourced Fe to the seafloor. Recent detection of organic Fe binding ligands within both the dissolved and particulate phase (Bennett et al., 2008; Toner et al., 2009), suggests that hydrothermally sourced Fe may be important on a global scale (Tagliabue et al., 2010). The source of these organic ligands is currently unknown; hypotheses include the possible entrainment of organic carbon from the biologically rich diffuse flow areas, or in-situ production from microbial processes. However, the microbial production of organic ligands is only expected when Fe is a limited micronutrient, which is not the case in the hydrothermal environment. The importance of Fe cycling microorganisms within hydrothermal systems was previously overlooked due to the poor energetics with regards to Fe oxidation and reduction. But their recent detection within the hydrothermal system, both around low temperature Fe rich mineral deposits and within hydrothermal plumes (Edwards et al., 2004; Sylvan et al., In prep) suggests that they may have an important role in the hydrothermal Fe cycle, potentially resulting in an interplay between Fe and organic carbon. Within the laboratory, we have carried out experiments to investigate an Fe oxidizing bacteria in a variety of high Fe environments. We have detected both the production of siderophores and an increase in reduced Fe when the Fe oxidizing bacteria is exposed to both Fe(III) and Fe(II) rich minerals. The role of these microbes in the mineral dissolution of Fe sulfides along the seafloor and within the hydrothermal plume, may have important implications on the speciation of Fe and the role of siderophores in the marine environment. Bennett, S.A. et al. 2008. EPSL, 270: 157-167. Edwards, K.J. et al. 2004. Geomicrobiology Journal, 21: 393-404. Sylvan, J.B. et al. In prep for Geobiology Tagliabue, A. et al. 2010. Nature Geoscience, 3: 252-256. Toner, B.M.,et al. 2009. Nature Geoscience, 2: 197 - 201.

Thiols in Hydrothermal Solution: Standard Partial Molal Properties and Their Role in the Organic Geochemistry of Hydrothermal Environments

NASA Technical Reports Server (NTRS)

Schulte, Mitchell D.; Rogers, Karyn L.; DeVincenzi, D. (Technical Monitor)

2001-01-01

Modern seafloor hydrothermal systems are locations where great varieties of geochemistry occur due to the enormous disequilibrium between vent fluids and seawater. The disequilibrium geochemistry has been hypothesized to include reactions to synthesize organic compounds. Despite the incomplete understanding of the carbon budget in hydrothermal systems, the organic geochemistry of these sites has received little attention. Experimental simulations of these environments, however, indicate that organic compounds may have difficulty forming in a purely aqueous environment. On the other hand, thiols, thioesters and disulfides have been implicated as reaction intermediates between CO or CO2 in experiments of carbon reduction in hydrothermal environments, as well as in a variety of biological processes and other abiotic reactions. The reduction of CO2 to thesis, for example, is observed using the FeS-H2S/FeS2 couple to provide the reducing power. We have used recent advances in theoretical geochemistry to estimate the standard partial moral thermodynamic properties and parameters for the revised Helgeson-Kirkham-Flowers equation of state for aqueous straight-chain alkyl thesis. With these data and parameters we have evaluated the role that organic sulfur compounds may play as reaction intermediates during organic compound synthesis. We conclude that organic sulfur compounds may hold the key to the organic chemistry leading to the origin of life in hydrothermal settings. These results may also explain the presence of sulfur in a number of biomolecules present in ancient thermophilic microorganisms.

Part II. Hydrothermal steel slag valorization: hydrogen and nano-magnetite production

NASA Astrophysics Data System (ADS)

Crouzet, Camille; Brunet, Fabrice; Recham, Nadir; Auzende, Anne-Line; Findling, Nathaniel; Magnin, Valérie; Ferrasse, Jean-Henry; Goffé, Bruno

2017-10-01

The effect of acidic conditions (in a pH range of 3 to 6) and temperature on the kinetics of the hydrothermal oxidation of ferrous iron contained in BOF steel slag has been tested in the 150 – 350°C range for acid acetic concentrations from 0 to 4M. Reaction progress was monitored with the amount of produced H2. Higher temperature and lower pH are found to enhance the hydrothermal oxidation kinetics of the slag. These two parameters are believed to increase iron dissolution rate which has already been identified as the rate limiting step of the hydrothermal oxidation of pure FeO. An activation energy of 28 × 4 kJ/mole is found for the hydrothermal oxidation of the steel slag which compares very well with that of pure FeO under similar conditions. In the case of the slag run in water at 300°C for 70.5 hours, magnetite product has been separated magnetically and characterized. Particles were found to fall in three size ranges: 10 – 30 nm, 100 – 300 nm and 1 – 10 µm. The smallest fraction (10 – 30 nm) is comparable to the 10 – 20 nm size range that is achieved when nanomagnetite are synthesized by co-precipitation methods. Obviously, the production of nanomagnetite enhances the economic interest of the hydrothermal processing of steel slags, which has already proven its capacity to produce high-purity H2.

Si-Metasomatism During Serpentinization of Jurassic Ultramafic Sea-floor: a Comparative Study

NASA Astrophysics Data System (ADS)

Vogel, M.; Frueh-Green, G. L.; Boschi, C.; Schwarzenbach, E. M.

2014-12-01

The Bracco-Levanto ophiolitic complex (northwestern Italy) represents one of the largest and better-exposed ophiolitic successions in the Northern Apennines. It is considered to be a fragment of heterogeneous Jurassic lithosphere that records tectono-magmatic and alteration histories similar to those documented along the Mid-Atlantic Ridge (MAR), such as at the 15°20'N area and the Atlantis Massif at 30°N. Structural and petrological studies on these rocks provide constraints on metamorphic/deformation processes during formation and hydrothermal alteration of the Jurassic oceanic lithosphere. We present a petrological and geochemical study of serpentinization processes and fluid-rock interaction in the Bracco-Levanto ophiolitic complex and compare these to published data from modern oceanic hydrothermal systems, such as the Lost City hydrothermal field hosted in serpentinites on the Atlantis Massif. Major element and mineral compositional data allow us to distinguish a multiphase history of alteration characterized by: (1) widespread Si-metasomatism during progressive serpentinization, and (2) multiple phases of veining and carbonate precipitation associated with circulation of seawater in the shallow ultramafic-dominated portions of the Jurassic seafloor, resulting in the formation of ophicalcites. In detail, regional variations in Si, Mg and Al content are observed in zones of ophicalcite formation, indicating metasomatic reactions and Si-Al transport during long-lived fluid-rock interaction and channelling of hydrothermal fluids. Rare earth element and isotopic analysis indicate that the Si-rich fluids are derived from alteration of pyroxenes to talc and tremolite in ultramafic rocks at depth. Comparison with serpentinites from the Atlantis Massif and 15°20'N indicates a similar degree of Si-enrichment in the modern seafloor and suggests that Si-metasomatism may be a fundamental process associated with serpentinization at slow-spreading ridge environments. However, in contrast to metasomatic processes at the MAR, we find no geochemical evidence for a gabbroic source of the fluids, and thus, processes leading to Si-rich fluids can be variable in these environments.

Continent-Wide Maps of Lg Coda Q Variation and Rayleigh-wave Attenuation Variation for Eurasia

DTIC Science & Technology

2007-01-30

lithosphere and crustal strain lead us to infer that fluids, originating by hydrothermal release from subducting lithosphere or other upper mantle heat...relatively low Qo values in the Arabian Peninsula are produced by fluids that have been released in the upper mantle by hydrothermal processes and have...Advection of plumes in mantle flow: Implications for hotspot motion, mantle viscosity and plume distribution, Geophys. J. Int., 132, 412–434. Talebian, M

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

Time-lapse characterization of hydrothermal seawater and microbial interactions with basaltic tephra at Surtsey Volcano

NASA Astrophysics Data System (ADS)

Jackson, M. D.; Gudmundsson, M. T.; Bach, W.; Cappelletti, P.; Coleman, N. J.; Ivarsson, M.; Jónasson, K.; Jørgensen, S. L.; Marteinsson, V.; McPhie, J.; Moore, J. G.; Nielson, D.; Rhodes, J. M.; Rispoli, C.; Schiffman, P.; Stefánsson, A.; Türke, A.; Vanorio, T.; Weisenberger, T. B.; White, J. D. L.; Zierenberg, R.; Zimanowski, B.

2015-12-01

A new International Continental Drilling Program (ICDP) project will drill through the 50-year-old edifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963-1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions. Abstracts of research projects are posted at http://surtsey.icdp-online.org.

Abundance and Distribution of Diagnostic Carbon Fixation Genes in a Deep-Sea Hydrothermal Gradient Ecosystem

NASA Astrophysics Data System (ADS)

Blumenfeld, H. N.; Kelley, D. S.; Girguis, P. R.; Schrenk, M. O.

2010-12-01

The walls of deep-sea hydrothermal vent chimneys sustain steep thermal and chemical gradients resulting from the mixing of hot (350°C+) hydrothermal fluids with cold, oxygenated seawater. The chemical disequilibrium generated from this process has the potential to drive numerous chemolithoautotrophic metabolisms, many of which have been demonstrated to be operative in microbial pure cultures. In addition to the well-known Calvin Cycle, at least five additional pathways have been discovered including the Reverse Tricarboxylic Acid Cycle (rTCA), the Reductive Acetyl-CoA pathway, and the 3-hydroxyproprionate pathway. Most of the newly discovered pathways have been found in thermophilic and hyperthermophilic Bacteria and Archaea, which are the well represented in microbial diversity studies of hydrothermal chimney walls. However, to date, little is known about the environmental controls that impact various carbon fixation pathways. The overlap of limited microbial diversity with distinct habitat conditions in hydrothermal chimney walls provides an ideal setting to explore these relationships. Hydrothermal chimney walls from multiple structures recovered from the Juan de Fuca Ridge in the northeastern Pacific were sub-sampled and analyzed using PCR-based assays. Earlier work showed elevated microbial abundances in the outer portions of mature chimney walls, with varying ratios of Archaea to Bacteria from the outer to inner portions of the chimneys. Common phylotypes identified in these regions included Epsilonproteobacteria, Gammaproteobacteria, and Desulfurococcales. Total genomic DNA was extracted from mineralogically distinct niches within these structures and queried for genes coding key regulatory enzymes for each of the well studied carbon fixation pathways. Preliminary results show the occurrence of genes representing rTCA cycle (aclB) and methyl coenzyme A reductase (mcrA) - a proxy for the Reductive Acetyl-CoA Pathway within interior portion of mature hydrothermal chimneys. Ongoing analyses are aimed at quantifying the abundances of these diagnostic carbon fixation genes within the hydrothermal chimney gradients. These data are being compared to a broad array of contextual data to provide insight into the environmental and biological controls that may impact the distribution of the various carbon fixation pathways. Application of genomic approaches to the hydrothermal chimney ecosystem will provide insight into the microbial ecology of such structures and refine our ability to measure autotrophy in hydrothermal habitats sustained by chemical energy.

Coupled cycling of Fe and organic carbon in submarine hydrothermal systems: Modelling approach

NASA Astrophysics Data System (ADS)

Legendre, Louis; German, Christopher R.; Sander, Sylvia G.; Niquil, Nathalie

2014-05-01

It has been recently proposed that hydrothermal plumes may be a significant source of dissolved Fe to the oceans. In order to assess this proposal, we investigated the fate of dissolved Fe released from hydrothermal systems to the overlying ocean using an approach that combined modelling and field values. We based our work on a consensus conceptual model developed by members of SCOR-InterRidge Working Group 135. The model was both complex enough to capture the main processes of dissolved Fe released from hydrothermal systems and chemical transformation in the hydrothermal plume, and simple enough to be parameterized with existing field data. It included the following flows: Fe, water and heat in the high temperature vent fluids, in the fluids diffusing around the vent, and in the entrained seawater in the buoyant plume; Fe precipitation in polymetallic sulphides near the vent; transport of Fe in the non-buoyant plume, and both its precipitation in particles onto the sea bottom away from the vent and dissolution into deep-sea waters. In other words, there were three Fe input flows into the buoyant hydrothermal plume (vent-fluids; entrained diffuse flow; entrained seawater) and three Fe output flows (sedimentation from the buoyant plume as polymetallic sulfides; sedimentation from the non-buoyant plume in particulate form; export to the deep ocean in dissolved or nanoparticulate form). The output flows balanced the input flows. We transformed the conceptual model into equations, and parameterized these with field data. To do so, we assumed that all hydrothermal systems, globally, can be represented by the circumstances that prevail at the EPR 9°50'N hydrothermal field, although we knew this assumption not to be accurate. We nevertheless achieved, by following this approach, two important goals, i.e. we could assemble into a coherent framework, for the first time, several discrete data sets acquired independently over decades of field work, and we could obtain model results that were consistent with recent field observations. We used our model to explore scenarios of Fe emissions and transformations under various constraints. The modelling exercises indicated that the provision of significant amounts of dissolved Fe to the oceans by hydrothermal plumes was consistent with realistic model parameters. This supported the proposition that hydrothermal systems play significant roles in the global biogeochemical Fe cycle.

Lipid synthesis under hydrothermal conditions by Fischer-Tropsch-type reactions

NASA Technical Reports Server (NTRS)

McCollom, T. M.; Ritter, G.; Simoneit, B. R.

1999-01-01

Ever since their discovery in the late 1970's, mid-ocean-ridge hydrothermal systems have received a great deal of attention as a possible site for the origin of life on Earth (and environments analogous to mid-ocean-ridge hydrothermal systems are postulated to have been sites where life could have originated or Mars and elsewhere as well). Because no modern-day terrestrial hydrothermal systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in hydrothermal systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 degrees C for 2-3 days and produces lipid compounds ranging from C2 to > C35 which consist of n-alkanols, n-alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.

Lipid Synthesis Under Hydrothermal Conditions by Fischer- Tropsch-Type Reactions

NASA Astrophysics Data System (ADS)

McCollom, Thomas M.; Ritter, Gilles; Simoneit, Bernd R. T.

1999-03-01

Ever since their discovery in the late 1970's, mid-ocean-ridge hydrothermal systems have received a great deal of attention as a possible site for the origin of life on Earth (and environments analogous to mid-ocean-ridge hydrothermal systems are postulated to have been sites where life could have originated on Mars and elsewhere as well). Because no modern-day terrestrial hydrothermal systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in hydrothermal systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 °C for 2-3 days and produces lipid compounds ranging from C2 to >C35 which consist of n-alkanols, n- alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.

Lipid synthesis under hydrothermal conditions by Fischer-Tropsch-type reactions.

PubMed

McCollom, T M; Ritter, G; Simoneit, B R

1999-03-01

Ever since their discovery in the late 1970's, mid-ocean-ridge hydrothermal systems have received a great deal of attention as a possible site for the origin of life on Earth (and environments analogous to mid-ocean-ridge hydrothermal systems are postulated to have been sites where life could have originated or Mars and elsewhere as well). Because no modern-day terrestrial hydrothermal systems are free from the influence of organic compounds derived from biologic processes, laboratory experiments provide the best opportunity for confirmation of the potential for organic synthesis in hydrothermal systems. Here we report on the formation of lipid compounds during Fischer-Tropsch-type synthesis from aqueous solutions of formic acid or oxalic acid. Optimum synthesis occurs in stainless steel vessels by heating at 175 degrees C for 2-3 days and produces lipid compounds ranging from C2 to > C35 which consist of n-alkanols, n-alkanoic acids, n-alkenes, n-alkanes and alkanones. The precursor carbon sources used are either formic acid or oxalic acid, which disproportionate to H2, CO2 and probably CO. Both carbon sources yield the same lipid classes with essentially the same ranges of compounds. The synthesis reactions were confirmed by using 13C labeled precursor acids.

Vapor-phase hydrothermal transformation of HTiOF3 intermediates into {001} faceted anatase single-crystalline nanosheets.

PubMed

Liu, Porun; Wang, Yun; Zhang, Haimin; An, Taicheng; Yang, Huagui; Tang, Zhiyong; Cai, Weiping; Zhao, Huijun

2012-12-07

For the first time, a facile, one-pot hydrofluoric acid vapor-phase hydrothermal (HF-VPH) method is demonstrated to directly grow single-crystalline anatase TiO(2) nanosheets with 98.2% of exposed {001} faceted surfaces on the Ti substrate via a distinctive two-stage formation mechanism. The first stage produces a new intermediate crystal (orthorhombic HTiOF(3) ) that is transformed into anatase TiO(2) nanosheets during the second stage. The findings reveal that the HF-VPH reaction environment is unique and differs remarkably from that of liquid-phase hydrothermal processes. The uniqueness of the HF-VPH conditions can be readily used to effectively control the nanostructure growth. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The rapid size- and shape-controlled continuous hydrothermal synthesis of metal sulphide nanomaterials.

PubMed

Dunne, Peter W; Starkey, Chris L; Gimeno-Fabra, Miquel; Lester, Edward H

2014-02-21

Continuous flow hydrothermal synthesis offers a cheap, green and highly scalable route for the preparation of inorganic nanomaterials which has predominantly been applied to metal oxide based materials. In this work we report the first continuous flow hydrothermal synthesis of metal sulphide nanomaterials. A wide range of binary metal sulphides, ZnS, CdS, PbS, CuS, Fe(1-x)S and Bi2S3, have been synthesised. By varying the reaction conditions two different mechanisms may be invoked; a growth dominated route which permits the formation of nanostructured sulphide materials, and a nucleation driven process which produces nanoparticles with temperature dependent size control. This offers a new and industrially viable route to a wide range of metal sulphide nanoparticles with facile size and shape control.

Fractionation of rapeseed straw by hydrothermal/dilute acid pretreatment combined with alkali post-treatment for improving its enzymatic hydrolysis.

PubMed

Chen, Bo-Yang; Zhao, Bao-Cheng; Li, Ming-Fei; Liu, Qiu-Yun; Sun, Run-Cang

2017-02-01

The aim of the research was to evaluate the effect of combined treatments on fermentable sugar production from rapeseed straw. An optimum condition was found to be the combination of hydrothermal pretreatment at 180°C for 45min and post-treatment by 2% NaOH at 100°C for 2h, which was based on the quantity of monosaccharides released during enzymatic hydrolysis. As compared with the raw material without treatment, the combination of hydrothermal pretreatment and alkali post-treatment resulted in a significant increase of the saccharification rate by 5.9times. This process potentially turned rapeseed straw into value added products in accordance with the biorefinery concept. Copyright © 2016 Elsevier Ltd. All rights reserved.

What governs the enrichment of Pb in the continental crust? An answer from the Mexican Volcanic Belt

NASA Astrophysics Data System (ADS)

Goldstein, S. L.; Lagatta, A.; Langmuir, C. H.; Straub, S. M.; Martin-Del-Pozzo, A.

2009-12-01

One of Al Hofmann’s many important contributions to our understanding of geochemical cycling in the Earth is the observation that Pb behaves like the light rare earth elements Ce and Nd during melting to form oceanic basalts, but is enriched in the continental crust compared to the LREE by nearly an order of magnitude (Hofmann et al. 1986). This is unusual behavior, and has been called one of the Pb paradoxes, since in most cases, the ratios of elements are effectively the same in the continental crust and oceanic basalts if they show similar mantle melting behavior. One of several mechanisms suggested to mediate this special enrichment is hydrothermal circulation at ocean ridges, which preferentially transports Pb compared to the REE from the interior of the ocean crust to the surface. We confirm the importance of hydrothermal processes at the East Pacific to mediate Pb enrichment at the Trans-Mexican Volcanic Belt (TMVB, through comparison of Pb isotope and Ce/Pb ratios of TMVB lavas with sediments from DSDP Site 487 near the Middle America trench. The lavas of the Trans-Mexican Volcanic Belt include “high Nb” alkali basalts (HNAB), whose trace element patterns lack subduction signatures. The HNAB basalts and hydrothermally affected sediments from DSDP 487, form end-members that bound calcalkaline lavas from volcanoes Colima, Toluca, Popocatépetl, and Malinche in Ce/Pb versus Pb isotope space. The HNAB represent the high Ce/Pb and high Pb-isotope end-member. The hydrothermal sediments have Pb isotopes like Pacific MORB but Ce/Pb ratios typical of the arcs and the continental crust, and an order of magnitude lower than MORB. No analyzed calcalkaline lavas are have compositions outside of the bounds formed by the HNAB and the hydrothermal sediments. The Ce/Pb and Pb isotope ratios show that the calcalkaline lava compositions are inconsistent with contributions from HNAB and EPR MORB, rather the contributions are from HNAB upper mantle and subducted hydrothermal sediments. The Trans-Mexican Volcanic Belt data confirm the two-step process of Pb enrichment in the arc lavas (and more generally in the continental crust). In the first step, hydrothermal processes at the East Pacific Rise preferentially transport Pb from the basaltic oceanic crust to surface sediments. In the second step, during subduction, these sediments are the main source of asthenospheric mantle-derived Pb to the lavas. Our data also confirm the importance of subduction contributions to the Quaternary Mexican arc, despite the >40 km thick continental crust. Ref: Hofmann et al. (1986) EPSL 79 p. 33-45.

Total recovery of the waste of two-phase olive oil processing: isolation of added-value compounds.

PubMed

Fernández-Bolaños, Juan; Rodríguez, Guillermo; Gómez, Esther; Guillén, Rafael; Jiménez, Ana; Heredia, Antonia; Rodríguez, Rocío

2004-09-22

A process for the value addition of solid waste from two-phase olive oil extraction or "alperujo" that includes a hydrothermal treatment has been suggested. In this treatment an autohydrolysis process occurs and the solid olive byproduct is partially solubilized. From this water-soluble fraction can be obtained besides the antioxidant hydroxytyrosol several other compounds of high added value. In this paper three different samples of alperujo were characterized and subjected to a hydrothermal treatment with and without acid catalyst. The main soluble compounds after the hydrolysis were represented by monosaccharides xylose, arabinose, and glucose; oligosaccharides, mannitol and products of sugar destruction. Oligosaccharides were separated by size exclusion chromatography. It was possible to get highly purified mannitol by applying a simple purification method.

The physical hydrology of magmatic-hydrothermal systems: High-resolution 18O records of magmatic-meteoric water interaction from the Yankee Lode tin deposit (Mole Granite, Australia)

NASA Astrophysics Data System (ADS)

Fekete, Szandra; Weis, Philipp; Driesner, Thomas; Heinrich, Christoph A.; Baumgartner, Lukas; Bouvier, Anne-Sophie

2016-04-01

Magmatic-hydrothermal ore deposits are important economic Cu, Au, Mo and Sn resources (Sillitoe, 2010, Kesler, 1994). The ore formation is a result of superimposed enrichment processes and metals can precipitate due to fluid-rock interaction and/or temperature drop caused by convection or mixing with meteoric fluid (Heinrich and Candela 2014). Microthermometry and LA-ICP MS trace element analyses of fluid inclusions of a well-characterized quartz sample from the Yankee Lode quartz-cassiterite vein deposit (Mole Granite, Australia) suggest that tin precipitation was driven by dilution of hot magmatic water by meteoric fluids (Audétat et al.1998). High resolution in situ oxygen isotope measurements of quartz have the potential to detect changing fluid sources during the evolution of a hydrothermal system. We analyzed the euhedral growth zones of this previously well-studied quartz sample. Growth temperatures are provided by Audétat et al. (1998) and Audétat (1999). Calculated δ 18O values of the quartz- and/or cassiterite-precipitating fluid show significant variability through the zoned crystal. The first and second quartz generations (Q1 and Q2) were precipitated from a fluid of magmatic isotopic composition with δ 18O values of ˜ 8 - 10 ‰. δ 18O values of Q3- and tourmaline-precipitating fluids show a transition from magmatic δ 18O values of ˜ 8 ‰ to ˜ -5 ‰. The outermost quartz-chlorite-muscovite zone was precipitated from a fluid with a significant meteoric water component reflected by very light δ 18O values of about -15 ‰ which is consistent with values found by previous studies (Sun and Eadington, 1987) using conventional O-isotope analysis of veins in the distal halo of the granite intrusion. Intense incursion of meteoric water during Q3 precipitation (light δ 18O values) agrees with the main ore formation event, though the first occurrence of cassiterite is linked to Q2 precipitating fluid with magmatic-like isotope signature. This apparent discrepancy can be explained by the presence of a fluid of meteoric origin that was isotopically equilibrated with a hot, but already solidified and fractured granitic intrusion under rock-dominated conditions prior their transfer to the cold ore deposition site (Heinrich, 1990). Conversely, in porphyry copper systems meteoric fluid incursion has been assumed to participate in formation of peripheral or post-mineralization processes (Bowman et al., 1987; Sillitoe, 2010; Williams-Jones and Migdisov, 2014). However, recent numerical simulations of porphyry copper systems identify a significant role of meteoric fluids for the enrichment process, providing a cooling mechanism for metal-rich fluids expelled from an upper crustal magma chamber (Weis et al. 2012, Weis 2015). Furthermore, new petrographic and fluid inclusion work of ore-mineralized quartz veins (Landtwing et al., 2010; Stefanova et al., 2014) indicates lower (˜ 450r{ }C) than magmatic fluid temperatures for copper precipitation. Given that the Yankee Lode study validated the capability of high resolution, in situ δ 18O analysis to trace meteoric water incursion, we will apply this method to hydrothermal quartz samples from two significant porphyry copper deposits (Bingham Canyon, USA and Elatsite, Bulgaria). By this we intend to better constrain a potential role of meteoric water incursion in porphyry copper ore precipitation. REFERENCES Audétat, A., Günther, D., Heinrich, C. A. 1998: Formation of a Magmatic-Hydrothermal Ore Deposit: Insights with LA-ICP-MS Analysis of Fluid Inclusions: Science, 279, 2091-2094. Audétat, A. 1999: The magmatic-hydrothermal evolution of the Sn/W-mineralized Mole Granite (Eastern Australia): PhD Thesis, 211. Bowman, J. R., Parry, W. T., Kropp, W. P., and Kruer, S. A., 1987: Chemical and isotopic evolution of hydrothermal solutions at Bingham, Utah: Economic Geology, 82, 395-428. Heinrich, C.A. 1990: The Chemistry of Hydrothermal Tin(-Tungsten) Ore Deposition: Economic Geology, 85, 457-481. Heinrich, C. A., and Candela, P. A. 2014: 13.1 - Fluids and Ore Formation in the Earth's Crust, in Holland, H. D., and Turekian, K. K., eds., Treatise on Geochemistry (Second Edition): Oxford, Elsevier, 1-28. Kesler, S. E., 1994: Mineral Resources, economics and the environment, New York, McMillan, 391. Sillitoe, R. H., 2010: Porphyry copper systems: Economic Geology (Invited Special Paper), 105, 3-41. Sun, S. and Eadington, J. 1987: Oxygen Isotope Evidence for the Mixing of Magmatic and Meteoric Waters during Tin Mineralization in the Mole Granite, New South Wales, Australia: Economic Geology, 82, 43-52. Weis, P., Driesner, T., & Heinrich, C.A. 2012: Porphyry-Copper Ore Shells Form At Stable Pressure Temperature Fronts Within Dynamic Fluid Plumes: Science, 338, 1613-1616. Williams-Jones, A. E., and Migdisov, A. A., 2014: Experimental Constraints on the Transport and Deposition of Metals in Ore-Forming Hydrothermal Systems: Economic Geology, Special Publication, 18, 77-95.

Constraints on hydrocarbon and organic acid abundances in hydrothermal fluids at the Von Damm vent field, Mid-Cayman Rise (Invited)

NASA Astrophysics Data System (ADS)

McDermott, J. M.; Seewald, J.; German, C. R.; Sylva, S. P.

2013-12-01

The generation of organic compounds in vent fluids has been of interest since the discovery of seafloor hydrothermal systems, due to implications for the sustenance of present-day microbial populations and their potential role in the origin of life on early Earth. Possible sources of organic compounds in hydrothermal systems include microbial production, thermogenic degradation of organic material, and abiotic synthesis. Abiotic organic synthesis reactions may occur during active circulation of seawater-derived fluids through the oceanic crust or within olivine-hosted fluid inclusions containing carbon-rich magmatic volatiles. H2-rich end-member fluids at the Von Damm vent field on the Mid-Cayman Rise, where fluid temperatures reach 226°C, provide an exciting opportunity to examine the extent of abiotic carbon transformations in a highly reducing system. Our results indicate multiple sources of carbon compounds in vent fluids at Von Damm. An ultramafic-influenced hydrothermal system located on the Mount Dent oceanic core complex at 2350 m depth, Von Damm vent fluids contain H2, CH4, and C2+ hydrocarbons in high abundance relative to basalt-hosted vent fields, and in similar abundance to other ultramafic-hosted systems, such as Rainbow and Lost City. The CO2 content and isotopic composition in end-member fluids are virtually identical to bottom seawater, suggesting that seawater DIC is unchanged during hydrothermal circulation of seawater-derived fluids. Accordingly, end-member CH4 that is present in slightly greater abundance than CO2 cannot be generated from reduction of aqueous CO2 during hydrothermal circulation. We postulate that CH4 and C2+ hydrocarbons that are abundantly present in Von Damm vent fluids reflect leaching of fluids from carbon- and H2-rich fluid inclusions hosted in plutonic rocks. Geochemical modeling of carbon speciation in the Von Damm fluids suggests that the relative abundances of CH4, C2+ hydrocarbons, and CO2 are consistent with thermodynamic equilibrium at higher temperatures and more reducing conditions than those observed in the Von Damm vent fluids. These findings are consistent with a scenario in which n-alkanes form abiotically within a high-H2, carbon-rich olivine-hosted fluid inclusion, and are subsequently liberated and transported to the seafloor during hydrothermal alteration of the lower crustal rocks exposed at the Mount Dent oceanic core complex. Mixed fluids at Von Damm show depletions in CO2 and H2, relative to conservative mixing. Multiple S isotope measurements indicate that the H2 sink cannot be attributed to sulfate reduction. Thermodynamic constraints indicate that high-H2 conditions support the active formation of formate via reduction of dissolved CO2 during hydrothermal circulation - a process that has also been described at the Lost City vent field - and could account for the concurrent depletions in CO2 and H2. The transformation of inorganic carbon to organic compounds via two distinct pathways in modern seafloor hydrothermal vents validates theoretical and experimental conceptual models regarding processes occurring in the crust and during hydrothermal circulation, and is relevant to supporting life in vent ecosystems.

Eruptions at Lone Star geyser, Yellowstone National Park, USA: 2. Constraints on subsurface dynamics

USGS Publications Warehouse

Vandemeulebrouck, Jean; Sohn, Robert A.; Rudolph, Maxwell L.; Hurwitz, Shaul; Manga, Michael; Johnston, Malcolm J.S.; Soule, S. Adam; McPhee, Darcy K.; Glen, Jonathan M.G.; Karlstrom, Leif; Murphy, Fred

2014-01-01

We use seismic, tilt, lidar, thermal, and gravity data from 32 consecutive eruption cycles of Lone Star geyser in Yellowstone National Park to identify key subsurface processes throughout the geyser's eruption cycle. Previously, we described measurements and analyses associated with the geyser's erupting jet dynamics. Here we show that seismicity is dominated by hydrothermal tremor (~5–40 Hz) attributed to the nucleation and/or collapse of vapor bubbles. Water discharge during eruption preplay triggers high-amplitude tremor pulses from a back azimuth aligned with the geyser cone, but during the rest of the eruption cycle it is shifted to the east-northeast. Moreover, ~4 min period ground surface displacements recur every 26 ± 8 min and are uncorrelated with the eruption cycle. Based on these observations, we conclude that (1) the dynamical behavior of the geyser is controlled by the thermo-mechanical coupling between the geyser conduit and a laterally offset reservoir periodically filled with a highly compressible two-phase mixture, (2) liquid and steam slugs periodically ascend into the shallow crust near the geyser system inducing detectable deformation, (3) eruptions occur when the pressure decrease associated with overflow from geyser conduit during preplay triggers an unstable feedback between vapor generation (cavitation) and mass discharge, and (4) flow choking at a constriction in the conduit arrests the runaway process and increases the saturated vapor pressure in the reservoir by a factor of ~10 during eruptions.

Fracturing And Liquid CONvection

DOE Office of Scientific and Technical Information (OSTI.GOV)

2012-02-29

FALCON has been developed to enable simulation of the tightly coupled fluid-rock behavior in hydrothermal and engineered geothermal system (EGS) reservoirs, targeting the dynamics of fracture stimulation, fluid flow, rock deformation, and heat transport in a single integrated code, with the ultimate goal of providing a tool that can be used to test the viability of EGS in the United States and worldwide. Reliable reservoir performance predictions of EGS systems require accurate and robust modeling for the coupled thermal-hydrological-mechanical processes. Conventionally, these types of problems are solved using operator-splitting methods, usually by coupling a subsurface flow and heat transport simulatormore » with a solid mechanics simulator via input files. FALCON eliminates the need for using operator-splitting methods to simulate these systems, and the scalability of the underlying MOOSE architecture allows for simulating these tightly coupled processes at the reservoir scale, allowing for examination of the system as a whole (something the operator-splitting methodologies generally cannot do).« less

Experimental estimates of the energy budget of hydrothermal eruptions; application to 2012 Upper Te Maari eruption, New Zealand

NASA Astrophysics Data System (ADS)

Montanaro, Cristian; Scheu, Bettina; Cronin, Shane J.; Breard, Eric C. P.; Lube, Gert; Dingwell, Donald B.

2016-10-01

Sudden hydrothermal eruptions occur in many volcanic settings and may include high-energy explosive phases. Ballistics launched by such events, together with ash plumes and pyroclastic density currents, generate deadly proximal hazards. The violence of hydrothermal eruptions (or explosive power) depends on the energy available within the driving-fluids (gas or liquid), which also influences the explosive mechanisms, volumes, durations, and products of these eruptions. Experimental studies in addition to analytical modeling were used here to elucidate the fragmentation mechanism and aspects of energy balance within hydrothermal eruptions. We present results from a detailed study of recent event that occurred on the 6th of August 2012 at Upper Te Maari within the Tongariro volcanic complex (New Zealand). The eruption was triggered by a landslide from this area, which set off a rapid stepwise decompression of the hydrothermal system. Explosive blasts were directed both westward and eastward of the collapsed area, with a vertical ash plume sourced from an adjacent existing crater. All explosions ejected blocks on ballistic trajectories, hundreds of which impacted New Zealand's most popular hiking trail and a mountain lodge, 1.4 km from the explosion locus. We have employed rocks representative of the eruption source area to perform rapid decompression experiments under controlled laboratory conditions that mimic hydrothermal explosions under controlled laboratory conditions. An experimental apparatus for 34 by 70 mm cylindrical samples was built to reduce the influence of large lithic enclaves (up to 30 mm in diameter) within the rock. The experiments were conducted in a temperature range of 250 °C-300 °C and applied pressure between 4 MPa and 6.5 MPa, which span the range of expected conditions below the Te Maari crater. Within this range we tested rapid decompression of pre-saturated samples from both liquid-dominated conditions and the vapor-dominated field. Further, we tested dry samples at the same pressure and temperature conditions. Results showed that host rock lithology and state of the interstitial fluid was a major influence on the fragmentation and ejection processes, as well as the energy partitioning. Clasts were ejected with velocities of up to 160 m/s as recorded by high-speed camera. In addition to rare large clasts (analogous to ballistics), a large amount of fine and very fine (<63 μm) ash was produced in all experiments. The efficiency of transformation of the total explosive energy into fragmentation energy was estimated between 10 to 15%, depending on the host rock lithology, while less than 0.1% of this was converted into kinetic energy. Our results suggest that liquid-to-vapor (flashing) expansion provides an order of magnitude higher energy release than steam expansion, which best explains the dynamics of the westward (and most energetic) directed blast at Te Maari. Considering the steam flashing as the primary energy source, the experiments suggested that a minimum explosive energy of 7 ×1010 to 2 ×1012 J was involved in the Te Maari blast. Experimental studies under controlled conditions, compared closely to a field example are thus highly useful in providing new insights into the energy release and hazards associated with eruptions in hydrothermal areas.

Biodiversity and trophic ecology of hydrothermal vent fauna associated with tubeworm assemblages on the Juan de Fuca Ridge

NASA Astrophysics Data System (ADS)

Lelièvre, Yann; Sarrazin, Jozée; Marticorena, Julien; Schaal, Gauthier; Day, Thomas; Legendre, Pierre; Hourdez, Stéphane; Matabos, Marjolaine

2018-05-01

Hydrothermal vent sites along the Juan de Fuca Ridge in the north-east Pacific host dense populations of Ridgeia piscesae tubeworms that promote habitat heterogeneity and local diversity. A detailed description of the biodiversity and community structure is needed to help understand the ecological processes that underlie the distribution and dynamics of deep-sea vent communities. Here, we assessed the composition, abundance, diversity and trophic structure of six tubeworm samples, corresponding to different successional stages, collected on the Grotto hydrothermal edifice (Main Endeavour Field, Juan de Fuca Ridge) at 2196 m depth. Including R. piscesae, a total of 36 macrofaunal taxa were identified to the species level. Although polychaetes made up the most diverse taxon, faunal densities were dominated by gastropods. Most tubeworm aggregations were numerically dominated by the gastropods Lepetodrilus fucensis and Depressigyra globulus and polychaete Amphisamytha carldarei. The highest diversities were found in tubeworm aggregations characterised by the longest tubes (18.5 ± 3.3 cm). The high biomass of grazers and high resource partitioning at a small scale illustrates the importance of the diversity of free-living microbial communities in the maintenance of food webs. Although symbiont-bearing invertebrates R. piscesae represented a large part of the total biomass, the low number of specialised predators on this potential food source suggests that its primary role lies in community structuring. Vent food webs did not appear to be organised through predator-prey relationships. For example, although trophic structure complexity increased with ecological successional stages, showing a higher number of predators in the last stages, the food web structure itself did not change across assemblages. We suggest that environmental gradients provided by the biogenic structure of tubeworm bushes generate a multitude of ecological niches and contribute to the partitioning of nutritional resources, releasing communities from competition pressure for resources and thus allowing species to coexist.

Do larvae from deep-sea hydrothermal vents disperse in surface waters?

PubMed

Yahagi, Takuya; Kayama Watanabe, Hiromi; Kojima, Shigeaki; Kano, Yasunori

2017-06-01

Larval dispersal significantly contributes to the geographic distribution, population dynamics, and evolutionary processes of animals endemic to deep-sea hydrothermal vents. Little is known as to the extent that their larvae migrate vertically to shallower waters and experience stronger currents and richer food supplies. Here, we first provide evidence from early life-history traits and population genetics for the surface dispersal of a vent species. Planktotrophic larvae of a red blood limpet, Shinkailepas myojinensis (Gastropoda: Neritimorpha: Phenacolepadidae), were cultured to observe their swimming behavior and to evaluate the effects of temperature on survival and growth. In addition, the population structure was analyzed based on 1.2-kbp mitochondrial DNA sequences from 77 specimens that cover the geographic and bathymetric distributions of the species (northwest Pacific, 442-1,227 m in depth). Hatched larvae constantly swam upward at 16.6-44.2 mm/min depending on temperature. Vertical migration from hydrothermal vents to the surface, calculated to take ~4-43 d, is attainable given their lengthy survival time without feeding. Fed larvae best survived and grew at 25°C (followed by 20°C), which approximates the sea surface temperature in the geographic range of the species. Little or no growth was observed at the temperature of the vent habitat where adult limpets occur (≤15°C). Population genetic analyses showed no differentiation among localities that are <1,350 km apart. The larvae of S. myojinensis most likely migrate to the surface water, where high phytoplankton biomass and strong currents enable their growth and long distance dispersal over many months. Sea surface temperature may represent a critical factor in determining the geographic distribution of many vent endemic species with a planktotrophic early development, and in turn the faunal composition of individual vent sites and regions. © 2017 by the Ecological Society of America.

Quantitative Characterization of Aqueous Byproducts from Hydrothermal Liquefaction of Municipal Wastes, Food Industry Wastes, and Biomass Grown on Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maddi, Balakrishna; Panisko, Ellen; Wietsma, Thomas

Hydrothermal liquefaction (HTL) is a viable thermochemical process for converting wet solid wastes into biocrude which can be hydroprocessed to liquid transportation fuel blendstocks and specialty chemicals. The aqueous byproduct from HTL contains significant amounts (20 to 50%) of the feed carbon, which must be used to enhance economic sustainability of the process on an industrial scale. In this study, aqueous fractions produced from HTL of industrial and municipal waste were characterized using a wide variety of analytical approaches. Organic chemical compounds present in these aqueous fractions were identified using two-dimensional gas chromatography equipped with time-of-flight mass spectrometry. Identified compoundsmore » include organic acids, nitrogen compounds, alcohols, aldehydes, and ketones. Conventional gas chromatography and liquid chromatography methods were employed to quantify the identified compounds. Inorganic species, in the aqueous stream of hydrothermal liquefaction of these aqueous byproducts, also were quantified using ion chromatography and inductively coupled plasma optical emission spectroscopy. The concentrations of organic chemical compounds and inorganic species are reported, and the significance of these results is discussed in detail.« less

Preparation of titanium phosphates with additives in hydrothermal process and their powder properties for cosmetics.

PubMed

Onoda, Hiroaki; Yamaguchi, Taisuke

2013-04-01

In this study, titanium phosphates were prepared from titanium chloride and phosphoric acid, sodium pyrophosphate and sodium triphosphate solutions with water retention compounds in hydrothermal process as a novel white pigment for cosmetics. Their chemical composition, powder properties, photo catalytic activity, water retention and smoothness were studied. The addition of glycerin in the preparation from sodium pyrophosphate has the useful method to obtain homogenized spherical particles of titanium phosphate pigments for the cosmetics. These titanium phosphates had less photo catalytic activity to protect the sebum on the skin. © 2012 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Investigation on structural and optical properties of ZnO film prepared by simple wet chemical method

NASA Astrophysics Data System (ADS)

Sholehah, Amalia; Mulyadi, Rendi; Haryono, Didied; Muttakin, Imamul; Rusbana, Tb Bahtiar; Mardiyanto

2018-04-01

ZnO thin layer has a broad potential application in electronic and optoelectronic devices. In this study, vertically align ZnO layers were deposited on ITO glass using wet chemistry method. The seed layers were prepared using electrodeposition technique at 3°C. The growing process was carried out using chemical bath deposition at 90°C. To improve the structural properties, two different hydrothermal treatment variations were applied separately. From the experiment, it is shown that the hydrothermal process using N2 gas has given the best result, with average diameter, crystallite size, and band-gap energy of 68.83 nm; 56.37 nm; and 3.16 eV, respectively.

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.

Analysis of the potential geochemical reactions in the Enceladus' hydrothermal environment

NASA Astrophysics Data System (ADS)

Ramirez-Cabañas, A. K.; Flandes, A.

2017-12-01

Enceladus is the sixth largest moon of Saturn and differs from its other moons, because of its cryovolcanic geysers that emanate from its south pole. The instruments of the Cassini spacecraft reveal different compounds in the gases and the dust of the geysers, such as salts (sodium chloride, sodium bicarbonate and/or sodium carbonate), as well as silica traces (Postberg et al., 2008, 2009) that could be the result of a hydrothermal environment (Hsu et al., 2014, Sekine et al., 2014). By means of a thermodynamic analysis, we propose and evaluate potential geochemical reactions that could happen from the interaction between the nucleus surface and the inner ocean of Enceladus. These reactions may well lead to the origin of the compounds found in the geysers. From this analysis, we propose that, at least, two minerals must be present in the condritic nucleus of Enceladus: olivines (fayalite and fosterite) and feldspar (orthoclase and albite). Subsequently, taking as reference the hydrothermal processes that take place on Earth, we propose the different stages of a potential hydrothermal scenario for Enceladus.

The habitat and nature of early life.

PubMed

Nisbet, E G; Sleep, N H

2001-02-22

Earth is over 4,500 million years old. Massive bombardment of the planet took place for the first 500-700 million years, and the largest impacts would have been capable of sterilizing the planet. Probably until 4,000 million years ago or later, occasional impacts might have heated the ocean over 100 degrees C. Life on Earth dates from before about 3,800 million years ago, and is likely to have gone through one or more hot-ocean 'bottlenecks'. Only hyperthermophiles (organisms optimally living in water at 80-110 degrees C) would have survived. It is possible that early life diversified near hydrothermal vents, but hypotheses that life first occupied other pre-bottleneck habitats are tenable (including transfer from Mars on ejecta from impacts there). Early hyperthermophile life, probably near hydrothermal systems, may have been non-photosynthetic, and many housekeeping proteins and biochemical processes may have an original hydrothermal heritage. The development of anoxygenic and then oxygenic photosynthesis would have allowed life to escape the hydrothermal setting. By about 3,500 million years ago, most of the principal biochemical pathways that sustain the modern biosphere had evolved, and were global in scope.

Microstructure and magnetic properties of MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn) ferrite nanocrystals prepared using colloid mill and hydrothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Wei, E-mail: wangwei@mail.buct.edu.cn; Ding, Zui; Zhao, Xiruo

2015-05-07

Three kinds of spinel ferrite nanocrystals, MFe{sub 2}O{sub 4} (M = Co, Ni, and Mn), are synthesized using colloid mill and hydrothermal method. During the synthesis process, a rapid mixing and reduction of cations with sodium borohydride (NaBH{sub 4}) take place in a colloid mill then through a hydrothermal reaction, a slow oxidation and structural transformation of the spinel ferrite nanocrystals occur. The phase purity and crystal lattice parameters are estimated by X-ray diffraction studies. Scanning electron microscopy and transmission electron microscopy images show the morphology and particle size of the as-synthesized ferrite nanocrystals. Raman spectrum reveals active phonon modesmore » at room temperature, and a shifting of the modes implies cation redistribution in the tetrahedral and octahedral sites. Magnetic measurements show that all the obtained samples exhibit higher saturation magnetization (M{sub s}). Meanwhile, experiments demonstrate that the hydrothermal reaction time has significant effects on microstructure, morphologies, and magnetic properties of the as-synthesized ferrite nanocrystals.« less

Large Marks-decahedral Pd nanoparticles synthesized by a modified hydrothermal method using a homogeneous reactor

NASA Astrophysics Data System (ADS)

Zhao, Haiqiang; Qi, Weihong; Ji, Wenhai; Wang, Tianran; Peng, Hongcheng; Wang, Qi; Jia, Yanlin; He, Jieting

2017-05-01

Fivefold symmetry appears only in small particles and quasicrystals because internal stress in the particles increases with the particle size. However, a typical Marks decahedron with five re-entrant grooves located at the ends of the twin boundaries can further reduce the strain energy. During hydrothermal synthesis, it is difficult to stir the reaction solution contained in a digestion high-pressure tank because of the relatively small size and high-temperature and high-pressure sealed environment. In this work, we optimized a hydrothermal reaction system by replacing the conventional drying oven with a homogeneous reactor to shift the original static reaction solution into a full mixing state. Large Marks-decahedral Pd nanoparticles ( 90 nm) have been successfully synthesized in the optimized hydrothermal synthesis system. Additionally, in the products, round Marks-decahedral Pd particles were also found for the first time. While it remains a challenge to understand the growth mechanism of the fivefold twinned structure, we proposed a plausible growth-mediated mechanism for Marks-decahedral Pd nanoparticles based on observations of the synthesis process.

A biographical memoir of Donald Edward White

USGS Publications Warehouse

Muffler, L. J. Patrick

2016-01-01

Donald E. White was a leading scientist for the U.S. Geological Survey, where his career was devoted almost entirely to the study of hydrothermal processes in the Earth’s crust, from the dual perspectives of active geothermal systems and of extinct hydrothermal systems now represented only by ore deposits and alteration patterns. White was devoted to analyzing the mechanisms by which ore-forming metals are concentrated, transported, and deposited. His early work on antimony deposits and on mercury transport led to the understanding that these elements, as well as some precious metals, were concentrated in hydrothermal convection systems characterized by dilute chloride waters of predominantly meteoric origin. He concluded, on the other hand, that base metals required more concentrated brines, as was impressively confirmed in the early 1960s by the discovery of the metal-rich fluids of the Salton Sea geothermal system and subsequently by the recognition of sulfide-depositing hydrothermal systems on the sea floor. His studies of active hot-spring systems elucidated the principles of geyser activity and provided the scientific foundation for research programs aimed at the understanding of geothermal systems throughout the world.

Sericitization of illite decreases sorption capabilities for cesium

NASA Astrophysics Data System (ADS)

Choung, S.; Hwang, J.; Han, W.; Shin, W.

2017-12-01

Release of radioactive cesium (137Cs) to environment occurs through nuclear accidents such as Chernobyl and Fukushima. The concern is that 137Cs has long half-life (t1/2 = 30.2 years) with chemical toxicity and γ-radiation. Sorption techniques are mainly applied to remove 137Cs from aquatic environment. In particular, it has been known well that clay minerals (e.g, illite) are effective and economical sorbents for 137Cs. Illite that was formed by hydrothermal alteration exist with sericite through "sericitization" processes. Although sericite has analogous composition and lattice structure with illite, the sorptive characteristics of illite and sericite for radiocesium could be different. This study evaluated the effects of hydrothermal alteration and weathering process on illite cesium sorption properties. Natural illite samples were collected at Yeongdong area in Korea as the world-largest hydrothermal deposits for illite. The samples were analyzed by XRF, XRD and SEM-EDX to determine mineralogy, chemical compositions and morphological characteristics, and used for batch sorption experiments. The Yeongdong illites predominantly consist of illite, sericite, quartz, and albite. The measured cesium sorption distribution coefficients (Kd,Cs) of reference illite and sericite were approximately 6000 and 400 L kg-1 at low aqueous concentration (Cw 10-7 M), respectively. In contrast, Kd,Cs values for the Yeongdong illite samples ranged from 500 to 4000 L kg-1 at identical concentration. The observed narrow and sharp XRD peak of sericite indicated that the sericite has better crystallinity compared to illite. These experimental results suggested that sericitization processes of illite can decline the sorption capabilities of illite for cesium under various hydrothermal conditions. In particular, weathering experiments raised the cesium sorption to illite, which seems to be related to the increase of preferential sorption sites for cesium through crystallinity destruction (i.e., frayed edge sites).

Kinetic Fractionation of Stable Isotopes in Carbonates on Mars: Terrestrial Analogs

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Gibson, Everett K., Jr.; Golden, D. C.; Ming, Douglas W.; McKay, Gordon A.

2003-01-01

An ancient Martian hydrosphere consisting of an alkali-rich ocean would likely produce solid carbonate minerals through the processes of evaporation and/or freezing. We postulate that both (or either) of these kinetically-driven processes would produce carbonate minerals whose stable isotopic compositions are highly fractionated (enriched) with respect to the source carbon. Various scenarios have been proposed for carbonate formation on Mars, including high temperature formation, hydrothermal alteration, precipitation from evaporating brines, and cryogenic formation. 13C and 18O -fractionated carbonates have previously been shown to form kinetically under some of these conditions, ie.: 1) alteration by hydrothermal processes, 2) low temperature precipitation (sedimentary) from evaporating bicarbonate (brine) solutions, and 3) precipitation during the process of cryogenic freezing of bicarbonate-rich fluids. Here we examine several terrestrial field settings within the context of kinetically controlled carbonate precipitation where stable isotope enrichments have been observed.

Hydrothermal liquefaction pathways for low-nitrogen biocrude from wet algae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanzella, Francis; Lim, Jin-Ping

Our SRI International (SRI) team has developed a new two-step hydrothermal liquefaction (HTL) process to convert wet algal biomass into biocrude oil. The first step in the process (low-temperature HTL or HTL1) yields crude oil but, most importantly, it selectively dissolves nitrogen-containing compounds in the aqueous phase. Once the oil and the aqueous phase are separated, the low-nitrogen soft solids left behind can be taken to the second step (high-temperature HTL or HTL2) for full conversion to biocrude. HTL2 will hence yield low-nitrogen biocrude, which can be hydro-processed to yield transportation fuels. The expected high carbon yield and low nitrogenmore » content can lead to a transportation fuel from algae that avoids two problems common to existing algae-to-fuel processes: (1) poisoning of the hydro-processing catalyst; and (2) inefficient conversion of algae-to-liquid fuels. The process we studied would yield a new route to strategic energy production from domestic sources.« less

Sources and fractionation processes influencing the isotopic distribution of H, O and C in the Long Valley hydrothermal system, California, U.S.A.

USGS Publications Warehouse

White, A.F.; Peterson, M.L.; Wollenberg, H.; Flexser, S.

1990-01-01

The isotopic ratios of H, O and C in water within the Long Valley caldera, California reflect input from sources external to the hydrothermal reservoir. A decrease in ??D in precipitation of 0.5??? km-1, from west to east across Long Valley, is caused by the introduction of less fractionated marine moisture through a low elevation embayment in the Sierra Nevada Mountain Range. Relative to seasonal fluctuations in precipitation (-158 to -35??.), ??D ranges in hot and cold surface and groundwaters are much less variable (-135 to -105??.). Only winter and spring moisture, reflecting higher precipitation rates with lighter isotopic signatures, recharge the hydrological system. The hydrothermal fluids are mixtures of isotopically heavy recharge (??D = - 115???, ??18O = - 15???) derived from the Mammoth embayment, and isotopically lighter cold water (??D = -135???, ??18O = -18???). This cold water is not representative of current local recharge. The ??13C values for dissolved carbon in hot water are significantly heavier (- 7 to - 3???) than in cold water (-18 to -10???) denoting a separate hydrothermal origin. These ??13C values overlie the range generally attributed to magmatic degassing of CO2. However, ??13C values of metamorphosed Paleozoic basement carbonates surrounding Long Valley fall in a similar range, indicating that hydrothermal decarbonization reactions are a probable source of CO2. The ??13C and ??18O values of secondary travertime and vein calcite indicate respective fractionation with CO2 and H2O at temperatures approximating current hydrothermal conditions. ?? 1990.

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Structural controls on hydrothermal alteration and ore mineralization

USGS Publications Warehouse

Berger, Byron R.; Henley, Richard W.

2011-01-01

High-sulfidation copper–gold lode deposits such as Chinkuashih, Taiwan, Lepanto, Philippines, and Goldfield, Nevada, formed within 1500 m of the paleosurface in volcanic terranes. All underwent an early stage of extensive advanced argillic silica–alunite alteration followed by an abrupt change to spatially much more restricted stages of fracture-controlled sulfide–sulfosalt mineral assemblages and gold–silver mineralization. The alteration as well as ore mineralization stages of these deposits were controlled by the dynamics and history of syn-hydrothermal faulting.At the Sulfate Stage, aggressive advanced argillic alteration and silicification were consequent on the in situ formation of acidic condensate from magmatic vapor as it expanded through secondary fracture networks alongside active faults. The reduction of permeability at this stage due to alteration decreased fluid flow to the surface, and progressively developed a barrier between magmatic-vapor expansion constrained by the active faults and peripheral hydrothermal activity dominated by hot-water flow. In conjunction with the increased rock strength resulting from alteration, subsequent fault-slip inversion in response to an increase in compressional stress generated new, highly permeable fractures localized by the embrittled, altered rock. The new fractures focused magmatic-vapor expansion with much lower heat loss so that condensation occurred. Sulfide Stage sulfosalt, sulfide, and gold–silver deposition then resulted from destabilization of vapor phase metal species due to vapor decompression through the new fracture array. The switch from sulfate to sulfide assemblages is, therefore, a logical consequence of changes in structural permeability due to the coupling of alteration and fracture dynamics rather than to changes in the chemistry of the fluid phase at its magmatic source.

Extensive genome rearrangements and multiple horizontal gene transfers in a population of pyrococcus isolates from Vulcano Island, Italy.

PubMed

White, James R; Escobar-Paramo, Patricia; Mongodin, Emmanuel F; Nelson, Karen E; DiRuggiero, Jocelyne

2008-10-01

The extent of chromosome rearrangements in Pyrococcus isolates from marine hydrothermal vents in Vulcano Island, Italy, was evaluated by high-throughput genomic methods. The results illustrate the dynamic nature of the genomes of the genus Pyrococcus and raise the possibility of a connection between rapidly changing environmental conditions and adaptive genomic properties.

Discriminating fluid source regions in orogenic gold deposits using B-isotopes

NASA Astrophysics Data System (ADS)

Lambert-Smith, James S.; Rocholl, Alexander; Treloar, Peter J.; Lawrence, David M.

2016-12-01

The genesis of orogenic gold deposits is commonly linked to hydrothermal ore fluids derived from metamorphic devolatilization reactions. However, there is considerable debate as to the ultimate source of these fluids and the metals they transport. Tourmaline is a common gangue mineral in orogenic gold deposits. It is stable over a very wide P-T range, demonstrates limited volume diffusion of major and trace elements and is the main host of B in most rock types. We have used texturally resolved B-isotope analysis by secondary ion mass spectrometry (SIMS) to identify multiple fluid sources within a single orogenic gold ore district. The Loulo Mining District in Mali, West Africa hosts several large orogenic gold ore bodies with complex fluid chemistry, associated with widespread pre-ore Na- and multi-stage B-metasomatism. The Gara deposit, as well as several smaller satellites, formed through partial mixing between a dilute aqueous-carbonic fluid and a hypersaline brine. Hydrothermal tourmaline occurs as a pre-ore phase in the matrix of tourmalinite units, which host mineralization in several ore bodies. Clasts of these tourmalinites occur in mineralized breccias. Disseminated hydrothermal and vein hosted tourmaline occur in textural sites which suggest growth during and after ore formation. Tourmalines show a large range in δ11B values from -3.5 to 19.8‰, which record a change in fluid source between paragenetic stages of tourmaline growth. Pre-mineralization tourmaline crystals show heavy δ11B values (8-19.8‰) and high X-site occupancy (Na ± Ca; 0.69-1 apfu) suggesting a marine evaporite source for hydrothermal fluids. Syn-mineralization and replacement phases show lighter δ11B values (-3.5 to 15.1‰) and lower X-site occupancy (0.62-0.88 apfu), suggesting a subsequent influx of more dilute fluids derived from devolatilization of marine carbonates and clastic metasediments. The large, overlapping range in isotopic compositions and a skew toward the opposing population in the δ11B data for both tourmaline groups reflects continual tourmaline growth throughout mineralization, which records the process of fluid mixing. A peak in δ11B values at ∼8‰ largely controlled by tourmalines of syn- to post-ore timing represents a mixture of the two isotopically distinct fluids. This paper demonstrates that B-isotopes in tourmaline can be instrumental in interpreting complex and dynamic hydrothermal systems. The importance of B as an integral constituent of orogenic ore forming fluids and as a gangue phase in orogenic gold deposits makes B-isotope analysis a powerful tool for testing the level of source region variability in these fluids, and by extension, that of metal sources.

Metal mobilisation in hydrothermal sediments at the TAG Hydrothermal Field (MAR, 26°N)

NASA Astrophysics Data System (ADS)

Dutrieux, A. M.; Lichtschlag, A.; Martins, S.; Barriga, F. J.; Petersen, S.; Murton, B. J.

2017-12-01

Metalliferous sediments in the vicinity of hydrothermal systems are enriched in base metals, but few studies have addressed their potential as mineral resources. These metalliferous sediments have been accumulated by different processes and reflect modifications of the primary mineral deposits by: oxidation of the chimney materials, in situ precipitation of low-temperature minerals and mass wasting. To understand the post-formation processes in metalliferous sediments, we investigated sub-seafloor metal mobilisation in different geological environments. This presentation focuses on the TAG Hydrothermal Field (Mid-Atlantic Ridge, 26°N) and explores sediment and pore water compositions using ICP-MS and ICP-OES. We use reactive transport modelling to interpret the degree of metal remobilisation and to identify the most important geochemical reactions in the different sediments. The pore water concentrations measured in sediments above inactive sulphide mounds present constant major elements composition that indicates this environment is dominated by complete exchange with seawater. The sediments, that are mainly composed of hematite and goethite formed during the oxidation of sulphides, have low Cu concentrations (< 0.1%) and the main part of their primary Cu and Zn content has likely been mobilized. Cu concentrations increase at the edges of the mounds (up to wt. 20%) or in distal depositionary channels (up to wt.10%) where sulphide minerals (e.g. pyrite, chalcopyrite and sphalerite) are still present in the sediments and capped by more recent sediment slumping. In the depositionary channels, pore waters show metal concentrations affected by diagenesis and redox-sensitive metals are released at depth (e.g. Mn2+ and Cu2+). The leaching of the primary sulphides (e.g. deprecated grains of chalcopyrite), and metal mobilisation lead to an enrichment of Cu and Zn at shallower depth. Here, some stratigraphic horizons scavenge metallic cations back into solid phases and form Mn-oxide crusts between 30 and 60 cm, in which Cu concentrations also increase. Our results demonstrate that metal mobilisation differs depending on the geological environment and their related accumulation processes, causing the absence of Cu on the top of inactive hydrothermal mounds but enriched in more distal sediment basins.

Batch bioethanol production via the biological and chemical saccharification of some Egyptian marine macroalgae.

PubMed

Soliman, Ramadan M; Younis, Sherif A; El-Gendy, Nour Sh; Mostafa, Soha S M; El-Temtamy, Seham A; Hashim, Ahmed I

2018-04-19

Marine seaweeds (macroalgae) cause eutrophication problem and affects the touristic activities. The success of the production of the third generation bioethanol from marine macroalgae depends mainly on the development of an ecofriendly and eco-feasible pretreatment (i.e. hydrolysis) technique, a highly effective saccharification step and finally an efficient bioethanol fermentation step. Therefore, this study aimed to investigate the potentiality of different marine macroalgal strains, collected from Egyptian coasts, for bioethanol production via different saccharification processes. Different marine macroalgal strains; red Jania rubens, green Ulva lactuca. and brown Sargassum latifolium, have been collected from Egyptian Mediterranean and Red Sea shores. Different hydrolysis processes were evaluated to maximize the extraction of fermentable sugars; thermo-chemical hydrolysis with diluted acids (HCl and H 2 SO 4 ) and base (NaOH), hydrothermal hydrolysis followed by saccharification with different fungal strains and finally, thermo-chemical hydrolysis with diluted HCl, followed by fungal saccharification. The hydrothermal hydrolysis of Sargassum latifolium followed by biological saccharification using Trichoderma asperellum RM1 produced maximum total sugars of 510 mg g -1 macroalgal biomass. The integration of the hydrothermal and fungal hydrolyses of the macroalgal biomass with a separate batch fermentation of the produced sugars using two Saccharomyces cerevisiae strains, produced approximately 0.29 g bioethanol g -1 total reducing sugars. A simulated regression modeling for the batch bioethanol fermentation was also performed. This study, supported the possibility of using seaweeds as a renewable source of bioethanol, throughout a suggested integration of macroalgal biomass hydrothermal- and fungal- hydrolysis with a separate batch bioethanol fermentation process of the produced sugars. The usage of marine macroalgae (i.e. seaweeds) as feedstock for bioethanol; an alternative and/or complimentary to petro-fuel, would act as triple fact solution; bioremediation process for ecosystem, renewable energy source and economy savings. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Physicochemical properties of hydrothermally treated peat fuel obtained from Mempawah-West Kalimantan: influence of hydrophilicity index on carbon aromaticity and combustibility

NASA Astrophysics Data System (ADS)

Mursito, Anggoro Tri; Hirajima, T.; Listiyowati, L. N.

2018-02-01

Mempawah peat of West Kalimantan was selected as raw material for studying the physicochemical properties of peat fuel products and their characteristic in the hydrothermal upgrading process at a temperature range of 150°C to 380°C at an average heating rate of 6.6°C/min for 30 minutes. The 13C NMR spectra revealed changes in the effect of temperature on carbon aromaticity of raw peat and peat fuel products which were in 0.39 to 0.63 as the temperature increased. Other phenomenon occurring during the experiment was hydrophilicity index of peat fuel surface decreases of about 1.7 and 1.4 with increased treatment temperature. We also found that hydrothermal upgrading also affected the combustion properties of peat fuel products. Ignition temperature of raw peat and solid products were at 175°C and between 188°C to 285°C respectively. Temperature at the maximum combustion rate of raw peat and solid products was at 460°C, and between 477°C to 509°C were suggested to the increasing of reactivity of solid products respectively. Here, we discussed several phenomenon of the peat fuel product during hydrothermal process with a respect to the change in the physicochemical properties as determined by Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric and Differential Thermal Analysis (TG-DTA) analyses, 13C NMR and also other supporting analytical equipment.

Influence of TiCl4 precursor in hydrothermal synthesis of TiO2 nanostructures

NASA Astrophysics Data System (ADS)

Kartikay, Purnendu; Nemala, Siva Sankar; Mallick, Sudhanshu

2017-05-01

Rutile TiO2 films were deposited on the FTO substrate by the hydrothermal process using TTIP and TiCl4 as the titania precursor. Our study manifestly exhibits the influence of TiCl4 precursor on the hydrothermal growth of the TiO2 structure. The morphology of prepared film varies from nano-cauliflower to nano-flower to nano-parallelepiped rod-like structure with the addition of TiCl4 as the precursor. When TiCl4 is introduced in the precursor HCl corresponding to four times of the Ti4+ concentration is generated as a by-product during the reaction, these additional HCl promotes the etching of the nanostructure enabling the nanostructure to unfurl. We conclude that the tailoring of the nanostructure can be performed by addition of TiCl4 in the precursor

Hydrothermal diamond anvil cell for XAFS studies of first-row transition elements in aqueous solutions up to supercritical conditions

USGS Publications Warehouse

Bassett, William A.; Anderson, Alan J.; Mayanovic, Robert A.; Chou, I.-Ming

2000-01-01

A hydrothermal diamond anvil cell (HDAC) has been modified by drilling holes with a laser to within 150 ??m of the anvil face to minimize the loss of X-rays due to absorption and scatter by diamond. This modification enables acquisition of K-edge X-ray absorption fine structure (XAFS) spectra from first-row transition metal ions in aqueous solutions at temperatures ranging from 25??C to 660??C and pressures up to 800 MPa. These pressure-temperature (P-T) conditions are more than sufficient for carrying out experimental measurements that can provide data valuable in the interpretation of fluid inclusions in minerals found in ore-forming hydrothermal systems as well as other important lithospheric processes involving water. (C) 2000 Elsevier Science B.V. All rights reserved.

Major components of seawater and hydrothermal plumes in the Okinawa Trough, East China Sea, and Yellow Sea

NASA Astrophysics Data System (ADS)

Zeng, Z.; Rong, K.; Chen, C. T. A.; Wang, X.; Qi, H.

2017-12-01

Analyses of the major components of seawater and hydrothermal plumes in hydrothermal fields are essential for an improved understanding of ocean carbonate system, element solubility and redox reactions (e.g., iron and copper). The composition of major components in seawater and hydrothermal plume samples from 118 stations have been investigated in the Okinawa Trough (OT), East China Sea (ECS), and Yellow Sea (YS). At least seven water masses take part in the mixing processes: the Kuroshio water, OT water, ECS water, YS water, Taiwan Strait water, vent fluid and hydrothermal plume water. About 6 - 16 % of the plume water comes from the Kuroshio deep water, 50 - 64% of the hydrothermal plume water comes from the vent fluid in the wet and dry season. In addition, the calculated SHVF (36 and 36.8) and SHPW (35 and 35.8) values are higher than the measured salinity values (34.4) of hydrothermal plumes in the OT. Major elements exhibit linear correlation in seawater (e.g., B3+ and Sr2+) of the OT, the ECS, and the YS. Element ratios (e.g., Sr/Ca, Ca/Cl) in OT water column are similar to that in average seawater, indicating that Sr/Ca and Ca/Cl ratios might be a useful proxy for chemical properties of seawater. Furthermore, from the southern and middle OT to the northern OT, ECS, and YS, the salinity, potential density, Cl/salinity ratio of seawater tend to decrease. The positive correlations between major components (e.g., SO42-, Cl-), physical properties (e.g., salinity, temperature, potential density) and current (velocity) in the seawater column suggests that the physical and chemical properties of seawater in the OT are affected by input of the Kuroshio current. In the Iheya North knoll, Clam, Yonaguni Knoll IV, and Tangyin hydrothermal fields of the OT, anomalous layers of seawater in the water column have higher Ca/SO42-, Mn/Mg ratios and higher optical anomalies than other layers, suggesting that the chemical variations of hydrothermal plumes result in the discharge of high Ca2+ and low Mg2+ fluid. The Ca2+and Mn2+ flux to seawater in the OT is about 1.04-326 and 1.30-76.4 ×1012 kg per year, respectively. The heat flux is about 0.159-1,973 ×105 W, which means that roughly 0.0006 % of ocean heat is supplied by seafloor hydrothermal plumes in the OT.

Hydrothermal Alteration of the Lower Oceanic Crust: Insight from OmanDP Holes GT1A and GT2A.

NASA Astrophysics Data System (ADS)

Harris, M.; Zihlmann, B.; Mock, D.; Akitou, T.; Teagle, D. A. H.; Kondo, K.; Deans, J. R.; Crispini, L.; Takazawa, E.; Coggon, J. A.; Kelemen, P. B.

2017-12-01

Hydrothermal circulation is a fundamental Earth process that is responsible for the cooling of newly formed ocean crust at mid ocean ridges and imparts a chemical signature on both the crust and the oceans. Despite decades of study, the critical samples necessary to resolve the role of hydrothermal circulation during the formation of the lower ocean crust have remained poorly sampled in the ocean basins. The Oman Drilling Project successfully cored 3 boreholes into the lower crust of the Semail ophiolite (Holes GT1A layered gabbros, GT2A foliated gabbros and GT3A dike/gabbro transition). These boreholes have exceptionally high recovery ( 100%) compared to rotary coring in the oceans and provide an unrivalled opportunity to quantitatively characterise the hydrothermal system in the lower oceanic crust. Hydrothermal alteration in Holes GT1A and GT2A is ubiquitous and manifests as secondary minerals replacing primary igneous phases and secondary minerals precipitated in hydrothermal veins and hydrothermal fault zones. Hole GT1A is characterised by total alteration intensities between 10 -100%, with a mean alteration intensity of 60%, and shows no overall trend downhole. However, there are discrete depth intervals (on the scale of 30 -100 m) where the total alteration intensity increases with depth. Alteration assemblages are dominated by chlorite + albite + amphibole, with variable abundances of epidote, clinozoisite and quartz. Hole GT1A intersected several hydrothermal fault zones, these range from 2-3 cm up to >1m in size and are associated with more complex secondary mineral assemblages. Hydrothermal veins are abundant throughout Hole GT1A, with a mean density of 37 vein/m. Hole GT2A is characterised by total alteration intensities between 6-100%, with a mean alteration intensity of 45%, and is highly variable downhole. Alteration halos and patches are slightly more abundant than in Hole GT1A. The secondary mineral assemblage is similar to Hole GT1A, but Hole GT2A has higher abundances of epidote, clinozoisite, quartz, laumontite and iron-oxydroxides. Vein density in Hole GT2A is 61 veins/m. In both holes, cross cutting vein relationships indicate a relative timing from earliest to latest of: amphibole; epidote + zoisite + qtz; chlorite + prehnite + qtz, calcite-laumontite-anhydrite; gypsum.

Synthesis and Characterization of Antireflective ZnO Nanoparticles Coatings Used for Energy Improving Efficiency of Silicone Solar Cells

NASA Astrophysics Data System (ADS)

Pîslaru-Dănescu, Lucian; Chitanu, Elena; El-Leathey, Lucia-Andreea; Marinescu, Virgil; Marin, Dorian; Sbârcea, Beatrice-Gabriela

2018-05-01

The paper proposes a new and complex process for the synthesis of ZnO nanoparticles for antireflective coating corresponding to silicone solar cells applications. The process consists of two major steps: preparation of seed layer and hydrothermal growth of ZnO nanoparticles. Due to the fact that the seed layer morphology influences the ZnO nanoparticles proprieties, the process optimization of the seed layer preparation is necessary. Following the hydrothermal growth of the ZnO nanoparticles, antireflective coating of silicone solar cells is achieved. After determining the functional parameters of the solar cells provided either with glass or with ZnO, it is concluded that all the parameters values are superior in the case of solar cells with ZnO antireflection coating and are increasing along with the solar irradiance.

Mineralization of Alvinella polychaete tubes at hydrothermal vents.

PubMed

Georgieva, M N; Little, C T S; Ball, A D; Glover, A G

2015-03-01

Alvinellid polychaete worms form multilayered organic tubes in the hottest and most rapidly growing areas of deep-sea hydrothermal vent chimneys. Over short periods of time, these tubes can become entirely mineralized within this environment. Documenting the nature of this process in terms of the stages of mineralization, as well as the mineral textures and end products that result, is essential for our understanding of the fossilization of polychaetes at hydrothermal vents. Here, we report in detail the full mineralization of Alvinella spp. tubes collected from the East Pacific Rise, determined through the use of a wide range of imaging and analytical techniques. We propose a new model for tube mineralization, whereby mineralization begins as templating of tube layer and sublayer surfaces and results in fully mineralized tubes comprised of multiple concentric, colloform, pyrite bands. Silica appeared to preserve organic tube layers in some samples. Fine-scale features such as protein fibres, extracellular polymeric substances and two types of filamentous microbial colonies were also found to be well preserved within a subset of the tubes. The fully mineralized Alvinella spp. tubes do not closely resemble known ancient hydrothermal vent tube fossils, corroborating molecular evidence suggesting that the alvinellids are a relatively recent polychaete lineage. We also compare pyrite and silica preservation of organic tissues within hydrothermal vents to soft tissue preservation in sediments and hot springs. © 2014 The Authors. Geobiology Published by John Wiley & Sons Ltd.

Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

2008-01-01

The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

Mineralogy and Geochemistry of Vanadium-Bearing Black Shales at Zhangcun and Zhengfang, Eastern Jiangxi Province, China

NASA Astrophysics Data System (ADS)

Long, H.; Long, H.; Nekvasil, H.; Liu, Y.

2001-12-01

As a member of Hetang Formation, lower Cambrian, the Zhangcun-Zhengfang vanadium-bearing black shales are spread in the sea basin outside of the Ancient Jiangnan Island Arc. The composition of black shales is silicalite + siltstone + detrital carbonate. A large amount of hyalophane has been discovered in the shales and the hyalophane-rich rock is the major type of vanadium-host rock. The barium content in the hyalophane is up to 18.91%. The vanadium mainly exists in vanadiferous illite and several Ti-V oxides, possibly including a new mineral. The chemical formula of this kind of Ti-V oxide is V2O3¡nTiO2, n=4¡ª9, according to the electronic microprobe studies. The micro X-ray diffraction studies show the new mineral may be triclinic. The shales are rich in Ba, K, V and contain only trace Na and Mn while all the compositions of the shales except carbonate have a low content of Mg and Ca. According to the authors¡_ study, V obviously has a relationship with Ba and Se, which are from the volcano or hydrothermal activities, and the basic elements Cr, Co, Ni, Ti and Fe. It may present that they are from the same source. Thus, it seems that they are not from the ¡rnormal¡_ sedimentary environment and may be from the hydrothermal deposition. The REE models show that silicalite may be the hydrothermal deposit that does not mix with seawater while the REE models of hyalopahne-rich rock is similar to some modern hydrothermal deposits in the seafloor. The subtle negative anomaly of Yb may reflect the REE model of basalt in the seafloor. The geology and geochemistry of the shales indicate that the shales may be of hydrothermal genesis. Silicalite may be the typical ¡r pure¡_ hydrothermal sediment and hyalophane-rich rock may be the product of hydrothermal activity while the hydrothermal fluid passes the continent source material in the sedimentary process. V, Ti, Ba and Si may be from the volcanic rock in the seafloor and the Al and K may be from the continent.

Integrated Fe- and S-isotope study of seafloor hydrothermal vents at East Pacific Rise 9-10°N

USGS Publications Warehouse

Rouxel, O.; Shanks, Wayne C.; Bach, W.; Edwards, K.J.

2008-01-01

In this study, we report on coupled Fe- and S-isotope systematics of hydrothermal fluids and sulfide deposits from the East Pacific Rise at 9–10°N to better constrain processes affecting Fe-isotope fractionation in hydrothermal environments. We aim to address three fundamental questions: (1) Is there significant Fe-isotope fractionation during sulfide precipitation? (2) Is there significant variability of Fe-isotope composition of the hydrothermal fluids reflecting sulfide precipitation in subsurface environments? (3) Are there any systematics between Fe- and S-isotopes in sulfide minerals? The results show that chalcopyrite, precipitating in the interior wall of a hydrothermal chimney displays a limited range of δ56Fe values and δ34S values, between − 0.11 to − 0.33‰ and 2.2 to 2.6‰ respectively. The δ56Fe values are, on average, slightly higher by 0.14‰ relative to coeval vent fluid composition while δ34S values suggest significant S-isotope fractionation (− 0.6 ± 0.2‰) during chalcopyrite precipitation. In contrast, systematically lower δ56Fe and δ34S values relative to hydrothermal fluids, by up to 0.91‰ and 2.0‰ respectively, are observed in pyrite and marcasite precipitating in the interior of active chimneys. These results suggest isotope disequilibrium in both Fe- and S-isotopes due to S-isotopic exchange between hydrothermal H2S and seawater SO42− followed by rapid formation of pyrite from FeS precursors, thus preserving the effects of a strong kinetic Fe-isotope fractionation during FeS precipitation. In contrast, δ56Fe and δ34S values of pyrite from inactive massive sulfides, which show evidence of extensive late-stage reworking, are essentially similar to the hydrothermal fluids. Multiple stages of remineralization of ancient chimney deposits at the seafloor appear to produce minimal Fe-isotope fractionation. Similar affects are indicated during subsurface sulfide precipitation as demonstrated by the lack of systematic differences between δ56Fe values in both high-temperature, Fe-rich black smokers and lower-temperature, Fe-depleted vents.

Hydrothermal Habitats: Measurements of Bulk Microbial Elemental Composition, and Models of Hydrothermal Influences on the Evolution of Dwarf Planets

NASA Astrophysics Data System (ADS)

Neveu, Marc Francois Laurent

Finding habitable worlds is a key driver of solar system exploration. Many solar system missions seek environments providing liquid water, energy, and nutrients, the three ingredients necessary to sustain life. Such environments include hydrothermal systems, spatially-confined systems where hot aqueous fluid circulates through rock by convection. I sought to characterize hydrothermal microbial communities, collected in hot spring sediments and mats at Yellowstone National Park, USA, by measuring their bulk elemental composition. To do so, one must minimize the contribution of non-biological material to the samples analyzed. I demonstrate that this can be achieved using a separation method that takes advantage of the density contrast between cells and sediment and preserves cellular elemental contents. Using this method, I show that in spite of the tremendous physical, chemical, and taxonomic diversity of Yellowstone hot springs, the composition of microorganisms there is surprisingly ordinary. This suggests the existence of a stoichiometric envelope common to all life as we know it. Thus, future planetary investigations could use elemental fingerprints to assess the astrobiological potential of hydrothermal settings beyond Earth. Indeed, hydrothermal activity may be widespread in the solar system. Most solar system worlds larger than 200 km in radius are dwarf planets, likely composed of an icy, cometary mantle surrounding a rocky, chondritic core. I enhance a dwarf planet evolution code, including the effects of core fracturing and hydrothermal circulation, to demonstrate that dwarf planets likely have undergone extensive water-rock interaction. This supports observations of aqueous products on their surfaces. I simulate the alteration of chondritic rock by pure water or cometary fluid to show that aqueous alteration feeds back on geophysical evolution: it modifies the fluid antifreeze content, affecting its persistence over geological timescales; and the distribution of radionuclides, whose decay is a chief heat source on dwarf planets. Interaction products can be observed if transported to the surface. I simulate numerically how cryovolcanic transport is enabled by primordial and hydrothermal volatile exsolution. Cryovolcanism seems plausible on dwarf planets in light of images recently returned by spacecrafts. Thus, these coupled geophysical-geochemical models provide a comprehensive picture of dwarf planet evolution, processes, and habitability.

The clumped-isotope geochemistry of exhumed marbles from Naxos, Greece

NASA Astrophysics Data System (ADS)

Ryb, U.; Lloyd, M. K.; Stolper, D. A.; Eiler, J. M.

2017-07-01

Exhumation and accompanying retrograde metamorphism alter the compositions and textures of metamorphic rocks through deformation, mineral-mineral reactions, water-rock reactions, and diffusion-controlled intra- and inter-mineral atomic mobility. Here, we demonstrate that these processes are recorded in the clumped- and single-isotope (δ13 C and δ18 O) compositions of marbles, which can be used to constrain retrograde metamorphic histories. We collected 27 calcite and dolomite marbles along a transect from the rim to the center of the metamorphic core-complex of Naxos (Greece), and analyzed their carbonate single- and clumped-isotope compositions. The majority of Δ47 values of whole-rock samples are consistent with exhumation- controlled cooling of the metamorphic complex. However, the data also reveal that water-rock interaction, deformation driven recrystallization and thermal shock associated with hydrothermal alteration may considerably impact the overall distribution of Δ47 values. We analyzed specific carbonate fabrics influenced by deformation and fluid-rock reaction to study how these processes register in the carbonate clumped-isotope system. Δ47 values of domains drilled from a calcite marble show a bimodal distribution. Low Δ47 values correspond to an apparent temperature of 260 °C and are common in static fabrics; high Δ47 values correspond to an apparent temperature of 200 °C and are common in dynamically recrystallized fabrics. We suggest that the low Δ47 values reflect diffusion-controlled isotopic reordering during cooling, whereas high Δ47 values reflect isotopic reordering driven by dynamic recrystallization. We further studied the mechanism by which dynamic recrystallization may alter Δ47 values by controlled heating experiments. Results show no significant difference between laboratory reactions rates in the static and dynamic fabrics, consistent with a mineral-extrinsic mechanism, in which slip along crystal planes was associated with atomic-scale isotopic reordering in the calcite lattice. An intrinsic mechanism (enhanced isotopic reordering rate in deformed minerals) is contraindicated by these experiments. We suggest that Δ47 values of dynamically recrystallized fabrics that form below the diffusion-controlled blocking-temperature for calcite constrain the temperature of deformation. We find that Δ47-based temperatures of static fabrics from Naxos marbles are ∼60-80 °C higher than commonly observed in slowly cooled metamorphic rocks, and would suggest cooling rates of ∼105 °CMyr-1. A similar thermal history is inferred for dolomite marbles from the core vicinity, which preserve apparent temperatures up to 200 °C higher than a typical blocking temperature (∼300 °C). This finding could be explained by a hydrothermal event driving a brief thermal pulse and locally resetting Δ47 values. Rapid cooling of the core-complex region is consistent with a compilation of published cooling ages and a new apatite U-Th/He age, associating the thermal event with the emplacement of a granodiorite pluton at ∼12 Ma.

Insight from Genomics on Biogeochemical Cycles in a Shallow-Sea Hydrothermal System

NASA Astrophysics Data System (ADS)

Lu, G. S.; Amend, J.

2015-12-01

Shallow-sea hydrothermal ecosystems are dynamic, high-energy systems influenced by sunlight and geothermal activity. They provide accessible opportunities for investigating thermophilic microbial biogeochemical cycles. In this study, we report biogeochemical data from a shallow-sea hydrothermal system offshore Paleochori Bay, Milos, Greece, which is characterized by a central vent covered by white microbial mats with hydrothermally influenced sediments extending into nearby sea grass area. Geochemical analysis and deep sequencing provide high-resolution information on the geochemical patterns, microbial diversity and metabolic potential in a two-meter transect. The venting fluid is elevated in temperature (~70oC), low in pH (~4), and enriched in reduced species. The geochemical pattern shows that the profile is affected by not only seawater dilution but also microbial regulation. The microbial community in the deepest section of vent core (10-12 cm) is largely dominated by thermophilic archaea, including a methanogen and a recently described Crenarcheon. Mid-core (6-8 cm), the microbial community in the venting area switches to the hydrogen utilizer Aquificae. Near the sediment-water interface, anaerobic Firmicutes and Actinobacteria dominate, both of which are commonly associated with subsurface and hydrothermal sites. All other samples are dominated by diverse Proteobacteria. The sulfate profile is strongly correlated with the population size of delta- and episilon-proteobactia. The dramatic decrease in concentrations of As and Mn in pore fluids as a function of distance from the vent suggests that in addition to seawater dilution, microorganisms are likely transforming these and other ions through a combination of detoxification and catabolism. In addition, high concentrations of dissolved Fe are only measurable in the shallow sea grass area, suggesting that iron-transforming microorganisms are controlling Fe mobility, and promoting biomineralization. Taken together, these samples represent the effects of submarine venting on sediment microbial communities both vertically and horizontally in the predicted fluid flow path, and will provide a detailed investigation of genetic potential for biogeochemical cycling at Paleochori Bay.

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Daly, Paul; van Munster, Jolanda M.; Blythe, Martin J.

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retainingmore » more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.« less

Expression of Aspergillus niger CAZymes is determined by compositional changes in wheat straw generated by hydrothermal or ionic liquid pretreatments

DOE PAGES

Daly, Paul; van Munster, Jolanda M.; Blythe, Martin J.; ...

2017-02-07

The capacity of fungi, such as Aspergillus niger, to degrade lignocellulose is harnessed in biotechnology to generate biofuels and high-value compounds from renewable feedstocks. Most feedstocks are currently pretreated to increase enzymatic digestibility: improving our understanding of the transcriptomic responses of fungi to pretreated lignocellulosic substrates could help to improve the mix of activities and reduce the production costs of commercial lignocellulose saccharifying cocktails. We investigated the responses of A. niger to untreated, ionic liquid and hydrothermally pretreated wheat straw over a 5-day time course using RNA-seq and targeted proteomics. The ionic liquid pretreatment altered the cellulose crystallinity while retainingmore » more of the hemicellulosic sugars than the hydrothermal pretreatment. Ionic liquid pretreatment of straw led to a dynamic induction and repression of genes, which was correlated with the higher levels of pentose sugars saccharified from the ionic liquid-pretreated straw. Hydrothermal pretreatment of straw led to reduced levels of transcripts of genes encoding carbohydrate-active enzymes as well as the derived proteins and enzyme activities. Both pretreatments abolished the expression of a large set of genes encoding pectinolytic enzymes. These reduced levels could be explained by the removal of parts of the lignocellulose by the hydrothermal pretreatment. The time course also facilitated identification of temporally limited gene induction patterns. The presented transcriptomic and biochemical datasets demonstrate that pretreatments caused modifications of the lignocellulose, to both specific structural features as well as the organisation of the overall lignocellulosic structure, that determined A. niger transcript levels. The experimental setup allowed reliable detection of substrate-specific gene expression patterns as well as hitherto non-expressed genes. Our data suggest beneficial effects of using untreated and IL-pretreated straw, but not HT-pretreated straw, as feedstock for CAZyme production.« less

3-D Resistivity Structure of La Soufrière Volcano (Guadeloupe): New Insights into the Hydrothermal System and Associated Hazards

NASA Astrophysics Data System (ADS)

Rosas-Carbajal, M.; Nicollin, F.; Komorowski, J. C.; Gibert, D.; Deroussi, S.

2015-12-01

The 3-D electrical resistivity model of the dome of La Soufrière of Guadeloupe volcano was obtained by inverting more than 23000 electrical resistivity tomography (ERT) and mise-a-la-masse data points. Data acquisition involved 2-D and 3-D protocols, including several pairs of injection electrodes located on opposite sides of the volcano. For the mise-a-la-masse measurements, the contact with a conductive mass was achieved by immersing one of the current electrodes in the Tarissan acid pond (~25 Siemens/m) located in the volcano's summit. The 3-D inversion was performed using a deterministic smoothness-constrained least-squares algorithm with unstructured grid modeling to accurately account for topography. Resistivity contrasts of more than 4 orders of magnitude are observed. A thick and high-angle conductive structure is located in the volcano's southern flank. It extends from the Tarissan Crater's acid pond on the summit to a hot spring region located close to the dome's southern base. This suggests that a large hydrothermal reservoir is located below the southern base of the dome, and connected to the acid pond of the summit's main crater. Therefore, the steep southern flanks of the volcano could be resting on a low-strength, high-angle discontinuity saturated with circulating and possibly pressurized hydrothermal fluids. This could favor partial edifice collapse and lateral directed explosions as shown recurrently in the volcano's history. The resistivity model also reveals smaller hydrothermal reservoirs in the south-east and northern flanks that are linked to the main historical eruptive fractures and to ancient collapse structures such as the Cratère Amic structure. We discuss the main resistivity structures in relation with the geometry of observed faults, historical eruptive fractures, the dynamics of the near surface hydrothermal system manifestations on the dome and the potential implications for future hazards scenarios .

Numerical Temperature And Fluid-Flow Modelling For The Topographic Effects On Hydrothermal Circulation; A case study in Lucy Strike Vent Field

NASA Astrophysics Data System (ADS)

Erçetin, Engin; Düşünür Doǧan, Doǧa

2017-04-01

The aim of the study is to present a numerical temperature and fluid-flow modelling for the topographic effects on hydrothermal circulation. Bathymetry can create a major disturbance on fluid flow pattern. ANSYS Fluent Computational fluid dynamics software is used for simulations. Coupled fluid flow and temperature quations are solved using a 2-Dimensional control volume finite difference approach. Darcy's law is assumed to hold, the fluid is considered to be anormal Boussinesq incompressible fluid neglecting inertial effects. Several topographic models were simulated and both temperature and fluid flow calculations obtained for this study. The preliminary simulations examine the effect of a ingle bathymetric high on a single plume and the secondary study of simulations investigates the effect of multiple bathymetric highs on multiple plume. The simulations were also performed for the slow spreading Lucky Strike segment along the Mid-Atlantic Ridge (MAR), one of the best studied regions along the MAR, where a 3.4 km deep magma chamber extending 6 km along-axis is found at its center. The Lucky Strike segment displays a transitional morphology between that of the FAMOUS - North FAMOUS segments, which are characterized by well-developed axial valleys typical of slow-spreading segments, and that of the Menez Gwen segment, characterized by an axial high at the segment center. Lucky Strike Segment hosts a central volcano and active vent field located at the segment center and thus constitutes an excellent case study to simulate the effects of bathymetry on fluid flow. Results demonstrate that bathymetric relief has an important influence on hydrothermal flow. Subsurface pressure alterations can be formed by bathymetric highs, for this reason, bathymetric relief ought to be considered while simulating hydrothermal circulation systems. Results of this study suggest the dominant effect of bathymetric highs on fluid flow pattern and Darcy velocities will be presented. Keywords: Hydrothermal Circulation, Lucky Strike, Bathymetry - Topography, Vent Location, Fluid Flow, Numerical Modelling

Singularity analysis: theory and further developments

NASA Astrophysics Data System (ADS)

Cheng, Qiuming

2015-04-01

Since the concept of singularity and local singularity analysis method (LSA) were originally proposed by the author for characterizing the nonlinear property of hydrothermal mineralization processes, the local singularity analysis technique has been successfully applied for identification of geochemical and geophysical anomalies related to various types of mineral deposits. It has also been shown that the singularity is the generic property of singular geo-processes which result in anomalous amounts of energy release or material accumulation within a narrow spatial-temporal interval. In the current paper we introduce several new developments about singularity analysis. First is a new concept of 'fractal density' which describes the singularity of complex phenomena of fractal nature. While the ordinary density possesses a unit of ratio of mass and volume (e.g. g/cm3, kg/m3) or ratio of energy over volume or time (e.g. J/cm3, w/L3, w/s), the fractal density has a unit of ratio of mass over fractal set or energy over fractal set (e.g. g/cmα, kg/mα, J/ mα, w/Lα, where α can be a non-integer). For the matter with fractal density (a non-integer α), the ordinary density of the phenomena (mass or energy) no longer exists and depicts singularity. We demonstrate that most of extreme geo-processes occurred in the earth crust originated from cascade earth dynamics (mental convection, plate tectonics, orogeny and weathering etc) may cause fractal density of mass accumulation or energy release. The examples to be used to demonstrate the concepts of fractal density and singularity are earthquakes, floods, volcanos, hurricanes, heat flow over oceanic ridge, hydrothermal mineralization in orogenic belt, and anomalies in regolith over mine caused by ore and toxic elements vertical migration. Other developments of singularity theory and methodologies including singular Kriging and singularity weights of evidence model for information integration will also be introduced.

Partnering and teamwork to create content for spherical display systems to enhance public literacy in earth system and ocean sciences

NASA Astrophysics Data System (ADS)

Beaulieu, S. E.; Patterson, K.; Joyce, K.; Silva, T.; Madin, K.; Spargo, A.; Brickley, A.; Emery, M.

2013-12-01

Spherical display systems, also known as digital globes, are technologies that, in person or online, can be used to help visualize global datasets and earth system processes. Using the InterRidge Global Database of Active Submarine Hydrothermal Vent Fields and imagery from deep-sea vehicles, we are creating content for spherical display systems to educate and excite the public about dynamic geophysical and biological processes and exploration in the deep ocean. The 'Global Viewport for Virtual Exploration of Deep-Sea Hydrothermal Vents' is a collaboration between the Woods Hole Oceanographic Institution and the Ocean Explorium at New Bedford Seaport, hosting a Magic Planet and Science On a Sphere (SOS), respectively. The main activities in the first year of our project were geared towards team building and content development. Here we will highlight the partnering and teamwork involved in creating and testing the effectiveness of our new content. Our core team is composed of a lead scientist, educators at both institutions, graphic artists, and a professional evaluator. The new content addresses key principles of Earth Science Literacy and Ocean Literacy. We will share the collaborative, iterative process by which we developed two educational pieces, 'Life without sunlight' and 'Smoke and fire underwater' - each focusing on a different set of 3 literacy principles. We will share how we conducted our front-end and formative evaluations and how we focused on 2 NSF Informal Education Impact Categories for our evaluation questionnaire for the public. Each educational piece is being produced as a stand-alone movie and as an interactive, docent-led presentation integrating a number of other datasets available from NOAA's SOS Users Network. The proximity of our two institutions enables a unique evaluation of the learning attained with a stand-alone spherical display vs. live presentations with an SOS.

Hydrothermal Gasification for Waste to Energy

NASA Astrophysics Data System (ADS)

Epps, Brenden; Laser, Mark; Choo, Yeunun

2014-11-01

Hydrothermal gasification is a promising technology for harvesting energy from waste streams. Applications range from straightforward waste-to-energy conversion (e.g. municipal waste processing, industrial waste processing), to water purification (e.g. oil spill cleanup, wastewater treatment), to biofuel energy systems (e.g. using algae as feedstock). Products of the gasification process are electricity, bottled syngas (H2 + CO), sequestered CO2, clean water, and inorganic solids; further chemical reactions can be used to create biofuels such as ethanol and biodiesel. We present a comparison of gasification system architectures, focusing on efficiency and economic performance metrics. Various system architectures are modeled computationally, using a model developed by the coauthors. The physical model tracks the mass of each chemical species, as well as energy conversions and transfers throughout the gasification process. The generic system model includes the feedstock, gasification reactor, heat recovery system, pressure reducing mechanical expanders, and electricity generation system. Sensitivity analysis of system performance to various process parameters is presented. A discussion of the key technological barriers and necessary innovations is also presented.

Effect of hydrothermal liquefaction aqueous phase recycling on bio-crude yields and composition.

PubMed

Biller, Patrick; Madsen, René B; Klemmer, Maika; Becker, Jacob; Iversen, Bo B; Glasius, Marianne

2016-11-01

Hydrothermal liquefaction (HTL) is a promising thermo-chemical processing technology for the production of biofuels but produces large amounts of process water. Therefore recirculation of process water from HTL of dried distillers grains with solubles (DDGS) is investigated. Two sets of recirculation on a continuous reactor system using K2CO3 as catalyst were carried out. Following this, the process water was recirculated in batch experiments for a total of 10 rounds. To assess the effect of alkali catalyst, non-catalytic HTL process water recycling was performed with 9 recycle rounds. Both sets of experiments showed a large increase in bio-crude yields from approximately 35 to 55wt%. The water phase and bio-crude samples from all experiments were analysed via quantitative gas chromatography-mass spectrometry (GC-MS) to investigate their composition and build-up of organic compounds. Overall the results show an increase in HTL conversion efficiency and a lower volume, more concentrated aqueous by-product following recycling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid Synthesis and Formation Mechanism of Core-Shell-Structured La-Doped SrTiO3 with a Nb-Doped Shell

PubMed Central

Park, Nam-Hee; Akamatsu, Takafumi; Itoh, Toshio; Izu, Noriya; Shin, Woosuck

2015-01-01

To provide a convenient and practical synthesis process for metal ion doping on the surface of nanoparticles in an assembled nanostructure, core-shell-structured La-doped SrTiO3 nanocubes with a Nb-doped surface layer were synthesized via a rapid synthesis combining a rapid sol-precipitation and hydrothermal process. The La-doped SrTiO3 nanocubes were formed at room temperature by a rapid dissolution of NaOH pellets during the rapid sol-precipitation process, and the Nb-doped surface (shell) along with Nb-rich edges formed on the core nanocubes via the hydrothermal process. The formation mechanism of the core-shell-structured nanocubes and their shape evolution as a function of the Nb doping level were investigated. The synthesized core-shell-structured nanocubes could be arranged face-to-face on a SiO2/Si substrate by a slow evaporation process, and this nanostructured 10 μm thick thin film showed a smooth surface. PMID:28793420

Hydrogen, Oxygen and Silicon Isotope Systematics of Groundwater-Magma Interaction in Icelandic Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Kleine, B. I.; Stefansson, A.; Halldorsson, S. A.; Martin, W.; Barnes, J.; Jónasson, K.; Franzson, H.

2016-12-01

Magma often encounters groundwater (meteoric or seawater derived) when intruded into the crust. Magma-groundwater interactions result in the formation of hydrothermal fluids which can lead to contact metamorphism and elemental transport in the country rock. In fact, magma-hydrothermal fluid interaction (rather than magma-magmatic fluid interaction) may lead to classic contact metamorphic reactions. In order to explore the importance of hydrothermal fluid during contact metamorphism we use stable isotopes (δD, δ18O, δ30Si) from both active and extinct magma chambers and hydrothermal systems from across Iceland. Quartz grains from various hydrothermal systems, from crustal xenoliths from the Askja central volcano and from the Hafnarfjall pluton, as well as quartz grains associated with low-T zeolites were analysed for δ18O and δ30Si in-situ using SIMS. Whole rock material of these samples was analysed for δD values using a TCEA coupled to an IRMS. Our results indicate that low-T quartz (<150°C) are dominated by negative δ30Si values whereas positive δ30Si values prevail in quartz precipitated at higher T (>300°C). Combining the results from the analyses of δ18O and δD allows further division of samples into (i) seawater and/or rock dominated and (ii) meteoric water dominated hydrothermal systems. In order to isolate the effects of fluid-rock interaction, fluid source and formation temperature at the magma-groundwater contact, δD, δ18O and δ30Si values of rocks and fluids were modeled using the PHREEQC software. Comparison of analytical and model results shows that the isotopic compositions are influenced by multiple processes. In some cases, groundwater penetrates the contact zone and causes alteration at >400°C by groundwater-magma heat interaction. Other cases document "baked" contact zones without groundwater. Our analyses and modeling demonstrates that groundwater flow and permeability are crucial in setting the style of contact metamorphism around high T intrusions.

A Paleoarchean coastal hydrothermal field inhabited by diverse microbial communities: the Strelley Pool Formation, Pilbara Craton, Western Australia.

PubMed

Sugitani, K; Mimura, K; Takeuchi, M; Yamaguchi, T; Suzuki, K; Senda, R; Asahara, Y; Wallis, S; Van Kranendonk, M J

2015-11-01

The 3.4-Ga Strelley Pool Formation (SPF) at the informally named 'Waterfall Locality' in the Goldsworthy greenstone belt of the Pilbara Craton, Western Australia, provides deeper insights into ancient, shallow subaqueous to possibly subaerial ecosystems. Outcrops at this locality contain a thin (<3 m) unit of carbonaceous and non-carbonaceous cherts and silicified sandstones that were deposited in a shallow-water coastal environment, with hydrothermal activities, consistent with the previous studies. Carbonaceous, sulfide-rich massive black cherts with coniform structures up to 3 cm high are characterized by diverse rare earth elements (REE) signatures including enrichment of light [light rare earth elements (LREE)] or middle rare earth elements and by enrichment of heavy metals represented by Zn. The massive black cherts were likely deposited by mixing of hydrothermal and non-hydrothermal fluids. Coniform structures in the cherts are characterized by diffuse laminae composed of sulfide particles, suggesting that unlike stromatolites, they were formed dominantly through physico-chemical processes related to hydrothermal activity. The cherts yield microfossils identical to previously described carbonaceous films, small and large spheres, and lenticular microfossils. In addition, new morphological types such as clusters composed of large carbonaceous spheroids (20-40 μm across each) with fluffy or foam-like envelope are identified. Finely laminated carbonaceous cherts are devoid of heavy metals and characterized by the enrichment of LREE. This chert locally contains conical to domal structures characterized by truncation of laminae and trapping of detrital grains and is interpreted as siliceous stromatolite formed by very early or contemporaneous silicification of biomats with the contribution of silica-rich hydrothermal fluids. Biological affinities of described microfossils and microbes constructing siliceous stromatolites are under investigation. However, this study emphasizes how diverse the microbial community in Paleoarchean coastal hydrothermal environment was. We propose the diversity is at least partially due to the availability of various energy sources in this depositional environment including reducing chemicals and sunlight. © 2015 John Wiley & Sons Ltd.

Magnetic fabrics and fluid flow directions in hydrothermal systems. A case study in the Chaillac Ba-F-Fe deposits (France)

NASA Astrophysics Data System (ADS)

Sizaret, Stanislas; Chen, Yan; Chauvet, Alain; Marcoux, Eric; Touray, Jean Claude

2003-02-01

This study presents a possible use of anisotropy of magnetic susceptibility (AMS) to describe the mineralizing process in hydrothermal systems. Ba-F-Fe-rich deposits within the Chaillac Basin are on the southern border of the Paris Basin. In these deposits hydrothermal textures and tectonic structures have been described in veins, sinters, and sandstone cemented by hydrothermal goethite. 278 oriented cores from 24 sites have been collected in these formations. In addition, a lateritic duricrust superimposed on the hydrothermal formation has been sampled. Rock magnetic investigations show that the principal magnetic carrier is goethite for the hydrothermal mineralization and for the laterite level. The AMS measurements show distinguishable behaviors in the different mineralogical and geological contexts. The K1 magnetic lineation (maximum axis) is strongly inclined for the vertical veins. For the horizontally mineralized sinters, the magnetic lineation is almost horizontal with an azimuth similar to the sedimentary flow direction. The AMS of goethite-rich sandstone close to the veins shows strongly inclined K1 as they are probably influenced by the vertical veins; however, when the distance from the vein is larger than 1 m, the AMS presents rather horizontal K1 directions, parallel to the sedimentary flow. The laterite has a foliation dominance of AMS with vertically well-grouped K3 axes and scattered K1 and K2 axes. Field structural observations suggest that the ore deposit is mainly controlled by EW extension tectonics associated with NS trending normal faults. Combining the AMS results on the deposit with vein textures and field data a model is proposed in which AMS results are interpreted in terms of hydrothermal fluid flow. This work opens a new investigation field to constrain hydrodynamic models using the AMS method. Textural study combined with efficient AMS fabric measurements should be used for systematic investigation to trace flow direction in fissures and in sand porosity.

Dissolved iron anomaly in the deep tropical-subtropical Pacific: Evidence for long-range transport of hydrothermal iron

NASA Astrophysics Data System (ADS)

Wu, Jingfeng; Wells, Mark L.; Rember, Robert

2011-01-01

Dissolved iron profiles along a north-south transect along 158°W in the tropical Pacific show evidence of two deepwater anomalies. The first extends from Station ALOHA (22.78°N) to the equator at ˜1000-1500 m and lies below the maximum apparent oxygen utilization and nutrient (N, P) concentrations. The feature is not supported by vertical export processes, but instead corresponds with the lateral dilution field of δ 3He derived from the Loihi seamount, Hawaii, though a sediment source associated with the Hawaiian Island Chain cannot be entirely ruled out. The second, deeper (2000-3000 m) anomaly occurs in tropical South Pacific waters (7°S) and also does not correlate with the depths of maximum nutrient concentrations or apparent oxygen utilization, but it does coincide closely with δ 3He emanating from the East Pacific Rise, more than 5000 km to the east. We hypothesize that these anomalies represent the long-range (>2000 km) transport of hydrothermal iron residuals, stabilized against scavenging by complexation with excess organic ligands in the plume source regions. Such trace leakage of hydrothermal iron to distal plume regions would have been difficult to identify in most hydrothermal vent mapping studies because low analytical detection limits were not needed for the proximal plume regions. These findings suggest that hydrothermal activity may represent a major source of dissolved iron throughout the South Pacific deep basin today, as well as other regions having high mid-ocean spreading rates in the geologic past. In particular, we hypothesize that high spreading rates along the South Atlantic and Southern Ocean mid-oceanic ridges, combined with the upwelling ventilation of these distal hydrothermal plumes, may have increased ocean productivity and carbon export in the Southern Ocean. Assessing the magnitude and persistence of dissolved hydrothermal iron in basin scale deep waters will be important for understanding the marine biogeochemistry of iron and, potentially, on ocean productivity and climate change during the geologic past.

Preparation, photoluminescent properties and luminescent dynamics of BaAlF{sub 5}:Eu{sup 2+} nanophosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Wei; College of Life Science, Dalian Nationalities University, Dalian, Liaoning 116600; Hua, Ruinian, E-mail: rnhua@dlnu.edu.cn

2014-12-15

Graphical abstract: Rice-shaped BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via one-pot hydrothermal process. The as-prepared BaAlF{sub 5}:Eu{sup 2+} are composed of many particles with an average diameter of 40 nm. When excited at 260 nm, the sharp line emission located at 361 nm of Eu{sup 2+} was observed. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The strong ultraviolet emission of Eu{sup 2+} ions in BaAlF{sub 5}:Eu{sup 2+} nanoparticles suggests that these nanoparticles may have potential applications for sensing, solid-state lasers and spectrometer calibration. - Highlights: • BaAlF{sub 5}:Eu{sup 2+} nanophosphors were synthesized via amore » mild hydrothermal process. • The Van and Huang models were used to research the mechanism of concentration quenching. • The optimum doping concentration of Eu2+ was confirmed to be 5 mol%. - Abstract: Eu{sup 2+}-doped BaAlF{sub 5} nanophosphors were synthesized via a facile one-pot hydrothermal method. The final products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. XRD results showed that the prepared samples are single-phase. The FE-SEM and TEM images indicated that the prepared BaAlF{sub 5}:Eu{sup 2+} nanophosphors are composed of many rice-shaped particles with an average diameter of 40 nm. When excited at 260 nm, BaAlF{sub 5}:Eu{sup 2+} nanophosphors exhibit the sharp line emissions of Eu{sup 2+} at room temperature. The optimum doping concentration of Eu{sup 2+} was confirmed to be 5 mol%. The Van and Huang models were used to study the mechanism of concentration quenching and the electric dipole–dipole interaction between Eu{sup 2+} can be deduced to be a dominant for quenching fluorescence in BaAlF{sub 5}:Eu{sup 2+} nanophosphors. The strong ultraviolet emission of Eu{sup 2+} in BaAlF{sub 5}:Eu{sup 2+} nanophosphors suggests that these nanoparticles may have potential applications for sensing, spectrometer calibration and solid-state lasers.« less

Synthesis of multi-hierarchical structured yttria-stabilized zirconia powders and their enhanced thermophysical properties

NASA Astrophysics Data System (ADS)

Cao, Fengmei; Gao, Yanfeng; Chen, Hongfei; Liu, Xinling; Tang, Xiaoping; Luo, Hongjie

2013-06-01

Multi-hierarchical structured yttria-stabilized zirconia (YSZ) powders were successfully synthesized by a hydrothermal-calcination process. The morphology, crystallinity, and microstructure of the products were characterized by SEM, XRD, TEM, and BET. A possible formation mechanism of the unique structure formed during hydrothermal processing was also investigated. The measured thermophysical results indicated that the prepared YSZ powders had a low thermal conductivity (0.63-1.27 W m-1 K-1), good short-term high-temperature stability up to 1300 °C. The influence of the morphology and microstructure on their thermophysical properties was briefly discussed. The unique multi-hierarchical structure makes the prepared YSZ powders candidates for use in enhanced applications involving thermal barrier coatings.

Hydrothermal activity lowers trophic diversity in Antarctic hydrothermal sediments

NASA Astrophysics Data System (ADS)

Bell, James B.; Reid, William D. K.; Pearce, David A.; Glover, Adrian G.; Sweeting, Christopher J.; Newton, Jason; Woulds, Clare

2017-12-01

Hydrothermal sediments are those in which hydrothermal fluid is discharged through sediments and are one of the least studied deep-sea ecosystems. We present a combination of microbial and biochemical data to assess trophodynamics between and within hydrothermal and background areas of the Bransfield Strait (1050-1647 m of depth). Microbial composition, biomass, and fatty acid signatures varied widely between and within hydrothermally active and background sites, providing evidence of diverse metabolic activity. Several species had different feeding strategies and trophic positions between hydrothermally active and inactive areas, and the stable isotope values of consumers were not consistent with feeding morphology. Niche area and the diversity of microbial fatty acids was lowest at the most hydrothermally active site, reflecting trends in species diversity. Faunal uptake of chemosynthetically produced organics was relatively limited but was detected at both hydrothermal and non-hydrothermal sites, potentially suggesting that hydrothermal activity can affect trophodynamics over a much wider area than previously thought.

One-step hydrothermal synthesis of hexangular starfruit-like vanadium oxide for high power aqueous supercapacitors

NASA Astrophysics Data System (ADS)

Shao, Jie; Li, Xinyong; Qu, Qunting; Zheng, Honghe

2012-12-01

Homogenous hexangular starfruit-like vanadium oxide was prepared for the first time by a one-step hydrothermal method. The assembly process of hexangular starfruit-like structure was observed from TEM images. The electrochemical performance of starfruit-like vanadium oxide was examined by cyclic voltammetry and galvanostatic charge/discharge. The obtained starfruit-like vanadium oxide exhibits a high power capability (19 Wh kg-1 at the specific power of 3.4 kW kg-1) and good cycling stability for supercapacitors application.

Toxicity evaluation of process water from hydrothermal carbonization of sugarcane industry by-products.

PubMed

Fregolente, Laís Gomes; Miguel, Thaiz Batista Azevedo Rangel; de Castro Miguel, Emilio; de Almeida Melo, Camila; Moreira, Altair Benedito; Ferreira, Odair Pastor; Bisinoti, Márcia Cristina

2018-03-29

Hydrothermal carbonization (HTC) is a thermochemical process carried out in an aqueous medium. It is capable of converting biomass into a solid, carbon-rich material (hydrochar), and producing a liquid phase (process water) which contains the unreactive feedstock and/or chemical intermediates from the carbonization reaction. The aim of this study was to evaluate the characteristics of process water generated by HTC from vinasse and sugarcane bagasse produced by sugarcane industry and to evaluate its toxicity to both marine (using Artemia salina as a model organism) and the terrestrial environment (through seed germination studies of maize, lettuce, and tomato). The experiments showed that concentrated process water completely inhibited germination of maize, lettuce, and tomato seeds. On the other hand, diluted process water was able to stimulate seedlings of maize and tomato and enhance root and shoot growth. For Artemia, the LC 50 indicated that the process water is practically non-toxic; however, morphological changes, especially damages to the digestive tube and antennas of Artemia, were observed for the concentration of 1000 mg C L -1 .

Extensive Genome Rearrangements and Multiple Horizontal Gene Transfers in a Population of Pyrococcus Isolates from Vulcano Island, Italy▿ †

PubMed Central

White, James R.; Escobar-Paramo, Patricia; Mongodin, Emmanuel F.; Nelson, Karen E.; DiRuggiero, Jocelyne

2008-01-01

The extent of chromosome rearrangements in Pyrococcus isolates from marine hydrothermal vents in Vulcano Island, Italy, was evaluated by high-throughput genomic methods. The results illustrate the dynamic nature of the genomes of the genus Pyrococcus and raise the possibility of a connection between rapidly changing environmental conditions and adaptive genomic properties. PMID:18723649

Mass transfer processes in a post eruption hydrothermal system: Parameterisation of microgravity changes at Te Maari craters, New Zealand

NASA Astrophysics Data System (ADS)

Miller, Craig A.; Currenti, Gilda; Hamling, Ian; Williams-Jones, Glyn

2018-05-01

Fluid transfer and ground deformation at hydrothermal systems occur both as a precursor to, or as a result of, an eruption. Typically studies focus on pre-eruption changes to understand the likelihood of unrest leading to eruption; however, monitoring post-eruption changes is important for tracking the return of the system towards background activity. Here we describe processes occurring in a hydrothermal system following the 2012 eruption of Upper Te Maari crater on Mt Tongariro, New Zealand, from observations of microgravity change and deformation. Our aim is to assess the post-eruption recovery of the system, to provide a baseline for long-term monitoring. Residual microgravity anomalies of up to 92 ± 11 μGal per year are accompanied by up to 0.037 ± 0.01 m subsidence. We model microgravity changes using analytic solutions to determine the most likely geometry and source location. A multiobjective inversion tests whether the gravity change models are consistent with the observed deformation. We conclude that the source of subsidence is separate from the location of mass addition. From this unusual combination of observations, we develop a conceptual model of fluid transfer within a condensate layer, occurring in response to eruption-driven pressure changes. We find that depressurisation drives the evacuation of pore fluid, either exiting the system completely as vapour through newly created vents and fumaroles, or migrating to shallower levels where it accumulates in empty pore space, resulting in positive gravity changes. Evacuated pores then collapse, causing subsidence. In addition we find that significant mass addition occurs from influx of meteoric fluids through the fractured hydrothermal seal. Long-term combined microgravity and deformation monitoring will allow us to track the resealing and re-pressurisation of the hydrothermal system and assess what hazard it presents to thousands of hikers who annually traverse the volcano, within 2 km of the eruption site.

Martian Magmatic-Driven Hydrothermal Sites: Potential Sources of Energy, Water, and Life

NASA Technical Reports Server (NTRS)

Anderson, R. C.; Dohm, J. M.; Baker, V. R.; Ferris, J. C.; Hare, T. M.; Tanaka, K. L.; Klemaszewski, J. E.; Skinner, J. A.; Scott, D. H.

2000-01-01

Magmatic-driven processes and impact events dominate the geologic record of Mars. Such recorded geologic activity coupled with significant evidence of past and present-day water/ice, above and below the martian surface, indicate that hydrothermal environments certainly existed in the past and may exist today. The identification of such environments, especially long-lived magmatic-driven hydrothermal environments, provides NASA with significant target sites for future sample return missions, since they (1) could favor the development and sustenance of life, (2) may comprise a large variety of exotic mineral assemblages, and (3) could potentially contain water/ice reservoirs for future Mars-related human activities. If life developed on Mars, the fossil record would presumably be at its greatest concentration and diversity in environments where long-term energy sources and water coexisted such as at sites where long-lived, magmatic-driven hydrothermal activity occurred. These assertions are supported by terrestrial analogs. Small, single-celled creatures (prokaryotes) are vitally important in the evolution of the Earth; these prokaryotes are environmentally tough and tolerant of environmental extremes of pH, temperature, salinity, and anoxic conditions found around hydrothermal vents. In addition, there is a great ability for bacteria to survive long periods of geologic time in extreme conditions, including high temperature hydrogen sulfide and sulfur erupted from Mount St. Helens volcano. Our team of investigators is conducting a geological investigation using multiple mission-derived datasets (e.g., existing geologic map data, MOC imagery, MOLA, TES image data, geophysical data, etc.) to identify prime target sites of hydrothermal activity for future hydrological, mineralogical, and biological investigations. The identification of these sites will enhance the probability of success for future missions to Mars.

Satellite observations of fumarole activity at Aluto volcano, Ethiopia: Implications for geothermal monitoring and volcanic hazard

NASA Astrophysics Data System (ADS)

Braddock, Mathilde; Biggs, Juliet; Watson, Iain M.; Hutchison, William; Pyle, David M.; Mather, Tamsin A.

2017-07-01

Fumaroles are the surface manifestation of hydrothermal circulation and can be influenced by magmatic, hydrothermal, hydrological and tectonic processes. This study investigates the temporal changes in fumarole temperatures and spatial extent on Aluto, a restless volcano in the Main Ethiopian Rift (MER), in order to better understand the controls on fluid circulation and the interaction between the magmatic and hydrothermal systems. Thermal infrared (TIR) satellite images, acquired by the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) over the period of 2004 to 2016, are used to generate time series of the fumarole temperatures and areas. The thermal anomalies identified in the ASTER images coincide with known fumaroles with temperatures > 80 °C and are located on or close to fault structures, which provide a pathway for the rising fluids. Most of the fumaroles, including those along the major zone of hydrothermal upwelling, the Artu Jawe Fault Zone, have pixel-integrated temperature variations of only 2 ± 1.5 °C. The exception are the Bobesa fumaroles located on a hypothesised caldera ring fault which show pixel-integrated temperature changes of up to 9 °C consistent with a delayed response of the hydrothermal system to precipitation. We conclude that fumaroles along major faults are strongly coupled to the magmatic-hydrothermal system and are relatively stable with time, whereas those along shallower structures close to the rift flank are more strongly influenced by seasonal variations in groundwater flow. The use of remote sensing data to monitor the thermal activity of Aluto provides an important contribution towards understanding the behaviour of this actively deforming volcano. This method could be used at other volcanoes around the world for monitoring and geothermal exploration.

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.

Lithium manganese oxide (LiMn{sub 2}O{sub 4}) nanoparticles synthesized by hydrothermal method as adsorbent of lithium recovery process from geothermal fluid of Lumpur Sidoarjo

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noerochim, Lukman, E-mail: lukman@mat-eng.its.ac.id; Sapputra, Gede Panca Ady; Widodo, Amien

2016-04-19

Lumpur Sidoarjo is one of geothermal fluid types which has a great potential as source of lithium. Adsorption method with Lithium Manganese Oxide (LiMn{sub 2}O{sub 4}) as an adsorbent has been chosen for lithium recovery process due to low production cost and environmental friendly. LiMn{sub 2}O{sub 4} was synthesized by hydrothermal method at 200 °C for 24 hrs, 48 hrs, and 72 hrs. As prepared LiMn{sub 2}O{sub 4} 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 LiMn{sub 2}O{sub 4}more » (JCPDS card no 35-0782) with no impurity peaks detected. SEM images show that LiMn{sub 2}O{sub 4} 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%.« less

Cell-wall structural changes in wheat straw pretreated for bioethanol production

PubMed Central

Kristensen, Jan B; Thygesen, Lisbeth G; Felby, Claus; Jørgensen, Henning; Elder, Thomas

2008-01-01

Background Pretreatment is an essential step in the enzymatic hydrolysis of biomass and subsequent production of bioethanol. Recent results indicate that only a mild pretreatment is necessary in an industrial, economically feasible system. The Integrated Biomass Utilisation System hydrothermal pretreatment process has previously been shown to be effective in preparing wheat straw for these processes without the application of additional chemicals. In the current work, the effect of the pretreatment on the straw cell-wall matrix and its components are characterised microscopically (atomic force microscopy and scanning electron microscopy) and spectroscopically (attenuated total reflectance Fourier transform infrared spectroscopy) in order to understand this increase in digestibility. Results The hydrothermal pretreatment does not degrade the fibrillar structure of cellulose but causes profound lignin re-localisation. Results from the current work indicate that wax has been removed and hemicellulose has been partially removed. Similar changes were found in wheat straw pretreated by steam explosion. Conclusion Results indicate that hydrothermal pretreatment increases the digestibility by increasing the accessibility of the cellulose through a re-localisation of lignin and a partial removal of hemicellulose, rather than by disruption of the cell wall. PMID:18471316

Synthesis of metal-doped Mn-Zn ferrite from the leaching solutions of vanadium slag using hydrothermal method

NASA Astrophysics Data System (ADS)

Liu, Shiyuan; Wang, Lijun; Chou, Kuochih

2018-03-01

Using vanadium slag as raw material, Metal-doped Mn-Zn ferrites were synthesized by multi-step processes including chlorination of iron and manganese by NH4Cl, selective oxidation of Fe cation, and hydrothermal synthesis. The phase composition and magnetic properties of synthesized metal-doped Mn-Zn ferrite were characterized by X-ray powder diffraction, Raman spectroscopy, transmission electron microscopy (TEM), X-ray photon spectra (XPS) and physical property measurement. It was found that Mn/Zn mole ratio significantly affected the magnetic properties and ZnCl2 content significantly influenced the purity of the phase of ferrite. Synthesized metal-doped Mn-Zn ferrite, exhibiting a larger saturation magnetization (Ms = 60.01 emu/g) and lower coercivity (Hc = 8.9 Oe), was obtained when the hydrothermal temperature was controlled at 200 °C for 12 h with a Mn/Zn mole ratio of 4. The effect of ZnCl2 content, Mn/Zn mole ratio and temperature on magnetic properties of the synthesized metal-doped Mn-Zn ferrite were systemically investigated. This process provided a new insight to utilize resources in the aim of obtaining functional materials.

Natural fracking and the genesis of five-element veins

NASA Astrophysics Data System (ADS)

Markl, Gregor; Burisch, Mathias; Neumann, Udo

2016-08-01

Hydrothermal Ag-Co-Ni-Bi-As (five-element vein type) ore deposits show very conspicuous textures of the native elements silver, bismuth, and arsenic indicating formation from a rapid, far-from-equilibrium process. Such textures include up to dm-large tree- and wire-like aggregates overgrown by Co-Ni-Fe arsenides and mostly carbonates. Despite the historical and contemporary importance of five-element vein type deposits as sources of silver, bismuth, and cobalt, and despite of spectacular museum specimens, their process of formation is not yet understood and has been a matter of debate since centuries. We propose, based on observations from a number of classical European five-element vein deposits and carbon isotope analyses, that "natural fracking," i.e., liberation of hydrocarbons or hydrocarbon-bearing fluids during break up of rocks in the vicinity of an active hydrothermal system and mixing between these hydrocarbons (e.g., methane and/or methane-bearing fluids) and a metal-rich hydrothermal fluid is responsible for ore precipitation and the formation of the unusual ore textures and assemblages. Thermodynamic and isotope mixing calculations show that the textural, chemical, and isotopic features of the investigated deposits can entirely be explained by this mechanism.

Evaluation of LANDSAT MSS vs TM simulated data for distinguishing hydrothermal alteration

NASA Technical Reports Server (NTRS)

Abrams, M. J.; Kahle, A. B.; Madura, D. P.; Soha, J. M.

1978-01-01

The LANDSAT Follow-On (LFO) data was simulated to demonstrate the mineral exploration capability of this system for segregating different types of hydrothermal alteration and to compare this capability with that of the existing LANDSAT system. Multispectral data were acquired for several test sites with the Bendix 24-channel MSDS scanner. Contrast enhancements, band ratioing, and principal component transformations were used to process the simulated LFO data for analysis. For Red Mountain, Arizona, the LFO data allowed identification of silicified areas, not identifiable with LANDSAT 1 and 2 data. The improved LFO resolution allowed detection of small silicic outcrops and of a narrow silicified dike. For Cuprite - Ralston, Nevada, the LFO spectral bands allowed discrimination of argillic and opalized altered areas; these could not be spectrally discriminated using LANDSAT 1 and 2 data. Addition of data from the 1.3- and 2.2- micrometer regions allowed better discriminations of hydrothermal alteration types.

Fundamental Study on One-Dimensional-Array Medical Ultrasound Probe with Piezoelectric Polycrystalline Film by Hydrothermal Method: Experimental Fabrication of One-Dimensional-Array Ultrasound Probe

NASA Astrophysics Data System (ADS)

Endo, Akito; Kawashima, Norimichi; Takeuchi, Shinichi; Ishikawa, Mutsuo; Kurosawa, Minoru Kuribayashi

2007-07-01

We deposited a lead zirconate titanete (PZT) polycrystalline film on a titanium substrate by the hydrothermal method and fabricated a transducer using the PZT film for use as an ultrasound probe. A 10 MHz miniature one-dimensional-array medical ultrasound probe containing the PZT film was developed. After sputtering titanium on the surface of a hydroxyapatite substrate, the titanium film on the substrate was etched by the photolithography to form a one-dimensional titanium film electrode array. We could thus fabricate a miniature one-dimensional-array ultrasound probe by the hydrothermal method. Transmitted ultrasound pulses from a 10 MHz commercial ultrasound probe were received by the newly fabricated one-dimensional-array ultrasound probe. The fabrication process of the probe and the results of experiments on receiving waveforms were reported in this paper.

Geothermal energy resources of wadi Al-Lith, Saudi Arabia

NASA Astrophysics Data System (ADS)

Lashin, A.; Chandrasekharam, D.; Al Arifi, N.; Al Bassam, A.; Varun, C.

2014-09-01

The entire western Arabian shield is the domain of both hydrothermal and enhanced geothermal systems associated with volcanic centres (Harrats) and high heat generating granites. The most prominent sites of hydrothermal systems are located around Al-Lith and Jizan. The hydrothermal system in Al Lith is controlled by high heat generating (∼11 μW/m3) post orogenic granites. The high heat flow value of >80 mW/m2 across Al-Lith coast is due to such granite intrusives, presence of dike swarms that intrude into the granites as well as position of Moho at shallow level. Although the thermal waters are chloride rich, Red Sea involvement is not observed. Long residence time and water rock interaction with granites are the main processes responsible for chloride enrichment in the thermal waters. Oxygen isotope shift indicates presence of high temperature geothermal system in the area. The tritium values indicate that the circulating waters are >75 years old.

Hydrothermal synthesis of nanocubes of sillenite type compounds for photovoltaic applications and solar energy conversion of carbon dioxide to fuels

DOEpatents

Subramanian, Vaidyanathan; Murugesan, Sankaran

2014-04-29

The present invention relates to formation of nanocubes of sillenite type compounds, such as bismuth titanate, i.e., Bi.sub.12TiO.sub.20, nanocubes, via a hydrothermal synthesis process, with the resulting compound(s) having multifunctional properties such as being useful in solar energy conversion, environmental remediation, and/or energy storage, for example. In one embodiment, a hydrothermal method is disclosed that transforms nanoparticles of TiO.sub.2 to bismuth titanate, i.e., Bi.sub.12TiO.sub.20, nanocubes, optionally loaded with palladium nanoparticles. The method includes reacting titanium dioxide nanotubes with a bismuth salt in an acidic bath at a temperature sufficient and for a time sufficient to form bismuth titanate crystals, which are subsequently annealed to form bismuth titanate nanocubes. After annealing, the bismuth titanate nanocubes may be optionally loaded with nano-sized metal particles, e.g., nanosized palladium particles.

Nanodiamond finding in the hyblean shallow mantle xenoliths.

PubMed

Simakov, S K; Kouchi, A; Mel'nik, N N; Scribano, V; Kimura, Y; Hama, T; Suzuki, N; Saito, H; Yoshizawa, T

2015-06-01

Most of Earth's diamonds are connected with deep-seated mantle rocks; however, in recent years, μm-sized diamonds have been found in shallower metamorphic rocks, and the process of shallow-seated diamond formation has become a hotly debated topic. Nanodiamonds occur mainly in chondrite meteorites associated with organic matter and water. They can be synthesized in the stability field of graphite from organic compounds under hydrothermal conditions. Similar physicochemical conditions occur in serpentinite-hosted hydrothermal systems. Herein, we report the first finding of nanodiamonds, primarily of 6 and 10 nm, in Hyblean asphaltene-bearing serpentinite xenoliths (Sicily, Italy). The discovery was made by electron microscopy observations coupled with Raman spectroscopy analyses. The finding reveals new aspects of carbon speciation and diamond formation in shallow crustal settings. Nanodiamonds can grow during the hydrothermal alteration of ultramafic rocks, as well as during the lithogenesis of sediments bearing organic matter.

Wheat bran biorefinery--a detailed investigation on hydrothermal and enzymatic treatment.

PubMed

Reisinger, Michael; Tirpanalan, Ozge; Prückler, Michael; Huber, Florian; Kneifel, Wolfgang; Novalin, Senad

2013-09-01

Due to the enormous quantities arising in the milling industry and its specific properties, wheat bran can be considered as a feedstock for future biorefineries. In the present work, a detailed investigation was carried out on the hydrothermal (140-200°C) and enzymatic treatment of wheat bran. After hydrothermal pretreatment and a subsequent enzymatic hydrolysis a glucose yield of 65% and 90% was achieved, respectively. Interestingly, the hemicelluloses could be disintegrated to monomers only to approx. 50%. About 70% of the proteins were dissolved, however, practically no free amino acids were obtained under given conditions. Severe treatment conditions induce elevated losses of some amino acids. Minerals could be extracted almost completely. To disintegrate fat into glycerol and fatty acids severe process conditions were necessary. The formation of undesired by-products such as furfural or hydroxymethylfurfural starts at approx. 180°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrothermal Alteration at Lonar Crater, India and Elemental Variations in Impact Crater Clays

NASA Technical Reports Server (NTRS)

Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Misra, S.; Narasimham, V.

2005-01-01

The role of hydrothermal alteration and chemical transport involving impact craters could have occurred on Mars, the poles of Mercury and the Moon, and other small bodies. We are studying terrestrial craters of various sizes in different environments to better understand aqueous alteration and chemical transport processes. The Lonar crater in India (1.8 km diameter) is particularly interesting being the only impact crater in basalt. In January of 2004, during fieldwork in the ejecta blanket around the rim of the Lonar crater we discovered alteration zones not previously described at this crater. The alteration of the ejecta blanket could represent evidence of localized hydrothermal activity. Such activity is consistent with the presence of large amounts of impact melt in the ejecta blanket. Map of one area on the north rim of the crater containing highly altered zones at least 3 m deep is shown.

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.

Fault Zone Permeability Decrease Following Large Earthquakes in a Hydrothermal System

NASA Astrophysics Data System (ADS)

Shi, Zheming; Zhang, Shouchuan; Yan, Rui; Wang, Guangcai

2018-02-01

Seismic wave shaking-induced permeability enhancement in the shallow crust has been widely observed. Permeability decrease, however, is seldom reported. In this study, we document coseismic discharge and temperature decrease in a hot spring following the 1996 Lijiang Mw 7.0 and the 2004 Mw 9.0 earthquakes in the Balazhang geothermal field. We use three different models to constrain the permeability change and the mechanism of coseismic discharge decrease, and we use an end-member mixing model for the coseismic temperature change. Our results show that the earthquake-induced permeability decrease in the fault zone reduced the recharge from deep hot water, which may be the mechanism that explains the coseismic discharge and temperature responses. The changes in the hot spring response reflect the dynamic changes in the hydrothermal system; in the future, the earthquake-induced permeability decrease should be considered when discussing controls on permeability.

Rapid hydrothermal cooling above the axial melt lens at fast-spreading mid-ocean ridge

NASA Astrophysics Data System (ADS)

Zhang, Chao; Koepke, Juergen; Kirchner, Clemens; Götze, Niko; Behrens, Harald

2014-09-01

Axial melt lenses sandwiched between the lower oceanic crust and the sheeted dike sequences at fast-spreading mid-ocean ridges are assumed to be the major magma source of oceanic crust accretion. According to the widely discussed ``gabbro glacier'' model, the formation of the lower oceanic crust requires efficient cooling of the axial melt lens, leading to partial crystallization and crystal-melt mush subsiding down to lower crust. These processes are believed to be controlled by periodical magma replenishment and hydrothermal circulation above the melt lens. Here we quantify the cooling rate above melt lens using chemical zoning of plagioclase from hornfelsic recrystallized sheeted dikes drilled from the East Pacific at the Integrated Ocean Drilling Program Hole 1256D. We estimate the cooling rate using a forward modelling approach based on CaAl-NaSi interdiffusion in plagioclase. The results show that cooling from the peak thermal overprint at 1000-1050°C to 600°C are yielded within about 10-30 years as a result of hydrothermal circulation above melt lens during magma starvation. The estimated rapid hydrothermal cooling explains how the effective heat extraction from melt lens is achieved at fast-spreading mid-ocean ridges.

The inevitable journey to being

PubMed Central

Russell, Michael J.; Nitschke, Wolfgang; Branscomb, Elbert

2013-01-01

Life is evolutionarily the most complex of the emergent symmetry-breaking, macroscopically organized dynamic structures in the Universe. Members of this cascading series of disequilibria-converting systems, or engines in Cottrell's terminology, become ever more complicated—more chemical and less physical—as each engine extracts, exploits and generates ever lower grades of energy and resources in the service of entropy generation. Each one of these engines emerges spontaneously from order created by a particular mother engine or engines, as the disequilibrated potential daughter is driven beyond a critical point. Exothermic serpentinization of ocean crust is life's mother engine. It drives alkaline hydrothermal convection and thereby the spontaneous production of precipitated submarine hydrothermal mounds. Here, the two chemical disequilibria directly causative in the emergence of life spontaneously arose across the mineral precipitate membranes separating the acidulous, nitrate-bearing CO2-rich, Hadean sea from the alkaline and CH4/H2-rich serpentinization-generated effluents. Essential redox gradients—involving hydrothermal CH4 and H2 as electron donors, CO2 and nitrate, nitrite, and ferric iron from the ambient ocean as acceptors—were imposed which functioned as the original ‘carbon-fixing engine’. At the same time, a post-critical-point (milli)voltage pH potential (proton concentration gradient) drove the condensation of orthophosphate to produce a high energy currency: ‘the pyrophosphatase engine’. PMID:23754808

Emplacement dynamics and hydrothermal alteration of the Atengo ignimbrite, southern Sierra Madre Occidental, northwestern Mexico

NASA Astrophysics Data System (ADS)

Agarwal, Amar; Alva-Valdivia, L. M.; Rivas-Sánchez, M. L.; Herrero-Bervera, E.; Urrutia-Fucugauchi, J.; Espejel-García, V.

2017-12-01

The Sierra Madre Occidental is a thick continental arc related to the subduction of the Farallon plate beneath North America resulting in a very intense and widespread Cretaceous to Cenozoic magmatic and tectonic activity. The 28 My old Atengo ignimbrite outcrops in the southern Sierra Madre Occidental, northwestern Mexico. From 12 sites that belong to various pyroclastic and lava flows emplaced during two pulses in the Oligocene (ca. 32-28 Ma) and Early Miocene (ca. 24-20 Ma), 97 rock specimens were drilled. The mineralogical and rock magnetic properties of the Atengo ignimbrite are compared with the surrounding volcanic rocks to identify the eruption mechanism, and with the El Castillo Ignimbrite, Veracruz, Mexico, to understand the depositional conditions. The comparisons reveal that the Atengo ignimbrite erupted from a single source, but less violently than the El Castillo ignimbrite, and cooled rapidly, inhibiting the formation of subhedral grains. The source of the Atengo Ignimbrite was a Plinian-type eruption, and the characteristic mineralogical and textural properties of each flow are related to different stages of the Plinian-type eruption. Further more, hydrothermal fluids were active during the last stages of volcanism, and caused moderate to intense alteration, especially in the ignimbrites, where high permeability aided the movement of hydrothermal fluids.

The inevitable journey to being.

PubMed

Russell, Michael J; Nitschke, Wolfgang; Branscomb, Elbert

2013-07-19

Life is evolutionarily the most complex of the emergent symmetry-breaking, macroscopically organized dynamic structures in the Universe. Members of this cascading series of disequilibria-converting systems, or engines in Cottrell's terminology, become ever more complicated-more chemical and less physical-as each engine extracts, exploits and generates ever lower grades of energy and resources in the service of entropy generation. Each one of these engines emerges spontaneously from order created by a particular mother engine or engines, as the disequilibrated potential daughter is driven beyond a critical point. Exothermic serpentinization of ocean crust is life's mother engine. It drives alkaline hydrothermal convection and thereby the spontaneous production of precipitated submarine hydrothermal mounds. Here, the two chemical disequilibria directly causative in the emergence of life spontaneously arose across the mineral precipitate membranes separating the acidulous, nitrate-bearing CO2-rich, Hadean sea from the alkaline and CH4/H2-rich serpentinization-generated effluents. Essential redox gradients-involving hydrothermal CH4 and H2 as electron donors, CO2 and nitrate, nitrite, and ferric iron from the ambient ocean as acceptors-were imposed which functioned as the original 'carbon-fixing engine'. At the same time, a post-critical-point (milli)voltage pH potential (proton concentration gradient) drove the condensation of orthophosphate to produce a high energy currency: 'the pyrophosphatase engine'.

An integrtated approach to the use of Landsat TM data for gold exploration in west central Nevada

NASA Technical Reports Server (NTRS)

Mouat, D. A.; Myers, J. S.; Miller, N. L.

1987-01-01

This paper represents an integration of several Landsat TM image processing techniques with other data to discriminate the lithologies and associated areas of hydrothermal alteration in the vicinity of the Paradise Peak gold mine in west central Nevada. A microprocessor-based image processing system and an IDIMS system were used to analyze data from a 512 X 512 window of a Landsat-5 TM scene collected on June 30, 1984. Image processing techniques included simple band composites, band ratio composites, principal components composites, and baseline-based composites. These techniques were chosen based on their ability to discriminate the spectral characteristics of the products of hydrothermal alteration as well as of the associated regional lithologies. The simple band composite, ratio composite, two principal components composites, and the baseline-based composites separately can define the principal areas of alteration. Combined, they provide a very powerful exploration tool.

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.

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 R.

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 l) approximately l 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 l 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.

Novel three-dimensional dandelion-like TiO{sub 2} structure with high photocatalytic activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bai Xuelian; Xie Bin; Pan Nan

2008-03-15

Pure rutile phase crystalline TiO{sub 2} powder with novel 3D dandelion-like structure was synthesized by using a facile hydrothermal method with TiCl{sub 3} as the main starting material. In such a 3D structure, the nanometer-scale construction elements aggregate together and form a micrometer-scale artificial unit. The typical 3D dandelion structure has an average diameter of 1.5-2 {mu}m and is packed radially by nanorods with [001] preference growth direction. Each individual nanorod is hundreds of nanometers in length, and tens of nanometers in diameter. The obtained 3D dandelion-like TiO{sub 2} powder has a high photocatalytic activity, which is equivalent to thatmore » of the commercial available P25 titania powder. Mechanisms of the formation of the dandelion-like structure were also discussed. A different oxidation process of Ti(III) to Ti(IV) during hydrothermal was suggested. - Graphical abstract: Rutile-phase TiO{sub 2} powders with novel 3D dandelion-like structures were synthesized. This kind of 3D artificial hierarchical titania structure has the advantage of reserving the novel nanometer-scale properties while providing us the easiness of storing and handling as we routinely enjoyed for the micrometer-scale materials. A different oxidation process of Ti(III) to Ti(IV) during hydrothermal process was suggested.« less

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.

Assessing the environmental impact of energy production from hydrochar generated via hydrothermal carbonization of food wastes.

PubMed

Berge, Nicole D; Li, Liang; Flora, Joseph R V; Ro, Kyoung S

2015-09-01

Although there are numerous studies suggesting hydrothermal carbonization is an environmentally advantageous process for transformation of wastes to value-added products, a systems level evaluation of the environmental impacts associated with hydrothermal carbonization and subsequent hydrochar combustion has not been conducted. The specific objectives of this work are to use a life cycle assessment approach to evaluate the environmental impacts associated with the HTC of food wastes and the subsequent combustion of the generated solid product (hydrochar) for energy production, and to understand how parameters and/or components associated with food waste carbonization and subsequent hydrochar combustion influence system environmental impact. Results from this analysis indicate that HTC process water emissions and hydrochar combustion most significantly influence system environmental impact, with a net negative GWP impact resulting for all evaluated substituted energy-sources except biomass. These results illustrate the importance of electricity production from hydrochar particularly when it is used to offset coal-based energy sources. HTC process water emissions result in a net impact to the environment, indicating a need for developing appropriate management strategies. Results from this analysis also highlight a need for additional exploration of liquid and gas-phase composition, a better understanding of how changes in carbonization conditions (e.g., reaction time and temperature) influence metal and nutrient fate, and the exploration of liquid-phase treatment. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

NASA Astrophysics Data System (ADS)

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

1981-09-01

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.

Isotopic and trace element geochemistry of the Seligdar magnesiocarbonatites (South Yakutia, Russia): Insights regarding the mantle evolution beneath the Aldan-Stanovoy shield

NASA Astrophysics Data System (ADS)

Doroshkevich, Anna G.; Prokopyev, Ilya R.; Izokh, Andrey E.; Klemd, Reiner; Ponomarchuk, Anton V.; Nikolaeva, Irina V.; Vladykin, Nikolay V.

2018-04-01

The Paleoproterozoic Seligdar magnesiocarbonatite intrusion of the Aldan-Stanovoy shield in Russia underwent extensive postmagmatic hydrothermal alteration and metamorphic events. This study comprises new isotopic (Sr, Nd, C and O) data, whole-rock major and trace element compositions and trace element characteristics of the major minerals to gain a better understanding of the source and the formation process of the carbonatites. The Seligdar carbonatites have high concentrations of P2O5 (up to 18 wt%) and low concentrations of Na, K, Sr and Ba. The chondrite-normalized REE patterns of these carbonatites display significant enrichments of LREE relative to HREE with an average La/Ybcn ratio of 95. Hydrothermal and metamorphic overprints changed the trace element characteristics of the carbonatites and their minerals. These alteration processes were responsible for Sr loss and the shifting of the Sr isotopic compositions towards more radiogenic values. The altered carbonatites are further characterized by distinct 18O- and 13C-enrichments compared to the primary igneous carbonatites. The alteration most likely resulted from both the percolation of crustal-derived hydrothermal fluids and subsequent metamorphic processes accompanied by interaction with limestone-derived CO2. The narrow range of negative εNd(T) values indicates that the Seligdar carbonatites are dominated by a homogenous enriched mantle source component that was separated from the depleted mantle during the Archean.

Sources of Minor and Rare-Earth Elements in Hydrothermal Edifices of Near-Continental Rifts with Sedimentary Cover: Evidence from the Guaymas Basin, Southern Trough

NASA Astrophysics Data System (ADS)

Lein, A. Yu.; Dara, O. M.; Bogdanova, O. Yu.; Novikov, G. V.; Ulyanova, N. V.; Lisitsyn, A. P.

2018-03-01

The mineralogy and geochemistry of a fragment of an active hydrothermal edifice from the Hydrothermal Hill of the Southern Trough valley of the Guaymas Basin in the Gulf of California were studied. The sample was collected from a depth of 1995 m by the Pisces manned submersible on cruise 12 of the R/V Akademik Mstislav Keldysh, Institute of Oceanology, Russian Academy of Sciences. The fragment and the edifice itself consists of two accrete pipes: ore (pyrrhotite) and barren (carbonate) combined in a single edifice by an outer barite-opal zone. The ore edifice is located in the rift zone of the Guaymas Basin with a thick sedimentary cover and is depleted in metals in comparison with ores from rift zones of the open ocean, which are not blocked by sedimentary deposits. This is explained by loss of metals at the boundary between hot sills and sedimentary rocks and by the processes of interaction of hydrothermal solutions with sedimentary deposits. The sedimentary series faciitates long-term preservation of endogenous heat and the ore formation process. Ore edifices of the Guaymas Basin are mostly composed of pyrrhotite, have a specific set of major elements, microelements and REEs, and contain naphthenic hydrocarbons. They may be search signs of hidden polymetallic deposits, considered to be the roots of ore occurrences localized under the surface of the bottom in young active rifts with high spreading and sedimentation rates, i.e., in near-continental areas of rifts of the humid zone with avalanche sedimentation.

Using design of experiments to optimize derivatization with methyl chloroformate for quantitative analysis of the aqueous phase from hydrothermal liquefaction of biomass.

PubMed

Madsen, René Bjerregaard; Jensen, Mads Mørk; Mørup, Anders Juul; Houlberg, Kasper; Christensen, Per Sigaard; Klemmer, Maika; Becker, Jacob; Iversen, Bo Brummerstedt; Glasius, Marianne

2016-03-01

Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R (2)  > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.

Preparation of meta-stable phases of barium titanate by Sol-hydrothermal method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Selvaraj, Mahalakshmi; Department of Material Science, School of Chemistry, Madurai Kamaraj University, Tamilnadu Madurai-625 021; Venkatachalapathy, V.

2015-11-15

Two low-cost chemical methods of sol–gel and the hydrothermal process have been strategically combined to fabricate barium titanate (BaTiO{sub 3}) nanopowders. This method was tested for various synthesis temperatures (100 °C to 250 °C) employing barium dichloride (BaCl{sub 2}) and titanium tetrachloride (TiCl{sub 4}) as precursors and sodium hydroxide (NaOH) as mineralizer for synthesis of BaTiO{sub 3} nanopowders. The as-prepared BaTiO{sub 3} powders were investigated for structural characteristics using x-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The overall analysis indicates that the hydrothermal conditions create a gentle environment to promote the formation of crystalline phasemore » directly from amorphous phase at the very low processing temperatures investigated. XRD analysis showed phase transitions from cubic - tetragonal - orthorhombic - rhombohedral with increasing synthesis temperature and calculated grain sizes were 34 – 38 nm (using the Scherrer formula). SEM and TEM analysis verified that the BaTiO{sub 3} nanopowders synthesized by this method were spherical in shape and about 114 - 170 nm in size. The particle distribution in both SEM and TEM shows that as the reaction temperature increases from 100 °C to 250 °C, the particles agglomerate. Selective area electron diffraction (SAED) shows that the particles are crystalline in nature. The study shows that choosing suitable precursor and optimizing pressure and temperature; different meta-stable (ferroelectric) phases of undoped BaTiO{sub 3} nanopowders can be stabilized by the sol-hydrothermal method.« less

Evidence of a modern deep water magmatic hydrothermal system in the Canary Basin (eastern central Atlantic Ocean)

NASA Astrophysics Data System (ADS)

Medialdea, T.; Somoza, L.; González, F. J.; Vázquez, J. T.; de Ignacio, C.; Sumino, H.; Sánchez-Guillamón, O.; Orihashi, Y.; León, R.; Palomino, D.

2017-08-01

New seismic profiles, bathymetric data, and sediment-rock sampling document for the first time the discovery of hydrothermal vent complexes and volcanic cones at 4800-5200 m depth related to recent volcanic and intrusive activity in an unexplored area of the Canary Basin (Eastern Atlantic Ocean, 500 km west of the Canary Islands). A complex of sill intrusions is imaged on seismic profiles showing saucer-shaped, parallel, or inclined geometries. Three main types of structures are related to these intrusions. Type I consists of cone-shaped depressions developed above inclined sills interpreted as hydrothermal vents. Type II is the most abundant and is represented by isolated or clustered hydrothermal domes bounded by faults rooted at the tips of saucer-shaped sills. Domes are interpreted as seabed expressions of reservoirs of CH4 and CO2-rich fluids formed by degassing and contact metamorphism of organic-rich sediments around sill intrusions. Type III are hydrothermal-volcanic complexes originated above stratified or branched inclined sills connected by a chimney to the seabed volcanic edifice. Parallel sills sourced from the magmatic chimney formed also domes surrounding the volcanic cones. Core and dredges revealed that these volcanoes, which must be among the deepest in the world, are constituted by OIB-type, basanites with an outer ring of blue-green hydrothermal Al-rich smectite muds. Magmatic activity is dated, based on lava samples, at 0.78 ± 0.05 and 1.61 ± 0.09 Ma (K/Ar methods) and on tephra layers within cores at 25-237 ky. The Subvent hydrothermal-volcanic complex constitutes the first modern system reported in deep water oceanic basins related to intraplate hotspot activity.