Moytirra: Discovery of the first known deep-sea hydrothermal vent field on the slow-spreading Mid-Atlantic Ridge north of the Azores

NASA Astrophysics Data System (ADS)

Wheeler, A. J.; Murton, B.; Copley, J.; Lim, A.; Carlsson, J.; Collins, P.; Dorschel, B.; Green, D.; Judge, M.; Nye, V.; Benzie, J.; Antoniacomi, A.; Coughlan, M.; Morris, K.

2013-10-01

Geological, biological, morphological, and hydrochemical data are presented for the newly discovered Moytirra vent field at 45oN. This is the only high temperature hydrothermal vent known between the Azores and Iceland, in the North Atlantic and is located on a slow to ultraslow-spreading mid-ocean ridge uniquely situated on the 300 m high fault scarp of the eastern axial wall, 3.5 km from the axial volcanic ridge crest. Furthermore, the Moytirra vent field is, unusually for tectonically controlled hydrothermal vents systems, basalt hosted and perched midway up on the median valley wall and presumably heated by an off-axis magma chamber. The Moytirra vent field consists of an alignment of four sites of venting, three actively emitting "black smoke," producing a complex of chimneys and beehive diffusers. The largest chimney is 18 m tall and vigorously venting. The vent fauna described here are the only ones documented for the North Atlantic (Azores to Reykjanes Ridge) and significantly expands our knowledge of North Atlantic biodiversity. The surfaces of the vent chimneys are occupied by aggregations of gastropods (Peltospira sp.) and populations of alvinocaridid shrimp (Mirocaris sp. with Rimicaris sp. also present). Other fauna present include bythograeid crabs (Segonzacia sp.) and zoarcid fish (Pachycara sp.), but bathymodiolin mussels and actinostolid anemones were not observed in the vent field. The discovery of the Moytirra vent field therefore expands the known latitudinal distributions of several vent-endemic genera in the north Atlantic, and reveals faunal affinities with vents south of the Azores rather than north of Iceland.

A bestiary of ordinary vent activities at Stromboli (and what it tells us about vent conditions)

NASA Astrophysics Data System (ADS)

Gaudin, Damien; Taddeucci, Jacopo; Scarlato, Piergiorgio

2015-04-01

Normal active degassing at Stromboli (Aeolian Islands, Italy) is traditionally divided in two classes. Puffing correspond to the frequent (~1 Hz) release of small gas pockets (0.5 - 1 m of diameter) at low exit velocities (5 - 15 m/s). Whereas, Strombolian explosions occur at a frequency of 1 - 10 per hour, and are characterized the ejection of bombs and/or ash at high velocities (50 - 400 m/s). In order to get a broader overview of two types of degassing, we used a thermal high speed FLIR SC655 camera to monitor the temperature anomalies generated by the expelled gas, ash, and/or bombs. The enhanced time and spatial resolutions of the camera (200 frames per second, 15 cm wide pixels) enables to use numerical algorithms to distinguish and characterize individual ejection events. In particular, for each explosion and puff, we compute the temperature, the volume, the exit point and the rise velocities of the expelled material. These values, as well as the frequency of the release events, are used to portray a total of 12 vent activities, observed during three field campaigns in 2012, 2013 and 2014. Sustained puffing was visible on 7 cases, with an intensity ranging on at least two orders of magnitude. Although the released gas volume is sometimes highly variable, on some cases, constant sized puffs allows to define a typical discharge frequency ranging between 0.4 and 1.5 Hz. Regular Strombolian explosions, with various duration, intensity and ash contents, are reported in 6 cases, 2 of them simultaneously presenting a puffing activity. In some cases, we noticed modifications of the vent activity just before the explosions. These precursors, usually lasting about 1 second but occasionally reaching 10 seconds, can be sorted into 1) increase of the puffing activity ; 2) emission of gas plumes ; 3) inflation of the visible vent surface. Finally, one vent activity was hybrid between puffing and Strombolian explosions, with frequent explosions (1 Hz) ejecting numerous

First Discovery and Investigation of a High-Temperature Hydrothermal Vent Field on the Ultra- Slow Spreading Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Tao, C.; Lin, J.; Guo, S.; Chen, Y. J.; Wu, G.; Han, X.; German, C. R.; Yoerger, D. R.; Zhu, J.; Zhou, N.; Su, X.; Baker, E. T.; Party, S.

2007-12-01

Two recent cruises on board the Chinese research vessel Dayang Yihao have successfully investigated the first active hydrothermal vent field to be located along the ultraslow spreading Southwest Indian Ridge (SWIR) and collected hydrothermal sulfide deposit samples. The newly discovered hydrothermal vent field is located on the western end of a magmatically robust spreading segment immediately west of the Gallieni transform fault. Preliminary evidence of strong turbidity anomalies was first measured during a Nov. 2005 cruise on board Dayang Yihao (InterRidge News, vol. 15, pp. 33-34, 2006). Color video footages of the seafloor in the vent-field area were first obtained by a deep-towed video camera in February 2007 during DY115-19 Leg 1, when significant water column turbidity anomalies, noticeable temperature anomalies and methane anomalies were also measured. The vent field was then precisely located, mapped, and photographed in great detail in February- March 2007 during the DY115-19 Leg 2, using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution. A high-resolution bathymetric map, more than 5,000 near-bottom color photos, and several types of water column data were all obtained during three phases of ABE dives. Within the approximately 120-m-long by 100-m-wide hydrothermal field, three groups of active high-temperature vents were identified and color images of black smokers and associated biological communities were obtained from ABE, flying 5 m above the seafloor. Hydrothermal sulfide deposits were then successfully obtained using a TV-guided grab.

First Discovery and Investigation of a High-Temperature Hydrothermal Vent Field on the Ultra- Slow Spreading Southwest Indian Ridge

NASA Astrophysics Data System (ADS)

Tao, C.; Lin, J.; Guo, S.; Chen, Y. J.; Wu, G.; Han, X.; German, C. R.; Yoerger, D. R.; Zhu, J.; Zhou, N.; Su, X.; Baker, E. T.; Party, S.

2004-12-01

Two recent cruises on board the Chinese research vessel Dayang Yihao have successfully investigated the first active hydrothermal vent field to be located along the ultraslow spreading Southwest Indian Ridge (SWIR) and collected hydrothermal sulfide deposit samples. The newly discovered hydrothermal vent field is located on the western end of a magmatically robust spreading segment immediately west of the Gallieni transform fault. Preliminary evidence of strong turbidity anomalies was first measured during a Nov. 2005 cruise on board Dayang Yihao (InterRidge News, vol. 15, pp. 33-34, 2006). Color video footages of the seafloor in the vent-field area were first obtained by a deep-towed video camera in February 2007 during DY115-19 Leg 1, when significant water column turbidity anomalies, noticeable temperature anomalies and methane anomalies were also measured. The vent field was then precisely located, mapped, and photographed in great detail in February- March 2007 during the DY115-19 Leg 2, using the autonomous underwater vehicle ABE of the Woods Hole Oceanographic Institution. A high-resolution bathymetric map, more than 5,000 near-bottom color photos, and several types of water column data were all obtained during three phases of ABE dives. Within the approximately 120-m-long by 100-m-wide hydrothermal field, three groups of active high-temperature vents were identified and color images of black smokers and associated biological communities were obtained from ABE, flying 5 m above the seafloor. Hydrothermal sulfide deposits were then successfully obtained using a TV-guided grab.

Deep-water zooplankton of the Guaymas basin hydrothermal vent field

NASA Astrophysics Data System (ADS)

Wiebe, Peter H.; Copley, Nancy; Van Dover, Cindy; Tamse, Armando; Manrique, Fernando

1988-06-01

Zooplankton from the Guaymas Basin deep-sea vent field were collected with a 1 m 2 MOCNESS to examine the distribution of total standing stock, taxonomic composition, size-frequency distribution of zooplankton, and the species composition of calanoid copepods. Low altitude (˜ 100 m above the bottom) horizontal tows along and across the axis of the basin's southern trough, and oblique tows from the bottom of the basin (˜ 2000 m) to the surface were made. Total biomass in near-bottom samples (range: 13-46 cc/1000 m 3) was only about a factor of 10 lower than in the upper 100 m. However, there was little or no evidence for enrichment of biomass in the ˜ 100 m zone above the vent site relative to biomass at the same depth horizon over non-vent areas. Total numbers of individuals ranged between 2600 and 4800/1000 m 3. Calanoid copepods consistently ranked first in abundance of counts of the taxa, followed by cyclopoid copepods, ostracods, chaetognaths, and amphipods. Other less abundant taxa, but in some cases important contributors to total biomass, were coelenterates (siphonophores, medusae), decapod shrimp, and polychaetes. Size-frequency analysis of individuals from each taxon indicated that the biomass and abundance spectra do not fit the theoretically expected spectra based on weight-dependent metabolism and growth. The pyramid of biomass was substantially different from the pyramid of numbers in this deep-sea community. Of the 67 species of copepods identified in two samples taken on low altitude tows, only 15 co-occurred in both samples. Many of the species in this relatively diverse community remain to be described. Larval and post-larval forms of benthic clams, gastropods, polychaetes, and crustaceans associated with the vents were collected 100-200 m above the southern trough, indicating the post-larvae may play an active role in dispersal of hydrothermal vent species.

An off-axis hydrothermal vent field near the Mid-Atlantic Ridge at 30 degrees N.

PubMed

Kelley, D S; Karson, J A; Blackman, D K; Früh-Green, G L; Butterfield, D A; Lilley, M D; Olson, E J; Schrenk, M O; Roe, K K; Lebon, G T; Rivizzigno, P

2001-07-12

Evidence is growing that hydrothermal venting occurs not only along mid-ocean ridges but also on old regions of the oceanic crust away from spreading centres. Here we report the discovery of an extensive hydrothermal field at 30 degrees N near the eastern intersection of the Mid-Atlantic Ridge and the Atlantis fracture zone. The vent field--named 'Lost City'--is distinctly different from all other known sea-floor hydrothermal fields in that it is located on 1.5-Myr-old crust, nearly 15 km from the spreading axis, and may be driven by the heat of exothermic serpentinization reactions between sea water and mantle rocks. It is located on a dome-like massif and is dominated by steep-sided carbonate chimneys, rather than the sulphide structures typical of 'black smoker' hydrothermal fields. We found that vent fluids are relatively cool (40-75 degrees C) and alkaline (pH 9.0-9.8), supporting dense microbial communities that include anaerobic thermophiles. Because the geological characteristics of the Atlantis massif are similar to numerous areas of old crust along the Mid-Atlantic, Indian and Arctic ridges, these results indicate that a much larger portion of the oceanic crust may support hydrothermal activity and microbial life than previously thought.

Pito Seamount revisited: the discovery and mapping of new black smoker vents

NASA Astrophysics Data System (ADS)

Cheadle, M. J.; John, B. E.; German, C. R.; Gee, J. S.; Coogan, L. A.; Gillis, K. M.; Swapp, S.

2017-12-01

In February 2017, the RV Atlantis PMaG (PaleoMagnetism and Gabbro) cruise re-visited a black smoker site originally discovered 24 years ago on Pito Seamount, by the submersible Nautile during the French Pito expedition (1993). Pito Seamount (111.639oW, 23.333oS) marks the northern tip of the propagating East Pacific Rise, bounding the east side of the Easter Microplate. There the seafloor rises to 2250mbsl and has a 900m wide, 50m deep axial valley, which hosts at least two separate fields of active hydrothermal vents. AUV Sentry mapping of the summit of Pito seamount (0.5-1m resolution) highlights over 50 active and inactive chimneys amid recent basaltic sheet flows, pillow mounds and ponded lava. The vents occur in two fields/sub-fields; the first covers an area of 800 x 200m, and lies parallel to the ridge axis, along incipient faults forming on the northeastern flank of the axial valley. The second field occurs in a 250m diameter area in the centre of the axial valley. Jason II dive 961 visited, sampled, measured vent orifice temperatures, and acquired 4k video of the chimneys, and re-discovered the active (Magnificent Village) vent first found by Nautile, in the now named Nautile vent field, together with five additional active hydrothermal vents (Jason, Medea, Sentry, Abe and Scotty's Castle). The Magnificent Village, the largest active vent, is 25m tall and has multiple active spires in three main groups surrounding a hollow amphitheater. Measured vent orifice temperatures ranged from 338oC (Magnificent Village) to 370oC (Jason). The vents host a fauna of alvinellid worms, bythograidid crabs, alvincardid shrimps, phymorhynchus gastropods, Corallimorphid anenomes and bathymodiolid mussels, but no vestimentiferan worms. Brisingid brittle stars colonize inactive chimneys.

Mineralogy and Geochemistry from Trollveggen Vent Field Chimneys and Metalliferous Sediments (Mohns Ridge, West Jan Mayen Fracture Zone at 71°N)

NASA Astrophysics Data System (ADS)

Dias, S.; Cruz, I.; Fonseca, R.; Barriga, F. J.; Pedersen, R.

2010-12-01

The Jan Mayen vent fields were discovered in the Mohns Ridge during an expedition with the Norwegian research vessel "G.O. Sars" in July 2005. They comprise two main active areas: (1) Soria Moria and (2) Gallionella Garden & Trollveggen. The Trollveggen vent field is located at depths of 700-750 m. Venting takes place mainly through white smoker chimneys with fluid temperatures reaching up to 260-270°C. Here we present mineralogical and geochemical data from vent chimneys and metalliferous sediments collected at the Trollveggen vent field with an ROV. Cross-sections of chimneys present evident mineralogical zonation, showing acicular barite crystals in the outer parts and sulfide enrichments in the interior (Sph + Cpy +/- Py - Po). Sediments are mainly formed by vent fragments but also by minerals precipitated by diffuse fluid circulation, showing a mineral assemblage similar to that of chimneys. Microprobe analyses were obtained both in sulfates and sulphides revealing a particular sphalerite composition, characterized by low Fe (< 2%) and high total trace metal contents (up to 4%, including Cu, Ag and Au). Geochemical profiles of gravity cores collected in the area surrounding Jan Mayen were also performed in order to investigate the presence of additional hydrothermal activity in the area. Total geochemical analyses showed a slight enrichment in trace metals, such as Cu, Zn and Fe, with exception of one core that reached 85 ppm for Cu, 150 ppm for Zn and 20% for Fe. The metal enrichment in this core suggests hydrothermal activity in the neighboring area.

Loki's Castle: Discovery and geology of a black smoker vent field at the Arctic Mid-Ocean Ridge

NASA Astrophysics Data System (ADS)

Pedersen, R.; Thorseth, I. H.; Lilley, M. D.; Barriga, F. J.; Früh-Green, G.; Nakamura, K.

2010-12-01

Previous attempts to locate hydrothermal vent fields and unravel the nature of venting at the ultraslow spreading and magma starved parts of the Arctic Mid Ocean Ridge (AMOR) have been unsuccessful. A black smoker vent field was eventually discovered at the Mohns-Knipovich bend at 73.5°N in 2008, and the field was revisited in 2009 and 2010. The Loki’s Castle vent field is located on the crest of an axial volcanic ridge that is bordered by a tectonic terrain dominated by core complexes to the NW, and a ridge flank that is buried by sediments from the Bear Island Fan to the SE. Fluid compositions are anomalous to other basalt-hosted fields and indicate interactions with sediments at depths. The vent field is associated with an unusually large hydrothermal deposit, which documents that extensive venting occurs at ultraslow spreading ridges despite the strongly reduced magmatic heat budget. ROV surveys have shown that venting occurs in two areas separated by around 100 m. Micro-bathymetry acquired by a Hugin AUV documents that two 20-30 tall mounds that coalesce at the base have developed around the vent sites. The micro-bathymetry also shows that the venting is located above two normal faults that define the NW margin of a rift that runs along the crest of the volcano. The black smoker fluids reach 317 °C, with an end-member SiO2 content of 16 mmol/kg. End-member chlorinity is around 85% of seawater suggesting that the fluids have phase-separated at depth. The fluid compositions indicate that the rock-water reactions occur around 2 km below the seafloor. The crustal thickness is estimated to be 4 +/- 0.5 km in the area. Whereas the depth of the reaction zone is comparable with faster spreading ridges, the fraction of crust cooled convectively by hydrothermal circulation is two times that of vent fields at ridges with normal crustal thickness.

Spatial and Alignment Analyses for a field of Small Volcanic Vents South of Pavonis Mons Mars

NASA Technical Reports Server (NTRS)

Bleacher, J. E.; Glaze, L. S.; Greeley, R.; Hauber, E.; Baloga, S. M.; Sakimoto, S. E. H.; Williams, D. A.; Glotch, T. D.

2008-01-01

The Tharsis province of Mars displays a variety of small volcanic vent (10s krn in diameter) morphologies. These features were identified in Mariner and Viking images [1-4], and Mars Orbiter Laser Altimeter (MOLA) data show them to be more abundant than originally observed [5,6]. Recent studies are classifying their diverse morphologies [7-9]. Building on this work, we are mapping the location of small volcanic vents (small-vents) in the Tharsis province using MOLA, Thermal Emission Imaging System, and High Resolution Stereo Camera data [10]. Here we report on a preliminary study of the spatial and alignment relationships between small-vents south of Pavonis Mons, as determined by nearest neighbor and two-point azimuth statistical analyses. Terrestrial monogenetic volcanic fields display four fundamental characteristics: 1) recurrence rates of eruptions,2 ) vent abundance, 3) vent distribution, and 4) tectonic relationships [11]. While understanding recurrence rates typically requires field measurements, insight into vent abundance, distribution, and tectonic relationships can be established by mapping of remotely sensed data, and subsequent application of spatial statistical studies [11,12], the goal of which is to link the distribution of vents to causal processes.

Metal interactions between the polychaete Branchipolynoe seepensis and the mussel Bathymodiolus azoricus from Mid-Atlantic-Ridge hydrothermal vent fields.

PubMed

Bebianno, Maria João; Cardoso, Cátia; Gomes, Tânia; Blasco, Julian; Santos, Ricardo Serrão; Colaço, Ana

2018-04-01

The vent blood-red commensal polynoid polychaete Branchipolynoe seepensis is commonly found in the pallial cavity of the vent mussel Bathymodiolus azoricus, the dominant bivalve species along the Mid-Atlantic-Ridge (MAR) and is known to be kleptoparasitic. Mussels were collected from three hydrothermal vent fields in the MAR: Menez Gwen (850 m depth, MG2, MG3 and MG4), Lucky Strike (1700 m depth, Montségur-MS and Eiffel Tower-ET) and Rainbow (2300 m depth). Polychaetes were absent in all Menez Gwen vent mussels, while the highest percentage was detected in mussels from Lucky Strike, where more than 70% of the mussels had at least one polychaete in their mantle cavity, followed by Rainbow with 33% of mussels with polychaetes. Total metal concentrations (Ag, Cd, Co, Cu, Fe, Mn, Ni and Zn) were determined in polychaetes whole body and in the mussel tissues (gills, digestive gland and mantle). To understand the possible metal interactions between symbiont and host, the activity of antioxidant defence (catalase (CAT), metallothioneins (MTs)), biotransformation enzymes (glutathione-s-transferases (GST)) activities and lipid peroxidation (LPO) were determined in polychaete whole soft tissues and in mussel tissues (gills, digestive gland and mantle). Metal concentrations in polychaetes and mussels tissues indicated that the accumulation patterns were species specific and also influenced by, and possibly dependent upon, the inter- and intra-variation of vent physico-chemistry between hydrothermal fields. Despite not detecting any strong correlations between metal and enzymes activities in polychaetes and mussels, when in presence of polychaetes, mussels presented less metal concentrations in the gills and digestive gland and lower activity of enzymatic biomarkers. This leads to infer that the polychaete plays a role on the detoxification process, and the interaction between the polychaete mussel association is probably an adaptation to metals concentrations at the

A Geophysical Model for the Origin of Volcano Vent Clusters in a Colorado Plateau Volcanic Field

NASA Astrophysics Data System (ADS)

Deng, Fanghui; Connor, Charles B.; Malservisi, Rocco; Connor, Laura J.; White, Jeremy T.; Germa, Aurelie; Wetmore, Paul H.

2017-11-01

Variation in spatial density of Quaternary volcanic vents, and the occurrence of vent clusters, correlates with boundaries in Proterozoic crust in the Springerville volcanic field (SVF), Arizona, USA. Inverse modeling using 538 gravity measurements shows that vent clusters correlate with gradients in the gravity field due to lateral variation in crustal density. These lateral discontinuities in the crustal density can be explained by boundaries in the North American crust formed during Proterozoic accretion. Spatial density of volcanic vents is low in regions of high-density Proterozoic crust, high in areas of relatively low density Proterozoic crust, and is greatest adjacent to crustal boundaries. Vent alignments parallel these boundaries. We have developed 2-D and 3-D numerical models of magma ascent through the crust to simulate long-term, average magma migration that led to the development of vent clusters in the SVF, assuming that a viscous fluid flow through a porous media is statistically equivalent to magma migration averaged over geological time in the full field scale. The location and flux from the uniform magma source region are boundary conditions of the model. Changes in model diffusivity, associated with changes in the bulk properties of the lithosphere, can simulate preferential magma migration paths and alter estimated magma flux at the surface, implying that large-scale crustal structures, such as inherited tectonic block boundaries, influence magma ascent and clustering of volcanic vents. Probabilistic models of volcanic hazard for distributed volcanic fields can be improved by identifying crustal structures and assessing their impact on volcano distribution with the use of numerical models.

Estimating the Total Heat Flux from the ASHES Hydrothermal Vent Field Using the Sentry Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Crone, T. J.; Kinsey, J. C.; Mittelstaedt, E. L.

2017-12-01

Hydrothermal venting at mid-ocean ridges influences ocean chemistry, the thermal and chemical structure of the oceanic crust, and the evolution of unique and diverse autolithotrophically-supported ecosystems. Axially-hosted hydrothermal systems are responsible for 20-25% of the total heat flux out of Earth's interior, and likely play a large role in local as well as global biogeochemical cycles. Despite the importance of these systems, only a few studies have attempted to constrain the volume and heat flux of an entire hydrothermal vent field. In July of 2014 we used the Sentry autonomous underwater vehicle (AUV) to survey the water column over the ASHES hydrothermal vent field which is located within the caldera of Axial Seamount, an active submarine volcano located on the Juan de Fuca Ridge. To estimate the total heat and mass flux from this vent field, we equipped Sentry with a Nortek acoustic Doppler velocimeter (ADV), an inertial measurement unit (IMU), two acoustic Doppler current profilers (ADCPs), and two SBE3 temperature probes, allowing us to obtain precise measurements of fluid temperature and water velocity. The survey was designed using a control volume approach in which Sentry was pre-programmed to survey a 150-m-square centered over the vent field flying a grid pattern with 5-m track line spacing followed by a survey of the perimeter. This pattern was repeated multiple times during several 10-h dives at different altitudes, including 10, 20, 40, and 60 m above the seafloor, and during one 40-h survey at an altitude of 10 m. During the 40-h survey, the pattern was repeated nine times allowing us to obtain observations over several tidal cycles. Water velocity data obtained with Sentry were corrected for platform motion and then combined with the temperature measurements to estimate heat flux. The analysis of these data will likely provide the most accurate and highest resolution heat and mass flux estimates at a seafloor hydrothermal field to date.

The roar of Yasur: Handheld audio recorder monitoring of Vanuatu volcanic vent activity

NASA Astrophysics Data System (ADS)

Lorenz, Ralph D.; Turtle, Elizabeth P.; Howell, Robert; Radebaugh, Jani; Lopes, Rosaly M. C.

2016-08-01

We describe how near-field audio recording using a pocket digital sound recorder can usefully document volcanic activity, demonstrating the approach at Yasur, Vanuatu in May 2014. Prominent emissions peak at 263 Hz, interpreted as an organ-pipe mode. High-pass filtering was found to usefully discriminate volcano vent noise from wind noise, and autocorrelation of the high pass acoustic power reveals a prominent peak in exhalation intervals of 2.5, 4 and 8 s, with a number of larger explosive events at 200 s intervals. We suggest that this compact and inexpensive audio instrumentation can usefully supplement other field monitoring such as seismic or infrasound. A simple estimate of acoustic power interpreted with a dipole jet noise model yielded vent velocities too low to be compatible with pyroclast emission, suggesting difficulties with this approach at audio frequencies (perhaps due to acoustic absorption by volcanic gases).

Physiological impacts of acute Cu exposure on deep-sea vent mussel Bathymodiolus azoricus under a deep-sea mining activity scenario.

PubMed

Martins, Inês; Goulart, Joana; Martins, Eva; Morales-Román, Rosa; Marín, Sergio; Riou, Virginie; Colaço, Ana; Bettencourt, Raul

2017-12-01

Over the past years, several studies have been dedicated to understanding the physiological ability of the vent mussel Bathymodiolus azoricus to overcome the high metal concentrations present in their surrounding hydrothermal environment. Potential deep-sea mining activities at Azores Triple junction hydrothermal vent deposits would inevitably lead to the emergence of new fluid sources close to mussel beds, with consequent emission of high metal concentrations and potential resolubilization of Cu from minerals formed during the active phase of the vent field. Copper is an essential metal playing a key role in the activation of metalloenzymes and metalloproteins responsible for important cellular metabolic processes and tissue homeostasis. However, excessive intracellular amounts of reactive Cu ions may cause irreversible damages triggering possible cell apoptosis. In the present study, B. azoricus was exposed to increasing concentrations of Cu for 96h in conditions of temperature and hydrostatic pressure similar to those experienced at the Lucky Strike hydrothermal vent field. Specimens were kept in 1L flasks, exposed to four Cu concentrations: 0μg/L (control), 300, 800 and 1600μg/L and pressurized to 1750bar. We addressed the question of how increased Cu concentration would affect the function of antioxidant defense proteins and expression of antioxidant and immune-related genes in B. azoricus. Both antioxidant enzymatic activities and gene expression were examined in gills, mantle and digestive gland tissues of exposed vent mussels. Our study reveals that stressful short-term Cu exposure has a strong effect on molecular metabolism of the hydrothermal vent mussel, especially in gill tissue. Initially, both the stress caused by unpressurization or by Cu exposure was associated with high antioxidant enzyme activities and tissue-specific transcriptional up-regulation. However, mussels exposed to increased Cu concentrations showed both antioxidant and immune

Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity

PubMed Central

Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B.; Rouse, Greg; Salcedo, Diana L.; Soto, Luis A.; Zierenberg, Robert; Vrijenhoek, Robert

2017-01-01

Hydrothermal vent communities are distributed along mid-ocean spreading ridges as isolated patches. While distance is a key factor influencing connectivity among sites, habitat characteristics are also critical. The Pescadero Basin (PB) and Alarcón Rise (AR) vent fields, recently discovered in the southern Gulf of California, are bounded by previously known vent localities (e.g. Guaymas Basin and 21° N East Pacific Rise); yet, the newly discovered vents differ markedly in substrata and vent fluid attributes. Out of 116 macrofaunal species observed or collected, only three species are shared among all four vent fields, while 73 occur at only one locality. Foundation species at basalt-hosted sulfide chimneys on the AR differ from the functional equivalents inhabiting sediment-hosted carbonate chimneys in the PB, only 75 km away. The dominant species of symbiont-hosting tubeworms and clams, and peripheral suspension-feeding taxa, differ between the sites. Notably, the PB vents host a limited and specialized fauna in which 17 of 26 species are unknown at other regional vents and many are new species. Rare sightings and captured larvae of the ‘missing’ species revealed that dispersal limitation is not responsible for differences in community composition at the neighbouring vent localities. Instead, larval recruitment-limiting habitat suitability probably favours species differentially. As scenarios develop to design conservation strategies around mining of seafloor sulfide deposits, these results illustrate that models encompassing habitat characteristics are needed to predict metacommunity structure. PMID:28724734

Hydrothermal vent fields discovered in the southern Gulf of California clarify role of habitat in augmenting regional diversity.

PubMed

Goffredi, Shana K; Johnson, Shannon; Tunnicliffe, Verena; Caress, David; Clague, David; Escobar, Elva; Lundsten, Lonny; Paduan, Jennifer B; Rouse, Greg; Salcedo, Diana L; Soto, Luis A; Spelz-Madero, Ronald; Zierenberg, Robert; Vrijenhoek, Robert

2017-07-26

Hydrothermal vent communities are distributed along mid-ocean spreading ridges as isolated patches. While distance is a key factor influencing connectivity among sites, habitat characteristics are also critical. The Pescadero Basin (PB) and Alarcón Rise (AR) vent fields, recently discovered in the southern Gulf of California, are bounded by previously known vent localities (e.g. Guaymas Basin and 21° N East Pacific Rise); yet, the newly discovered vents differ markedly in substrata and vent fluid attributes. Out of 116 macrofaunal species observed or collected, only three species are shared among all four vent fields, while 73 occur at only one locality. Foundation species at basalt-hosted sulfide chimneys on the AR differ from the functional equivalents inhabiting sediment-hosted carbonate chimneys in the PB, only 75 km away. The dominant species of symbiont-hosting tubeworms and clams, and peripheral suspension-feeding taxa, differ between the sites. Notably, the PB vents host a limited and specialized fauna in which 17 of 26 species are unknown at other regional vents and many are new species. Rare sightings and captured larvae of the 'missing' species revealed that dispersal limitation is not responsible for differences in community composition at the neighbouring vent localities. Instead, larval recruitment-limiting habitat suitability probably favours species differentially. As scenarios develop to design conservation strategies around mining of seafloor sulfide deposits, these results illustrate that models encompassing habitat characteristics are needed to predict metacommunity structure. © 2017 The Authors.

High Connectivity of Animal Populations in Deep-Sea Hydrothermal Vent Fields in the Central Indian Ridge Relevant to Its Geological Setting

PubMed Central

Beedessee, Girish; Watanabe, Hiromi; Ogura, Tomomi; Nemoto, Suguru; Yahagi, Takuya; Nakagawa, Satoshi; Nakamura, Kentaro; Takai, Ken; Koonjul, Meera; Marie, Daniel E. P.

2013-01-01

Dispersal ability plays a key role in the maintenance of species in spatially and temporally discrete niches of deep-sea hydrothermal vent environments. On the basis of population genetic analyses in the eastern Pacific vent fields, dispersal of animals in the mid-oceanic ridge systems generally appears to be constrained by geographical barriers such as trenches, transform faults, and microplates. Four hydrothermal vent fields (the Kairei and Edmond fields near the Rodriguez Triple Junction, and the Dodo and Solitaire fields in the Central Indian Ridge) have been discovered in the mid-oceanic ridge system of the Indian Ocean. In the present study, we monitored the dispersal of four representative animals, Austinograea rodriguezensis, Rimicaris kairei, Alviniconcha and the scaly-foot gastropods, among these vent fields by using indirect methods, i.e., phylogenetic and population genetic analyses. For all four investigated species, we estimated potentially high connectivity, i.e., no genetic difference among the populations present in vent fields located several thousands of kilometers apart; however, the direction of migration appeared to differ among the species, probably because of different dispersal strategies. Comparison of the intermediate-spreading Central Indian Ridge with the fast-spreading East Pacific Rise and slow-spreading Mid-Atlantic Ridge revealed the presence of relatively high connectivity in the intermediate- and slow-spreading ridge systems. We propose that geological background, such as spreading rate which determines distance among vent fields, is related to the larval dispersal and population establishment of vent-endemic animal species, and may play an important role in controlling connectivity among populations within a biogeographical province. PMID:24358117

Detecting deep sea hydrothermal vents with a split-beam echosounder

NASA Astrophysics Data System (ADS)

Gray, L. M.; Jerram, K.

2016-12-01

In May 2016, the NOAA Office of Exploration and Research exploration vessel, Okeanos Explorer, conducted a remotely operated vehicle (ROV) dive on a series of active `black smoker' hydrothermal vents at 3,300 m depth in the western Pacific Ocean near the Mariana Trench. The ROV system traversed 800 m along the seafloor and detected three distinct vent sites. The vent chimneys ranged in heights from 5 m to 30 m above the seafloor and vent fluid temperatures were measured as high as 337 °C. Immediately following the ROV dive, the Okeanos Explorer mapped the vent field with an 18 kHz split-beam echosounder traditionally used for fishery research and a 30 kHz multibeam echosounder with midwater capability. Six passes were made over the field, transiting at 4-5 knots on various headings. There was a clear and repeatable signal in the split-beam echogram from the venting but less obvious indication in the multibeam data. `Black smokers' have traditionally been detected using repeat conductivity-temperature-depth (CTD) `tow-yo' casts. Our field observations suggest an alternative, and potentially more efficient, method of detecting hydrothermal vent plumes within the beamwidth of the split-beam echosounder to inform ROV dive plans. Methods previously applied for locating marine gas seeps on the seafloor with split-beam echosounders can be applied to estimate the hydrothermal vent positions in this dataset and compared to the recorded ROV positions at each site. Additionally, assuming relatively stable venting and ambient conditions, the ROV position and CTD data recorded from the vehicles can be used to better understand the observed midwater acoustic backscatter signatures of the hydrothermal vent plumes.

Metaproteogenomic Profiling of Microbial Communities Colonizing Actively Venting Hydrothermal Chimneys

PubMed Central

Pjevac, Petra; Meier, Dimitri V.; Markert, Stephanie; Hentschker, Christian; Schweder, Thomas; Becher, Dörte; Gruber-Vodicka, Harald R.; Richter, Michael; Bach, Wolfgang; Amann, Rudolf; Meyerdierks, Anke

2018-01-01

At hydrothermal vent sites, chimneys consisting of sulfides, sulfates, and oxides are formed upon contact of reduced hydrothermal fluids with oxygenated seawater. The walls and surfaces of these chimneys are an important habitat for vent-associated microorganisms. We used community proteogenomics to investigate and compare the composition, metabolic potential and relative in situ protein abundance of microbial communities colonizing two actively venting hydrothermal chimneys from the Manus Basin back-arc spreading center (Papua New Guinea). We identified overlaps in the in situ functional profiles of both chimneys, despite differences in microbial community composition and venting regime. Carbon fixation on both chimneys seems to have been primarily mediated through the reverse tricarboxylic acid cycle and fueled by sulfur-oxidation, while the abundant metabolic potential for hydrogen oxidation and carbon fixation via the Calvin–Benson–Bassham cycle was hardly utilized. Notably, the highly diverse microbial community colonizing the analyzed black smoker chimney had a highly redundant metabolic potential. In contrast, the considerably less diverse community colonizing the diffusely venting chimney displayed a higher metabolic versatility. An increased diversity on the phylogenetic level is thus not directly linked to an increased metabolic diversity in microbial communities that colonize hydrothermal chimneys. PMID:29696004

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

Mapping the Active Vents of Stromboli Volcano with an Unmanned Aerial Vehicle

NASA Astrophysics Data System (ADS)

Turner, N.; Houghton, B. F.; von der Lieth, J.; Hort, M. K.; Taddeucci, J.; Kueppers, U.; Ricci, T.; Gaudin, D.

2016-12-01

We present a new detailed map of the active vents of Stromboli volcano obtained from UAV flights in May 2016, when the active NE and SW craters were repeatedly mapped. Due to high levels of gas emissions and frequent explosions, fine-scale measurements of vent geometry from single flights were challenging. However, the compilation of data acquired over 12 flights used with Structure from Motion software allowed us to create a 10 cm Digital Elevation Model (DEM) offering a non-obstructed view into the active craters. Such direct observations permits us to constrain parameters such as vent geometry and depth with an unprecedented precision, thus potentially reducing the uncertainty of models depending on such inputs (e.g. conduit and acoustic models). Furthermore, the low-cost and safety of UAVs allows mapping changes at small temporal and spatial resolutions, making this technique complementary to monitoring efforts at active volcanoes.

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

Spatial and Alignment Analyses for a Field of Small Volcanic Vents South of Pavonis Mons and Implications for the Tharsis Province, Mars

NASA Technical Reports Server (NTRS)

Bleacher, Jacob E.; Glaze, Lori S.; Greeley, Ronald; Hauber, Ernst; Baloga, Stephen; Sakimoto, Susan E. H.; Williams, David A.; Glotch, Timothy D.

2009-01-01

A field of small volcanic vents south of Pavonis Mons was mapped with each vent assigned a two-dimensional data point. Nearest neighbor and two-point azimuth analyses were applied to the resulting location data. Nearest neighbor results show that vents within this field are spatially random in a Poisson sense, suggesting that the vents formed independently of each other without sharing a centralized magma source at shallow depth. Two-point azimuth results show that the vents display north-trending alignment relationships between one another. This trend corresponds to the trends of faults and fractures of the Noachian-aged Claritas Fossae, which might extend into our study area buried beneath more recently emplaced lava flows. However, individual elongate vent summit structures do not consistently display the same trend. The development of the volcanic field appears to display tectonic control from buried Noachian-aged structural patterns on small, ascending magma bodies while the surface orientations of the linear vents might reflect different, younger tectonic patterns. These results suggest a complex interaction between magma ascension through the crust, and multiple, older, buried Tharsis-related tectonic structures.

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

Temporal and spatial variation in temperature experienced by macrofauna at Main Endeavour hydrothermal vent field

NASA Astrophysics Data System (ADS)

Lee, Raymond W.; Robert, Katleen; Matabos, Marjolaine; Bates, Amanda E.; Juniper, S. Kim

2015-12-01

A significant focus of hydrothermal vent ecological studies has been to understand how species cope with various stressors through physiological tolerance and biochemical resistance. Yet, the environmental conditions experienced by vent species have not been well characterized. This objective requires continuous observations over time intervals that can capture environmental variability at scales that are relevant to animals. We used autonomous temperature logger arrays (four roughly parallel linear arrays of 12 loggers spaced every 10-12 cm) to study spatial and temporal variations in the thermal regime experienced by hydrothermal vent macrofauna at a diffuse flow vent. Hourly temperatures were recorded over eight months from 2010 to 2011 at Grotto vent in the Main Endeavour vent field on the Juan de Fuca Ridge, a focus area of the Ocean Networks Canada cabled observatory. The conspicuous animal assemblages in video footage contained Ridgeia piscesae tubeworms, gastropods (primarily Lepetodrilus fucensis), and polychaetes (polynoid scaleworms and the palm worm Paralvinella palmiformis). Two dimensional spatial gradients in temperature were generally stable over the deployment period. The average temperature recorded by all arrays, and in some individual loggers, revealed distinctive fluctuations in temperature that often corresponded with the tidal cycle. We postulate that this may be related to changes in bottom currents or fluctuations in vent discharge. A marked transient temperature increase lasting over a period of days was observed in April 2011. While the distributions and behavior of Juan de Fuca Ridge vent invertebrates may be partially constrained by environmental temperature and temperature tolerance, except for the one transient high-temperature event, observed fluid temperatures were generally similar to the thermal preferences for some species, and typically well below lethal temperatures for all species. Average temperatures of the four arrays

Field Testing of an Unvented Roof with Fibrous Insulation, Tiles, and Vapor Diffusion Venting

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

Ueno, K.; Lstiburek, J. W.

This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane.more » As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design.« less

Extensive deep-sea dispersal of postlarval shrimp from a hydrothermal vent

NASA Astrophysics Data System (ADS)

Herring, P. J.; Dixon, D. R.

1998-12-01

Hydrothermal vent fields on the Mid-Atlantic Ridge (MAR) are small (no more than 0.1-1.0 km 2) and widely spaced (a reported average of one field per 175 km between 11°N and 40°N). Their faunas are similar and usually dominated by shrimp of the family Bresiliidae. Little is known about the way these animals (and other members of the vent fauna) disperse and colonize new vents. Vent shrimp juveniles have been taken close to certain vent sites, and in midwater, but their larvae and postlarvae have not been captured. We report here that bresiliid shrimp postlarvae are very widely dispersed around the Broken Spur vent field and extend into the next MAR segment and the Atlantis Fracture Zone beyond. The populations show density gradients declining both vertically and horizontally from the vent site, in contrast to the overall pelagic biomass. This is the furthest recorded dispersal (>100 km) of identified larvae from a hydrothermal vent and is sufficient to give them access to adjacent vent fields and thus the scope for colonising new sites.

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2013 CFR

2013-04-01

...) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 11/2 inch... venting cross section of a 11/2 inch diameter vent, connected to the toilet drain by one of the following... toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in size...

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2012 CFR

2012-04-01

...) Size of vent piping—(1) Main vent. The drain piping for each toilet shall be vented by a 11/2 inch... venting cross section of a 11/2 inch diameter vent, connected to the toilet drain by one of the following... toilet drain within the distance allowed in § 3280.611(c)(5), for 3-inch trap arms undiminished in size...

Noble Gas geochemistry of the newly discovered hydrothermal fields in the Gulf of California: preliminary He-isotope ratios from the Alarcon Rise and Pescadero basin vent sites

NASA Astrophysics Data System (ADS)

Spelz, R. M.; Lupton, J. E.; Evans, L. J.; Zierenberg, R. A.; Clague, D. A.; Neumann, F.; Paduan, J. B.

2015-12-01

Numerous submarine deep-sea hydrothermal vents related to volcanic activity of the East Pacific Rise (EPR) are situated along the Pacific margins of Mexico. Until recently, active hydrothermal venting was unknown between the Guaymas Basin and 21°N on the EPR. MBARI's recent oceanographic surveys have added 7 new active vent sites. In this study, we aimed to sample the high-temperature hydrothermal fluids emanating from two distinct vent sites, named Meyibo and Auka, located in the Alarcon Rise and Pescadero Basin, respectively. Mantle-derived He have long been identified in hydrothermal fluid releases. The presence of He in aqueous fluids with 3He/4He ratios greater than in-situ production values (~0.05 RA, where RA = air He or 1.4 x 10-6) indicates the presence of mantle-derived melts. Preliminary analyses of He-isotope ratios derived from the newly discovered Meyibo and Auka hydrothermal fields show high 3He/4He ratios (~8RA), typical of MORB's. Auka vent field, characterized by chimneys composed of light carbonate minerals and oil-like hydrocarbons, and temperatures between 250-290oC, show average values of ~7.87RA. In contrast, the black-smokers at the Meyibo field, composed of dark sulfide minerals and temperatures over 350oC, yielded a higher He ratio of ~8.24RA. Recently, it has become clear that regional maximum mantle He values correlate with the velocity structure in the mantle, therefore, He has the potential to map regions of the underlying mantle that are undergoing partial melting. Seismic records could then be compared with the geochemical He ratio signal and supply information regarding tectonics and other processes involved in the generation of these gases. The data presented here will be completing a totally new inventory of He results from hydrothermal vents in the EPR and fault-termination basins distributed along the P-NA plate boundary in the Gulf of California. The results will be further coupled with the analysis of other geochemical

Novel Barite Chimneys at the Loki's Castle Vent Field Shed Light on Key Factors Shaping Microbial Communities and Functions in Hydrothermal Systems.

PubMed

Steen, Ida H; Dahle, Håkon; Stokke, Runar; Roalkvam, Irene; Daae, Frida-Lise; Rapp, Hans Tore; Pedersen, Rolf B; Thorseth, Ingunn H

2015-01-01

In order to fully understand the cycling of elements in hydrothermal systems it is critical to understand intra-field variations in geochemical and microbiological processes in both focused, high-temperature and diffuse, low-temperature areas. To reveal important causes and effects of this variation, we performed an extensive chemical and microbiological characterization of a low-temperature venting area in the Loki's Castle Vent Field (LCVF). This area, located at the flank of the large sulfide mound, is characterized by numerous chimney-like barite (BaSO4) structures (≤ 1 m high) covered with white cotton-like microbial mats. Results from geochemical analyses, microscopy (FISH, SEM), 16S rRNA gene amplicon-sequencing and metatranscriptomics were compared to results from previous analyses of biofilms growing on black smoker chimneys at LCVF. Based on our results, we constructed a conceptual model involving the geochemistry and microbiology in the LCVF. The model suggests that CH4 and H2S are important electron donors for microorganisms in both high-temperature and low-temperature areas, whereas the utilization of H2 seems restricted to high-temperature areas. This further implies that sub-seafloor processes can affect energy-landscapes, elemental cycling, and the metabolic activity of primary producers on the seafloor. In the cotton-like microbial mats on top of the active barite chimneys, a unique network of single cells of Epsilonproteobacteria interconnected by threads of extracellular polymeric substances (EPS) was seen, differing significantly from the long filamentous Sulfurovum filaments observed in biofilms on the black smokers. This network also induced nucleation of barite crystals and is suggested to play an essential role in the formation of the microbial mats and the chimneys. Furthermore, it illustrates variations in how different genera of Epsilonproteobacteria colonize and position cells in different vent fluid mixing zones within a vent field

Distribution and chemistry of suspended particles from an active hydrothermal vent site on the Mid-Atlantic Ridge at 26°N

NASA Astrophysics Data System (ADS)

Trocine, Robert P.; Trefry, John H.

1988-04-01

Suspended particles were collected from an area of active hydrothermal venting at the Trans-Atlantic Geotraverse (TAG) Hydrothermal Field on the Mid-Atlantic Ridge and analyzed for Fe, Mn, Cd, Zn, Cu, V, Ni, Cr, Pb, Mg, Ca, Al and Si. Rapid advection of vent-derived precipitates produced a lens with total suspended matter (TSM) loadings of 14-60 μg/l at 200-700 m above the seafloor; TSM concentrations > 60 μg/l were observed only at near-vent sites. The distribution of suspended particles correlated well with increased dissolved Mn concentrations and particulate Fe values near the vent source. Particulate Fe values decreased linearly relative to TSM concentrations as hydrothermal precipitates mixed with background suspended matter. Near-vent precipitates were characterized by up to 35% Fe, 2% Zn, 0.6% Cu and > 100 μg/g Cd. In comparison to Fe, particulate Cd, Zn and Cu values decreased dramatically away from the vent source. This trend supports differential settling and/or dissolution of Cd-, Zn- and Cu-bearing phases. Particulate Mn and Fe values were inversely related with only 50 μg Mn/g in the near-vent particles. At near-vent sites, > 99% of the total Mn was in solution; this fraction decreased to 75-80% at background TSM values. In contrast to Cd, Zn and Cu, particulate V levels show a continuous, linear decrease with particulate Fe values. This trend is explained by adsorption of V on Fe-oxides in the vent plume. Scavenging of Cr, Pb and Mg by hydrothermal precipitates is also suggested by the data. Nickel and Al values were low in near-vent particles at < 100 and < 3 μg/g, respectively. The complementary behavior of dissolved Mn and particulate trace metals provides a useful framework for studying broad aspects of hydrothermal plume processes.

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

Chemosynthetic microbial activity at Mid-Atlantic Ridge hydrothermal vent sites

NASA Astrophysics Data System (ADS)

Wirsen, Carl O.; Jannasch, Holger W.; Molyneaux, Stephen J.

1993-06-01

Chemosynthetic production of microbial biomass, determined by 14CO2 fixation and enzymatic (RuBisCo) activity, at the Mid-Atlantic Ridge (MAR) 23° and 26°N vent sites was found in various niches: warm water emissions, loosely rock-attached flocculent material, dense morphologically diverse bacterial mats covering the surfaces of polymetal sulfide deposits, and filamentous microbes on the carapaces of shrimp (Rimicaris exoculata). The bacterial mats on polymetal sulfide surfaces contained unicellular and filamentous bacteria which appeared to use as their chemolithotrophic electron or energy source either dissolved reduced minerals from vent emissions, mainly sulfur compounds, or solid metal sulfide deposits, mainly pyrite. Moderately thermophilic Chemosynthetic activity was observed in carbon dioxide fixation experiments and in enrichments, but no thermophilic aerobic sulfur oxidizers could be isolated. Both obligate and facultative chemoautotrophs growing at mesophilic temperatures were isolated from all chemosynthetically active surface scrapings. The obligate autotrophs could oxidize sterilized MAR natural sulfide deposits as well as technical pyrite at near neutral pH, in addition to dissolved reduced sulfur compounds. While the grazing by shrimp on the surface mats of MAR metal sulfide deposits was observed and deemed important, the animals' primary occurrence in dense swarms near vent emissions suggests that they were feeding at these sites, where conditions for Chemosynthetic growth of their filamentous microbial epiflora were optimal. The data show that the transformation of geothermal energy at the massive polymetal sulfide deposits of the MAR is based on the lithoautotrophic oxidation of soluble sulfides and pyrites into microbial biomass.

Fluid Geochemistry of the Capelinhos Vent Site. A Key to Understand the Lucky Strike Hydrothermal Vent Field (37°N, MAR).

NASA Astrophysics Data System (ADS)

Leleu, T.; Chavagnac, V.; Cannat, M.; Ceuleneer, G.; Castillo, A.; Menjot, L.

2015-12-01

The Lucky Strike hydrothermal field is situated at the mid-Atlantic ridge, south of the Azores, on top of a central volcano within the axial valley. The volcano is composed of a fossil lava lake surrounded by three volcanic cones. An Axial Magma Chamber (AMC) is reported 3.4km below the seafloor. The active venting sites are situated around the fossil lava lake and are directly linked to the heat supplied by the AMC. High temperature fluids from the Lucky Strike field were sampled in 2013, 2014 and 2015 in order to document the depth of the reaction zone, subsurface mixing, geographical control and magmatic degassing. A new active site named Capelinhos was discovered approximately 1.5km eastward from the lava lake, during exploration by ROV Victor6000 - MoMARsat cruise, 2013. It is composed of 10m-high chimneys discharging black smoker-type fluid. Fluid temperatures were 328°C in 2013 and decreased to 318°C in 2014 and 2015. Capelinhos fluids are Cl-depleted by 55% compared to seawater indicating phase separation at depth. In comparison, the other sites range from 6% enrichment (2608/Y3 site) to 22% depletion (Eiffel tower site). Si geothermobarometry of Y3 site estimates quartz equilibration at P=300 bars and T=360-380°C, coherent with Fe/Mn geothermometer (T=370±10°C). For Capelinhos, Fe/Mn suggests 398°C (±10°C) which is close to the critical point of seawater (P=300 bars and T=407°C). Other geothermobarometer uses Si/Cl vapor-like fluid to constrain depth of the top of reaction zone and predicts significant bias due to mixing along the up-flow zone. Application gives P=~370 bars, T=~435°C at Capelinhos and P=~390 bars, T=~440°C at Eiffel tower. This is further sustained by end-member 87Sr/86Sr=0.7038, which indicates little interaction of Capelinhos vent fluids with seawater-derived fluid, compared to other vapor-like sites with 87Sr/86Sr=0.7043. Because of its external location, Capelinhos site isn't influenced by the complex tectonic context of the

The Arctic Gakkel Vents (AGAVE) Expedition: Technology Development and the Search for Deep-Sea Hydrothermal Vent Fields Under the Arctic Ice Cap

NASA Astrophysics Data System (ADS)

Reves-Sohn, R. A.; Singh, H.; Humphris, S.; Shank, T.; Jakuba, M.; Kunz, C.; Murphy, C.; Willis, C.

2007-12-01

Deep-sea hydrothermal fields on the Gakkel Ridge beneath the Arctic ice cap provide perhaps the best terrestrial analogue for volcanically-hosted chemosynthetic biological communities that may exist beneath the ice-covered ocean of Europa. In both cases the key enabling technologies are robotic (untethered) vehicles that can swim freely under the ice and the supporting hardware and software. The development of robotic technology for deep- sea research beneath ice-covered oceans thus has relevance to both polar oceanography and future astrobiological missions to Europa. These considerations motivated a technology development effort under the auspices of NASA's ASTEP program and NSF's Office of Polar Programs that culminated in the AGAVE expedition aboard the icebreaker Oden from July 1 - August 10, 2007. The scientific objective was to study hydrothermal processes on the Gakkel Ridge, which is a key target for global studies of deep-sea vent fields. We developed two new autonomous underwater vehicles (AUVs) for the project, and deployed them to search for vent fields beneath the ice. We conducted eight AUV missions (four to completion) during the 40-day long expedition, which also included ship-based bathymetric surveys, CTD/rosette water column surveys, and wireline photographic and sampling surveys of remote sections of the Gakkel Ridge. The AUV missions, which lasted 16 hours on average and achieved operational depths of 4200 meters, returned sensor data that showed clear evidence of hydrothermal venting, but for a combination of technical reasons and time constraints, the AUVs did not ultimately return images of deep-sea vent fields. Nevertheless we used our wireline system to obtain images and samples of extensive microbial mats that covered fresh volcanic surfaces on a newly discovered set of volcanoes. The microbes appear to be living in regions where reducing and slightly warm fluids are seeping through cracks in the fresh volcanic terrain. These discoveries

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2014 CFR

2014-04-01

... drain piping for each toilet shall be vented by a 11/2 inch minimum diameter vent or rectangular vent of..., connected to the toilet drain by one of the following methods: (i) A 11/2 inch diameter (min.) individual vent pipe or equivalent directly connected to the toilet drain within the distance allowed in § 3280...

An analysis of flaring and venting activity in the Alberta upstream oil and gas industry.

PubMed

Johnson, Matthew R; Coderre, Adam R

2011-02-01

Alberta, Canada, is an important global producer of petroleum resources. In association with this production, large amounts of gas (1.14 billion m3 in 2008) are flared or vented. Although the amount of flaring and venting has been measurably reduced since 2002, data from 2005 reveal sharp increases in venting, which have important implications in terms of resource conservation and greenhouse gas emissions (which exceeded 8 million tonnes of carbon dioxide equivalent in 2008). With use of extensive monthly production data for 18,203 active batteries spanning the years 2002-2008 obtained in close cooperation with the Alberta Energy Resources Conservation Board, a detailed analysis has been completed to examine activity patterns of flaring and venting and reasons behind these trends in the Alberta upstream oil and gas industry. In any given year, approximately 6000 batteries reported flaring and/or venting, but the distribution of volumes flared and vented at individual sites was highly skewed, such that small numbers of sites handled large fractions of the total gas flaring and venting in the Province. Examination of month-to-month volume variability at individual sites, cast in terms of a nominal turndown ratio that would be required for a compressor to capture that gas and direct it into a pipeline, further revealed that volumes at a majority of sites were reasonably stable and there was no evidence that larger or more stable sites had been preferentially reduced, leaving potential barriers to future mitigation. Through linking of geospatial data with production data coupled with additional statistical analysis, the 31.2% increase in venting volumes since 2005 was revealed to be predominantly associated with increased production of heavier oils and bitumen in the Lloydminster region of the Province. Overall, the data suggest that quite significant reductions in flaring and venting could be realized by seeking mitigation solutions for only the largest batteries in

Heavy metals from Kueishantao shallow-sea hydrothermal vents, offshore northeast Taiwan

NASA Astrophysics Data System (ADS)

Chen, Xue-Gang; Lyu, Shuang-Shuang; Garbe-Schönberg, Dieter; Lebrato, Mario; Li, Xiaohu; Zhang, Hai-Yan; Zhang, Ping-Ping; Chen, Chen-Tung Arthur; Ye, Ying

2018-04-01

Shallow water hydrothermal vents are a source of heavy metals leading to their accumulation in marine organisms that manage to live under extreme environmental conditions. This is the case at Kueishantao (KST) shallow-sea vents system offshore northeast Taiwan, where the heavy metal distribution in vent fluids and ambient seawater is poorly understood. This shallow vent is an excellent natural laboratory to understand how heavy and volatile metals behave in the nearby water column and ecosystem. Here, we investigated the submarine venting of heavy metals from KST field and its impact on ambient surface seawater. The total heavy metal concentrations in the vent fluids and vertical plumes were 1-3 orders of magnitude higher than the overlying seawater values. When compared with deep-sea hydrothermal systems, the estimated KST end-member fluids exhibited much lower concentrations of transition metals (e.g., Fe and Mn) but comparable concentrations of toxic metals such as Pb and As. This may be attributed to the lower temperature of the KST reaction zone and transporting fluids. Most of the heavy metals (Fe, Mn, As, Y, and Ba) in the plumes and seawater mainly originated from hydrothermal venting, while Cd and Pb were largely contributed by external sources such as contaminated waters (anthropogenic origin). The spatial distribution of heavy metals in the surface seawater indicated that seafloor venting impacts ambient seawater. The measurable influence of KST hydrothermal activity, however, was quite localized and limited to an area of < 1 km2. The estimated annual fluxes of heavy metals emanating from the yellow KST hydrothermal vent were: 430-2600 kg Fe, 24-145 kg Mn, 5-32 kg Ba, 10-60 kg As, 0.3-1.9 kg Cd, and 2-10 kg Pb. This study provides important data on heavy metals from a shallow-sea hydrothermal field, and it helps to better understand the environmental impact of submarine shallow hydrothermal venting.

Characterizing the metatranscriptomic profile of archaeal metabolic genes at deep-sea hydrothermal vents in the Mid-Cayman Rise

NASA Astrophysics Data System (ADS)

Galambos, D.; Reveillaud, J. C.; Anderson, R.; Huber, J. A.

2017-12-01

Deep-sea hydrothermal vent systems host a wide diversity of bacteria, archaea and viruses. Although the geochemical conditions at these vents are well-documented, the relative metabolic activity of microbial lineages, especially among archaea, remains poorly characterized. The deep, slow-spreading Mid-Cayman Rise, which hosts the mafic-influenced Piccard and ultramafic-influenced Von Damm vent fields, allows for the comparison of vent sites with different geochemical characteristics. Previous metagenomic work indicated that despite the distinct geochemistry at Von Damm and Piccard, the functional profile of microbial communities between the two sites was similar. We examined relative metabolic gene activity using a metatranscriptomic analysis and observed functional similarity between Von Damm and Piccard, which is consistent with previous results. Notably, the relative expression of the methyl-coenzyme M reductase (mcr) gene was elevated in both vent fields. Additionally, we analyzed the ratio of RNA expression to DNA abundance of fifteen archaeal metagenome-assembled genomes (MAGs) across the two fields. Previous work showed higher archaeal diversity at Von Damm; our results indicate relatively even expression among archaeal lineages at Von Damm. In contrast, we observed lower archaeal diversity at Piccard, but individual archaeal lineages were very highly expressed; Thermoprotei showed elevated transcriptional activity, which is consistent with higher temperatures and sulfur levels at Piccard. At both Von Damm and Piccard, specific Methanococcus lineages were more highly expressed than others. Future analyses will more closely examine metabolic genes in these Methanococcus MAGs to determine why some lineages are more active at a vent field than others. We will conduct further statistical analyses to determine whether significant differences exist between Von Damm and Piccard and whether there are correlations between geochemical metadata and metabolic gene or

Soil temperature and CO2 degassing, SO2 fluxes and field observations before and after the February 29, 2016 new vent inside Nyiragongo crater

NASA Astrophysics Data System (ADS)

Balagizi, Charles M.; Yalire, Mathieu M.; Ciraba, Honoré M.; Kajeje, Vicky B.; Minani, Abel S.; Kinja, Annie B.; Kasereka, Marcellin M.

2016-09-01

Nyiragongo volcano threatens ˜1.5 million inhabitants of Goma (DR Congo) and Gisenyi (Rwanda) cities and people living in the surrounding villages. In 2002, the volcano produced lava flows which invaded Goma and destroyed the economic district of the city, forced a mass exodus of the population and caused the loss of several lives. Nyiragongo volcanic activity is therefore closely followed by the inhabitants, and any news related to increased activity agitates people in the area, especially those in Goma. Here, we report a short time series of soil temperature and carbon dioxide degassing for four locations, and plume sulphur dioxide fluxes preceding and following the opening of a new vent inside the main Nyiragongo crater on February 29, 2016. The observed sudden and unexpected changes in Nyiragongo activity raised the fear of a new volcanic eruption and led to panic in Goma and the surroundings, inducing some people to leaving the city. We use the dataset and field observations before and after the opening of the new vent, in conjunction with published information about Nyiragongo's eruptive mechanism and of the volcano's plumbing system geometry (mainly the crater), to show that the new vent was fed by magma intruded from the lava lake or the upper conduit.

Field Testing of an Unvented Roof with Fibrous Insulation, Tiles and Vapor Diffusion Venting

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

Ueno, K.; Lstiburek, J. W.

This research is a test implementation of an unvented tile roof assembly in a hot-humid climate (Orlando, FL; Zone 2A), insulated with air permeable insulation (netted and blown fiberglass). Given the localized moisture accumulation and failures seen in previous unvented roof field work, it was theorized that a 'diffusion vent' (water vapor open, but air barrier 'closed') at the highest points in the roof assembly might allow for the wintertime release of moisture, to safe levels. The 'diffusion vent' is an open slot at the ridge and hips, covered with a water-resistant but vapor open (500+ perm) air barrier membrane.more » As a control comparison, one portion of the roof was constructed as a typical unvented roof (self-adhered membrane at ridge). The data collected to date indicate that the diffusion vent roof shows greater moisture safety than the conventional, unvented roof design. The unvented roof had extended winter periods of 95-100% RH, and wafer (wood surrogate RH sensor) measurements indicating possible condensation; high moisture levels were concentrated at the roof ridge. In contrast, the diffusion vent roofs had drier conditions, with most peak MCs (sheathing) below 20%. In the spring, as outdoor temperatures warmed, all roofs dried well into the safe range (10% MC or less). Some roof-wall interfaces showed moderately high MCs; this might be due to moisture accumulation at the highest point in the lower attic, and/or shading of the roof by the adjacent second story. Monitoring will be continued at least through spring 2016 (another winter and spring).« less

Cyclic flank-vent and central-vent eruption patterns

NASA Astrophysics Data System (ADS)

Takada, Akira

Many basaltic and andesitic polygenetic volcanoes have cyclic eruptive activity that alternates between a phase dominated by flank eruptions and a phase dominated by eruptions from a central vent. This paper proposes the use of time-series diagrams of eruption sites on each polygenetic volcano and intrusion distances of dikes to evaluate volcano growth, to qualitatively reconstruct the stress history within the volcano, and to predict the next eruption site. In these diagrams the position of an eruption site is represented by the distance from the center of the volcano and the clockwise azimuth from north. Time-series diagrams of Mauna Loa, Kilauea, Kliuchevskoi, Etna, Sakurajima, Fuji, Izu-Oshima, and Hekla volcanoes indicate that fissure eruption sites of these volcanoes migrated toward the center of the volcano linearly, radially, or spirally with damped oscillation, occasionally forming a hierarchy in convergence-related features. At Krafla, terminations of dikes also migrated toward the center of the volcano with time. Eruption sites of Piton de la Fournaise did not converge but oscillated around the center. After the convergence of eruption sites with time, the central eruption phase is started. The intrusion sequence of dikes is modeled, applying crack interaction theory. Variation in convergence patterns is governed by the regional stress and the magma supply. Under the condition that a balance between regional extension and magma supply is maintained, the central vent convergence time during the flank eruption phase is 1-10 years, whereas the flank vent recurrence time during the central eruption phase is greater than 100 years owing to an inferred decrease in magma supply. Under the condition that magma supply prevails over regional extension, the central vent convergence time increases, whereas the flank vent recurrence time decreases owing to inferred stress relaxation. Earthquakes of M>=6 near a volcano during the flank eruption phase extend the

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 29.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Fuel System § 29.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 25.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant Fuel System § 25.975 Fuel tank vents and carburetor vapor vents. (a) Fuel tank vents. Each fuel tank must be vented from the... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents...

Microbial anaerobic methane cycling in the subseafloor at the Von Damm hydrothermal vent field, Mid-Cayman Rise

NASA Astrophysics Data System (ADS)

Huber, J. A.; Reveillaud, J. C.; Stepanauskas, R.; McDermott, J. M.; Sylva, S. P.; Seewald, J.

2013-12-01

The Mid-Cayman Rise (MCR) is Earth's deepest and slowest spreading mid-ocean ridge located in the western Caribbean. With an axial rift valley floor at a depth of ~4200-6500 m, it represents one of the deepest sections of ridge crest worldwide. In 2009, the world's deepest hydrothermal vents (Piccard at 4960 m) and an ultramafic-influenced system only 20 km away on top of an oceanic core complex (Von Damm at 2350 m) were discovered along the MCR. Each site is hosted in a distinct geologic setting with different thermal and chemical regimes. The Von Damm site is a particularly interesting location to examine chemolithoautotrophic subseafloor microbial communities due to the abundant hydrogen, methane, and organic compounds in the venting fluids. Here, we used a combination of stable isotope tracing, next-generation sequencing, and single cell techniques to determine the identity, activity, and genomic repertoire of subseafloor anaerobic archaea involved in methane cycling in hydrothermal fluids venting at the Von Damm site. Molecular sequencing of phylogenetic marker genes revealed the presence of diverse archaea that both generate and consume methane across a geochemical and thermal spectrum of vents. Stable isotope tracing experiments were used to detect biological utilization of formate and dissolved inorganic carbon, and methane generation at 70 °C under anaerobic conditions. Results indicate that methanogenesis with formate as a substrate is occurring at 70 °C at two Von Damm sites, Ginger Castle and the Main Orifice. The results are consistent with thermodynamic predictions for carbon speciation at the temperatures encountered at the ultramafic-hosted Von Damm, where formate is predicted to be thermodynamically stable, and may thus serve as a an important source of carbon. Diverse thermophilic methanogenic archaea belonging to the genera Methanothermococcus were detected at all vent sites with both 16S rRNA tag sequencing and single cell sorting. Other

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents and carburetor vapor vents...

14 CFR 23.975 - Fuel tank vents and carburetor vapor vents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Powerplant Fuel System § 23.975 Fuel tank vents and carburetor vapor vents. (a) Each fuel tank must be vented... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents and carburetor vapor vents...

Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge Hydrothermal Vents

DOE Data Explorer

Andrew Fowler

2015-10-01

Compilation of rare earth element and associated major and minor dissolved constituent analytical data for USA geothermal fields and global seafloor hydrothermal vents. Data is in original units. Reference to and use of this data should be attributed to the original authors and publications according to the provisions outlined therein.

Constrained circulation at Endeavour ridge facilitates colonization by vent larvae.

PubMed

Thomson, Richard E; Mihály, Steven F; Rabinovich, Alexander B; McDuff, Russell E; Veirs, Scott R; Stahr, Frederick R

2003-07-31

Understanding how larvae from extant hydrothermal vent fields colonize neighbouring regions of the mid-ocean ridge system remains a major challenge in oceanic research. Among the factors considered important in the recruitment of deep-sea larvae are metabolic lifespan, the connectivity of the seafloor topography, and the characteristics of the currents. Here we use current velocity measurements from Endeavour ridge to examine the role of topographically constrained circulation on larval transport along-ridge. We show that the dominant tidal and wind-generated currents in the region are strongly attenuated within the rift valley that splits the ridge crest, and that hydrothermal plumes rising from vent fields in the valley drive a steady near-bottom inflow within the valley. Extrapolation of these findings suggests that the suppression of oscillatory currents within rift valleys of mid-ocean ridges shields larvae from cross-axis dispersal into the inhospitable deep ocean. This effect, augmented by plume-driven circulation within rift valleys having active hydrothermal venting, helps retain larvae near their source. Larvae are then exported preferentially down-ridge during regional flow events that intermittently over-ride the currents within the valley.

New species of Ampharetidae (Annelida: Polychaeta) from the Arctic Loki Castle vent field

NASA Astrophysics Data System (ADS)

Kongsrud, Jon A.; Eilertsen, Mari H.; Alvestad, Tom; Kongshavn, Katrine; Rapp, Hans Tore

2017-03-01

Ampharetid polychaetes adapted to live in chemosynthetic environments are well known from the deep Pacific and Atlantic Oceans, but to date no such species have been reported from the Arctic Ocean. Here, we describe two new species, Paramytha schanderi gen. et sp. nov. and Pavelius smileyi sp. nov., from the Arctic Loki's Castle vent field on the Knipovich Ridge north-east of the island of Jan Mayen. The new species are both tube-builders, and are found in a sedimentary area at the NE flank of the vent field, characterized by low-temperature venting and barite chimneys. The new genus, Paramytha, is characterized by a prostomium without lobes or glandular ridges, smooth buccal tentacles, four pairs of cirriform branchiae arranged as 2+1+1 without median gap dorsally on segments II-IV, absence of chaetae (paleae) on segment II, and absence of modified segments. P. smileyi sp. nov. is placed in the previously monotypic genus Pavelius, primarily based on the presence of a rounded prostomium without lobes and four pairs of branchiae arranged in a single transverse row without median gap dorsally on segment III. Pavelius smileyi sp. nov. differs from the type species, Pavelius uschakovi, in the number of thoracic and abdominal chaetigers, and the absence of chaetae (paleae) on segment II. The phylogenetic position of the two new species from Loki's Castle is further explored by use of molecular data. New sequences of mitochondrial (16S rDNA and cytochrome c oxidase subunit 1, COI) and nuclear (18S rDNA) markers have been produced for both species from Loki's Castle, as well as for specimens identified as Paramytha sp. from Setùbal Canyon off Portugal, and for the following species: Pavelius uschakovi, Grassleia cf. hydrothermalis, Sosane wireni, Amphicteis ninonae and Samythella neglecta. Results from phylogenetic analysis, including 22 species and 12 genera of Ampharetidae, recovered Paramytha gen. nov. as monophyletic with maximum support, and a close relationship

Water column imaging on hydrothermal vent in Central Indian Ridge

NASA Astrophysics Data System (ADS)

Koh, J.; Park, Y.

2017-12-01

Water column imaging with Multibeam echosounder systems (MBES) is recently becoming of increasing interest for oceanographic studies. Especially gas bubbles and hot water exposed from hydrothermal vents make acoustic impedance anomalies in cold seawater, water column imaging is very useful for the researchers who want to detect some kinds of hydrothermal activity. We conducted a hydrothermal exploration program, called "INVENT17", using the MBES system, KONGBERG EM122 (12kHz, 1°×1°), mounted on R/V ISABU and we deployed other equipments including video guided hydraulic grab, tow-yo CTD and general CTD with MAPR (Miniature Autonomous Plume Recorder) in 2017. First, to evaluate its capabilities of detection of hydrothermal vent, the surveys using the MBES were conducted at the Solitaire Field, previously identified hydrothermal area of the Central Indian Ridge. The bathymetric data obtained from MBES provided information about detailed morphology of seafloor, but we were not able to achieve the information from the water column imaging data. But the clue of existence of active hydrothermal vent was detected through the values of ΔNTU, dEh/dt, and OPR gained from MAPR, the data means that the hydrothermal activity affects 100m from the seafloor. It could be the reason that we can't find the hydrothermal activity because the range resolution of water column imaging is pretty rough so that the size of 100m-scaled activity has low possibility to distinguish from seafloor. The other reason is there are no sufficient objects to cause strong scattering like as CO2 bubbles or droplets unlike in the mid-Okinawa Trough. And this suggests that can be a important standard to identify properties of hydrothermal vent sites depending on the presence of scattering objects in water mass. To justify this, we should perform more chemical analysis of hot water emanating from hydrothermal vent and collected several bottles of water sample to do that.

Gas venting system

DOEpatents

Khan, Amjad; Dreier, Ken Wayne; Moulthrop, Lawrence Clinton; White, Erik James

2010-06-29

A system to vent a moist gas stream is disclosed. The system includes an enclosure and an electrochemical cell disposed within the enclosure, the electrochemical cell productive of the moist gas stream. A first vent is in fluid communication with the electrochemical cell for venting the moist gas stream to an exterior of the enclosure, and a second vent is in fluid communication with an interior of the enclosure and in thermal communication with the first vent for discharging heated air to the exterior of the enclosure. At least a portion of the discharging heated air is for preventing freezing of the moist gas stream within the first vent.

Time-series analysis of fissure-fed multi-vent activity: a snapshot from the July 2014 eruption of Etna volcano (Italy)

NASA Astrophysics Data System (ADS)

Spina, L.; Taddeucci, J.; Cannata, A.; Sciotto, M.; Del Bello, E.; Scarlato, P.; Kueppers, U.; Andronico, D.; Privitera, E.; Ricci, T.; Pena-Fernandez, J.; Sesterhenn, J.; Dingwell, D. B.

2017-07-01

On 5 July 2014, an eruptive fissure opened on the eastern flank of Etna volcano (Italy) at 3.000 m a.s.l. Strombolian activity and lava effusion occurred simultaneously at two neighbouring vents. In the following weeks, eruptive activity led to the build-up of two cones, tens of meters high, here named Crater N and Crater S. To characterize the short-term (days) dynamics of this multi-vent system, we performed a multi-parametric investigation by means of a dense instrumental network. The experimental setup, deployed on July 15-16th at ca. 300 m from the eruption site, comprised two broadband seismometers and three microphones as well as high speed video and thermal cameras. Thermal analyses enabled us to characterize the style of eruptive activity at each vent. In particular, explosive activity at Crater N featured higher thermal amplitudes and a lower explosion frequency than at Crater S. Several episodes of switching between puffing and Strombolian activity were noted at Crater S through both visual observation and thermal data; oppositely, Crater N exhibited a quasi-periodic activity. The quantification of the eruptive style of each vent enabled us to infer the geometry of the eruptive system: a branched conduit, prone to rapid changes of gas flux accommodated at the most inclined conduit (i.e. Crater S). Accordingly, we were able to correctly interpret acoustic data and thereby extend the characterization of this two-vent system.

Investigating the Influence of Magmatic Volatile Input and Seawater Entrainment on Vent Deposit Morphology and Composition in Manus Basin (Back-arc) Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Tivey, M.; Bach, W.; Tivey, M.; Seewald, J.; Craddock, P.; Rouxel, O.; Yoerger, D.; Yeats, C.; McConachy, T.; Quigley, M.; Vanko, D.

2006-12-01

In August 2006, hydrothermal activity within the eastern Manus Basin north of Papua New Guinea was investigated using a combination of mapping (SeaBeam from the R/V Melville, near-bottom multi-beam sonar and magnetometer from AUV ABE and ROV Jason-2) and sampling (fluids and solids using ROV Jason-2). Objectives included identifying tectonic/geologic settings, examining interactions of seawater with felsic rocks that constitute the high silica end-member in the range of basement compositions, determining the extent of volatile magmatic inputs into these systems, and examining the evolution of hydrothermal activity through time. At the PACMANUS (Papua New Guinea Australia Canada Manus) area five previously discovered vent fields were mapped and sampled, and a new very active field, Fenway, was located south of the Satanic Mills field. The core of the Fenway field is a 40 m diameter two-tiered mound. A large black smoker complex venting boiling (356C, 172 bar) fluids forms the upper tier, with the lower tier composed of sulfide debris, massive anhydrite-sulfide deposits, and anhydrite sand. At the DESMOS Caldera hyaloclastites and extensive patches of bleached and stained substrate were mapped and sampled, as were diffuse (72C) and focused (119C) acidic fluids with a pH (25C) of 1.0; no sulfide deposits were observed in the area. At the North Su vent field within the SuSu Knolls area even lower pH fluids were sampled (see Seewald et al., this session). Hydrothermal activity includes venting of white sulfur-rich fluids through cracks and sediments, formation of native sulfur flanges, diffuse venting through spires, and black smoker activity (324C). Anhydrite cement is also present. The abundance of massive anhydrite at Fenway and presence of anhydrite cement at North Su is consistent with significant local entrainment and heating of seawater. The extremely low pH (less than 2) of some vent fluids supports previous hypotheses that fluids in this area contain

Advances in detection of diffuse seafloor venting using structured light imaging.

NASA Astrophysics Data System (ADS)

Smart, C.; Roman, C.; Carey, S.

2016-12-01

Systematic, remote detection and high resolution mapping of low temperature diffuse hydrothermal venting is inefficient and not currently tractable using traditional remotely operated vehicle (ROV) mounted sensors. Preliminary results for hydrothermal vent detection using a structured light laser sensor were presented in 2011 and published in 2013 (Smart) with continual advancements occurring in the interim. As the structured light laser passes over active venting, the projected laser line effectively blurs due to the associated turbulence and density anomalies in the vent fluid. The degree laser disturbance is captured by a camera collecting images of the laser line at 20 Hz. Advancements in the detection of the laser and fluid interaction have included extensive normalization of the collected laser data and the implementation of a support vector machine algorithm to develop a classification routine. The image data collected over a hydrothermal vent field is then labeled as seafloor, bacteria or a location of venting. The results can then be correlated with stereo images, bathymetry and backscatter data. This sensor is a component of an ROV mounted imaging suite which also includes stereo cameras and a multibeam sonar system. Originally developed for bathymetric mapping, the structured light laser sensor, and other imaging suite components, are capable of creating visual and bathymetric maps with centimeter level resolution. Surveys are completed in a standard mowing the lawn pattern completing a 30m x 30m survey with centimeter level resolution in under an hour. Resulting co-registered data includes, multibeam and structured light laser bathymetry and backscatter, stereo images and vent detection. This system allows for efficient exploration of areas with diffuse and small point source hydrothermal venting increasing the effectiveness of scientific sampling and observation. Recent vent detection results collected during the 2013-2015 E/V Nautilus seasons will be

Battery Vent Mechanism And Method

DOEpatents

Ching, Larry K. W.

2000-02-15

Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

Battery venting system and method

DOEpatents

Casale, Thomas J.; Ching, Larry K. W.; Baer, Jose T.; Swan, David H.

1999-01-05

Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve.

Geologic evolution of the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Denny, Alden R.; Kelley, Deborah S.; Früh-Green, Gretchen L.

2016-02-01

The Lost City Hydrothermal Field (LCHF) is a novel serpentinite-hosted vent field located on the Atlantis Massif southern wall. Results of 2 m resolution bathymetry, side scan, and video and still imagery, integrated with direct submersible observations provide the first high-resolution geologic map of the LCHF. These data form the foundation for an evolutionary model for the vent system over the past >120,000 years. The field is located on a down-dropped bench 70 m below the summit of the massif. The bench is capped by breccia and pelagic carbonate deposits underlain by variably deformed and altered serpentinite and gabbroic rocks. Hydrothermal activity is focused at the 60 m tall, 100 m across, massive carbonate edifice "Poseidon," which is venting 91°C fluid. Hydrothermal activity declines south and west of the Poseidon complex and dies off completely at distances greater than 200 m. East of Poseidon, the most recent stage of hydrothermal flow is characterized by egress of diffuse fluids from narrow fissures within a low-angle, anastomosing mylonite zone. South of the area of current hydrothermal activity, there is evidence of two discrete previously unrecognized relict fields. Active venting sites defined by carbonate-filled fissures that cut the carbonate cap rock at the summit of the massif mark the present-day northernmost extent of venting. These spatial relationships reflect multiple stages of field development, the northward migration of venting over time, and the likely development of a nascent field at the massif summit.

Variations in deep-sea hydrothermal vent communities on the Mid-Atlantic Ridge near the Azores plateau

NASA Astrophysics Data System (ADS)

Desbruyères, D.; Biscoito, M.; Caprais, J.-C.; Colaço, A.; Comtet, T.; Crassous, P.; Fouquet, Y.; Khripounoff, A.; Le Bris, N.; Olu, K.; Riso, R.; Sarradin, P.-M.; Segonzac, M.; Vangriesheim, A.

2001-05-01

Near the Azores Triple Junction as the Azores Plateau is approached, the ridge axis becomes shallower; its depth decreases from ca. 2400 m in the R AINBOW vent field (36°13'N) to ca. 850 m in the M ENEZ G WEN vent field (37°35'N). In this area, extensive mussel beds of the mytilid Bathymodiolus azoricus dominate the hydrothermal vent fauna, along with populations of three shrimps ( Rimicaris exoculata, Mirocaris fortunata and Chorocaris chacei). The main physical and chemical characteristics of the vent habitat were studied by discrete sampling, in situ analysis and sediment trap moorings. The vent fauna is distributed along a variable band where the vent fluids and seawater mix, with R. exoculata living in the most concentrated areas and Bathymodiolus azoricus in the most diluted zones. Various non-endemic species live at the border of the vent field. The variations observed in structure and composition of the communities along the depth gradient are most likely due to changes in vent fluid toxicity (metallic and sulphide content) and suspended mineral particles, which render the fluids harsher for species living there. The main faunal differences observed between L UCKY S TRIKE and M ENEZ G WEN hydrothermal fields are due to an impoverishment in the hydrothermal endemic species and to the penetration of bathyal species. The comparison of the three studied vent fields suggests the existence of a succession of several biogeographic islands rather than a single province.

Battery venting system and method

DOEpatents

Casale, T.J.; Ching, L.K.W.; Baer, J.T.; Swan, D.H.

1999-01-05

Disclosed herein is a venting mechanism for a battery. The venting mechanism includes a battery vent structure which is located on the battery cover and may be integrally formed therewith. The venting mechanism includes an opening extending through the battery cover such that the opening communicates with a plurality of battery cells located within the battery case. The venting mechanism also includes a vent manifold which attaches to the battery vent structure. The vent manifold includes a first opening which communicates with the battery vent structure opening and second and third openings which allow the vent manifold to be connected to two separate conduits. In this manner, a plurality of batteries may be interconnected for venting purposes, thus eliminating the need to provide separate vent lines for each battery. The vent manifold may be attached to the battery vent structure by a spin-welding technique. To facilitate this technique, the vent manifold may be provided with a flange portion which fits into a corresponding groove portion on the battery vent structure. The vent manifold includes an internal chamber which is large enough to completely house a conventional battery flame arrester and overpressure safety valve. In this manner, the vent manifold, when installed, lessens the likelihood of tampering with the flame arrester and safety valve. 8 figs.

Sources of organic carbon for Rimicaris hybisae: Tracing individual fatty acids at two hydrothermal vent fields in the Mid-Cayman rise

NASA Astrophysics Data System (ADS)

Streit, Kathrin; Bennett, Sarah A.; Van Dover, Cindy L.; Coleman, Max

2015-06-01

Hydrothermal vents harbor ecosystems mostly decoupled from organic carbon synthesized with the energy of sunlight (photosynthetic carbon source) but fueled instead by oxidation of reduced compounds to generate a chemosynthetic carbon source. Our study aimed to disentangle photosynthetic and chemosynthetic organic carbon sources for the shrimp species Rimicaris hybisae, a primary consumer presumed to obtain its organic carbon mainly from ectosymbiotic chemoautotrophic bacteria living on its gill cover membrane. To provide ectosymbionts with ideal conditions for chemosynthesis, these shrimp live in dense clusters around vent chimneys; they are, however, also found sparsely distributed adjacent to diffuse vent flows, where they might depend on alternative food sources. Densely and sparsely distributed shrimp were sampled and dissected into abdominal tissue and gill cover membrane, covered with ectosymbiotic bacteria, at two hydrothermal vent fields in the Mid-Cayman rise that differ in vent chemistry. Fatty acids (FA) were extracted from shrimp tissues and their carbon isotopic compositions assessed. The FA data indicate that adult R. hybisae predominantly rely on bacteria for their organic carbon needs. Their FA composition is dominated by common bacterial FA of the n7 family (~41%). Bacterial FA of the n4 FA family are also abundant and found to constitute good biomarkers for gill ectosymbionts. Sparsely distributed shrimp contain fractions of n4 FA in gill cover membranes ~4% lower than densely packed ones (~18%) and much higher fractions of photosynthetic FA in abdominal tissues, ~4% more (compared with 1.6%), suggesting replacement of ectosymbionts along with exoskeletons (molt), while they take up alternative diets of partly photosynthetic organic carbon. Abdominal tissues also contain photosynthetic FA from a second source taken up presumably during an early dispersal phase and still present to c. 3% in adult shrimp. The contribution of photosynthetic carbon to

Subseafloor Microbial Life in Venting Fluids from the Mid Cayman Rise Hydrothermal System

NASA Astrophysics Data System (ADS)

Huber, J. A.; Reveillaud, J.; Reddington, E.; McDermott, J. M.; Sylva, S. P.; Breier, J. A.; German, C. R.; Seewald, J.

2012-12-01

In hard rock seafloor environments, fluids emanating from hydrothermal vents are one of the best windows into the subseafloor and its resident microbial community. The functional consequences of an extensive population of microbes living in the subseafloor remains unknown, as does our understanding of how these organisms interact with one another and influence the biogeochemistry of the oceans. Here we report the abundance, activity, and diversity of microbes in venting fluids collected from two newly discovered deep-sea hydrothermal vents along the ultra-slow spreading Mid-Cayman Rise (MCR). Fluids for geochemical and microbial analysis were collected from the Von Damm and Piccard vent fields, which are located within 20 km of one another, yet have extremely different thermal, geological, and depth regimes. Geochemical data indicates that both fields are highly enriched in volatiles, in particular hydrogen and methane, important energy sources for and by-products of microbial metabolism. At both sites, total microbial cell counts in the fluids ranged in concentration from 5 x 10 4 to 3 x 10 5 cells ml-1 , with background seawater concentrations of 1-2 x 10 4 cells ml-1 . In addition, distinct cell morphologies and clusters of cells not visible in background seawater were seen, including large filaments and mineral particles colonized by microbial cells. These results indicate local enrichments of microbial communities in the venting fluids, distinct from background populations, and are consistent with previous enumerations of microbial cells in venting fluids. Stable isotope tracing experiments were used to detect utilization of acetate, formate, and dissolve inorganic carbon and generation of methane at 70 °C under anaerobic conditions. At Von Damm, a putatively ultra-mafic hosted site located at ~2200 m with a maximum temperature of 226 °C, stable isotope tracing experiments indicate methanogenesis is occurring in most fluid samples. No activity was detected

Fake ballistics and real explosions: field-scale experiments on the ejection and emplacement of volcanic bombs during vent-clearing explosive activity

NASA Astrophysics Data System (ADS)

Taddeucci, J.; Valentine, G.; Gaudin, D.; Graettinger, A. H.; Lube, G.; Kueppers, U.; Sonder, I.; White, J. D.; Ross, P.; Bowman, D. C.

2013-12-01

Ballistics - bomb-sized pyroclasts that travel from volcanic source to final emplacement position along ballistic trajectories - represent a prime source of volcanic hazard, but their emplacement range, size, and density is useful to inverse model key eruption parameters related to their initial ejection velocity. Models and theory, however, have so far focused on the trajectory of ballistics after leaving the vent, neglecting the complex dynamics of their initial acceleration phase in the vent/conduit. Here, we use field-scale buried explosion experiments to study the ground-to-ground ballistic emplacement of particles through their entire acceleration-deceleration cycle. Twelve blasts were performed at the University at Buffalo Large Scale Experimental Facility with a range of scaled depths (burial depth divided by the cubic root of the energy of the explosive charge) and crater configurations. In all runs, ballistic analogs were placed on the ground surface at variable distance from the vertical projection of the buried charge, resulting in variable ejection angle. The chosen analogs are tennis and ping-pong balls filled with different materials, covering a limited range of sizes and densities. The analogs are tracked in multiple high-speed and high-definition videos, while Particle Image Velocimetry is used to detail ground motion in response to the buried blasts. In addition, after each blast the emplacement position of all analog ballistics was mapped with respect to the blast location. Preliminary results show the acceleration history of ballistics to be quite variable, from very short and relatively simple acceleration coupled with ground motion, to more complex, multi-stage accelerations possibly affected not only by the initial ground motion but also by variable coupling with the gas-particle mixture generated by the blasts. Further analysis of the experimental results is expected to provide new interpretative tools for ballistic deposits and better

The vent microbiome: patterns and drivers

NASA Astrophysics Data System (ADS)

Pachiadaki, M.

2015-12-01

Microbial processes within deep-sea hydrothermal vents affect the global biogeochemical cycles. Still, there are significant gaps in our understanding of the microbiology and the biogeochemistry of deep-sea hydrothermal systems. Vents differ in temperature, host rock composition and fluid chemistry; factors that are hypothesized to shape the distribution of the microbial communities, their metabolic capabilities and their activities. Using large-scale single cell genomics, we obtained insights into the genomic content of several linkages of a diffuse flow vent. The genomes show high metabolic versatility. Sulfur oxidation appears to be predominant but there is the potential of using a variety of e- donors and acceptors to obtain energy. To further assess the ecological importance of the vent auto- and heterotrophs, the global biogeography of the analyzed lineages will be investigated by fragment recruitment of metagenomes produced from the same site as well as other hydrothermal systems. Metatranscriptomic and metaproteomic data will be integrated to examine the expression of the predominant metabolic pathways and thus the main energy sources driving chemoautotrophic production. The comparative analysis of the key players and associated pathways among various vent sites that differ in physicochemical characteristics is anticipated to decipher the patterns and drivers of the global dispersion and the local diversification of the vent microbiome.

Analysis of sound absorption performance of an electroacoustic absorber using a vented enclosure

NASA Astrophysics Data System (ADS)

Cho, Youngeun; Wang, Semyung; Hyun, Jaeyub; Oh, Seungjae; Goo, Seongyeol

2018-03-01

The sound absorption performance of an electroacoustic absorber (EA) is primarily influenced by the dynamic characteristics of the loudspeaker that acts as the actuator of the EA system. Therefore, the sound absorption performance of the EA is maximum at the resonance frequency of the loudspeaker and tends to degrade in the low-frequency and high-frequency bands based on this resonance frequency. In this study, to adjust the sound absorption performance of the EA system in the low-frequency band of approximately 20-80 Hz, an EA system using a vented enclosure that has previously been used to enhance the radiating sound pressure of a loudspeaker in the low-frequency band, is proposed. To verify the usefulness of the proposed system, two acoustic environments are considered. In the first acoustic environment, the vent of the vented enclosure is connected to an external sound field that is distinct from the sound field coupled to the EA. In this case, the acoustic effect of the vented enclosure on the performance of the EA is analyzed through an analytical approach using dynamic equations and an impedance-based equivalent circuit. Then, it is verified through numerical and experimental approaches. Next, in the second acoustic environment, the vent is connected to the same external sound field as the EA. In this case, the effect of the vented enclosure on the EA is investigated through an analytical approach and finally verified through a numerical approach. As a result, it is confirmed that the characteristics of the sound absorption performances of the proposed EA system using the vented enclosure in the two acoustic environments considered in this study are different from each other in the low-frequency band of approximately 20-80 Hz. Furthermore, several case studies on the change tendency of the performance of the EA using the vented enclosure according to the critical design factors or vent number for the vented enclosure are also investigated. In the future

Ecology and biogeography of megafauna and macrofauna at the first known deep-sea hydrothermal vents on the ultraslow-spreading Southwest Indian Ridge

PubMed Central

Copley, J. T.; Marsh, L.; Glover, A. G.; Hühnerbach, V.; Nye, V. E.; Reid, W. D. K.; Sweeting, C. J.; Wigham, B. D.; Wiklund, H.

2016-01-01

The Southwest Indian Ridge is the longest section of very slow to ultraslow-spreading seafloor in the global mid-ocean ridge system, but the biogeography and ecology of its hydrothermal vent fauna are previously unknown. We collected 21 macro- and megafaunal taxa during the first Remotely Operated Vehicle dives to the Longqi vent field at 37° 47′S 49° 39′E, depth 2800 m. Six species are not yet known from other vents, while six other species are known from the Central Indian Ridge, and morphological and molecular analyses show that two further polychaete species are shared with vents beyond the Indian Ocean. Multivariate analysis of vent fauna across three oceans places Longqi in an Indian Ocean province of vent biogeography. Faunal zonation with increasing distance from vents is dominated by the gastropods Chrysomallon squamiferum and Gigantopelta aegis, mussel Bathymodiolus marisindicus, and Neolepas sp. stalked barnacle. Other taxa occur at lower abundance, in some cases contrasting with abundances at other vent fields, and δ13C and δ15N isotope values of species analysed from Longqi are similar to those of shared or related species elsewhere. This study provides baseline ecological observations prior to mineral exploration activities licensed at Longqi by the United Nations. PMID:27966649

Venting test analysis using Jacob`s approximation

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

Edwards, K.B.

1996-03-01

There are many sites contaminated by volatile organic compounds (VOCs) in the US and worldwide. Several technologies are available for remediation of these sites, including excavation, pump and treat, biological treatment, air sparging, steam injection, bioventing, and soil vapor extraction (SVE). SVE is also known as soil venting or vacuum extraction. Field venting tests were conducted in alluvial sands residing between the water table and a clay layer. Flow rate, barometric pressure, and well-pressure data were recorded using pressure transmitters and a personal computer. Data were logged as frequently as every second during periods of rapid change in pressure. Testsmore » were conducted at various extraction rates. The data from several tests were analyzed concurrently by normalizing the well pressures with respect to extraction rate. The normalized pressures vary logarithmically with time and fall on one line allowing a single match of the Jacob approximation to all tests. Though the Jacob approximation was originally developed for hydraulic pump test analysis, it is now commonly used for venting test analysis. Only recently, however, has it been used to analyze several transient tests simultaneously. For the field venting tests conducted in the alluvial sands, the air permeability and effective porosity determined from the concurrent analysis are 8.2 {times} 10{sup {minus}7} cm{sup 2} and 20%, respectively.« less

Vented Chill / No-Vent Fill of Cryogenic Propellant Tanks

NASA Technical Reports Server (NTRS)

Rhys, Noah O.; Foster, Lee W.; Martin, Adam K.; Stephens, Jonathan R.

2016-01-01

Architectures for extended duration missions often include an on-orbit replenishment of the space vehicle's cryogenic liquid propellants. Such a replenishment could be accomplished via a tank-to-tank transfer from a dedicated tanker or a more permanent propellant depot storage tank. Minimizing the propellant loss associated with transfer line and receiver propellant tank thermal conditioning is essential for mass savings. A new methodology for conducting tank-to-tank transfer while minimizing such losses has been demonstrated. Charge-Hold-Vent is the traditional methodology for conducting a tank-to-tank propellant transfer. A small amount of cryogenic liquid is introduced to chill the transfer line and propellant tank. As the propellant absorbs heat and undergoes a phase change, the tank internal pressure increases. The tank is then vented to relieve pressure prior to another charge of cryogenic liquid being introduced. This cycle is repeated until the transfer lines and tank are sufficiently chilled and the replenishment of the propellant tank is complete. This method suffers inefficiencies due to multiple chill and vent cycles within the transfer lines and associated feed system components. Additionally, this system requires precise measuring of cryogenic fluid delivery for each transfer, multiple valve cycling events, and other complexities associated with cycled operations. To minimize propellant loss and greatly simplify on-orbit operations, an alternate methodology has been designed and demonstrated. The Vented Chill / No Vent Fill method is a simpler, constant flow approach in which the propellant tank and transfer lines are only chilled once. The receiver tank is continuously vented as cryogenic liquid chills the transfer lines, tank mass and ullage space. Once chilled sufficiently, the receiver tank valve is closed and the tank is completely filled. Interestingly, the vent valve can be closed prior to receiver tank components reaching liquid saturation

Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: geochemical controls on microbial community structure and function

PubMed Central

Inskeep, William P.; Jay, Zackary J.; Macur, Richard E.; Clingenpeel, Scott; Tenney, Aaron; Lovalvo, David; Beam, Jacob P.; Kozubal, Mark A.; Shanks, W. C.; Morgan, Lisa A.; Kan, Jinjun; Gorby, Yuri; Yooseph, Shibu; Nealson, Kenneth

2015-01-01

Yellowstone Lake (Yellowstone National Park, WY, USA) is a large high-altitude (2200 m), fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007–2008) using a remotely operated vehicle (ROV). Sublacustrine thermal vent waters (circa 50–90°C) contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous “streamer” communities of Inflated Plain and West Thumb (pH range 5–6) were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot's Crater (pH 5–6). Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S), hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP. PMID:26579074

Continental shelf and slope gas venting off Cascadia

NASA Astrophysics Data System (ADS)

Scherwath, Martin; Riedel, Michael; Roemer, Miriam; Juniper, Kim; Heesemann, Martin; Mihaly, Steven; Paull, Charles; Spence, George; Veloso, Mario

2017-04-01

Along the Cascadia Margin in the Northeast Pacific, off the coasts of British Columbia, Washington and Oregon, hundreds natural gas vent locations have been mapped using sonar data from ships, autonomous underwater and also remotely operated vehicles, as well as camera and seafloor sonar data. We have combined observed vent locations from published literature as well as analyzed original data from research cruises and fishing sonar from various archives, including those of Natural Resources Canada, the Monterey Bay Aquarium Research Institute, Ocean Networks Canada, the National Ocean and Atmospheric Administration, and the Schmidt Ocean Institute. In total, over 950 individual vents are now mapped. By far the highest accumulation of gas vent locations appear both shallow (<250 m) and concentrated towards the mouth of the Juan de Fuca Strait, however these observations are naturally biased toward the distribution of the observation footprints. Normalized observations confirm the shallow (<500 m) high concentrations of gas vents but also establish some deeper sections of focused venting activity. We will speculate about the reasons behind the distribution, focus on specific examples, extrapolate for rough margin flux rate ranges and comment on short-comings and future directions for margin-wide gas vent studies.

Microbial Community Structure of Deep-sea Hydrothermal Vents on the Ultraslow Spreading Southwest Indian Ridge

PubMed Central

Ding, Jian; Zhang, Yu; Wang, Han; Jian, Huahua; Leng, Hao; Xiao, Xiang

2017-01-01

Southwest Indian Ridge (SWIR) is a typical oceanic ultraslow spreading ridge with intensive hydrothermal activities. The microbial communities in hydrothermal fields including primary producers to support the entire ecosystem by utilizing geochemical energy generated from rock-seawater interactions. Here we have examined the microbial community structures on four hydrothermal vents from SWIR, representing distinct characteristics in terms of temperature, pH and metal compositions, by using Illumina sequencing of the 16S small subunit ribosomal RNA (rRNA) genes, to correlate bacterial and archaeal populations with the nature of the vents influenced by ultraslow spreading features. Epsilon-, Gamma-, Alpha-, and Deltaproteobacteria and members of the phylum Bacteroidetes and Planctomycetes, as well as Thaumarchaeota, Woesearchaeota, and Euryarchaeota were dominant in all the samples. Both bacterial and archaeal community structures showed distinguished patterns compared to those in the fast-spreading East Pacific Ridge or the slow-spreading Mid-Atlantic Ridge as previously reported. Furthermore, within SWIR, the microbial communities are highly correlated with the local temperatures. For example, the sulfur-oxidizing bacteria were dominant within bacteria from low-temperature vents, but were not represented as the dominating group recovered from high temperature (over 300°C) venting chimneys in SWIR. Meanwhile, Thaumarchaeota, the ammonium oxidizing archaea, only showed high relative abundance of amplicons in the vents with high-temperature in SWIR. These findings provide insights on the microbial community in ultraslow spreading hydrothermal fields, and therefore assist us in the understanding of geochemical cycling therein. PMID:28659873

Food-web complexity across hydrothermal vents on the Azores triple junction

NASA Astrophysics Data System (ADS)

Portail, Marie; Brandily, Christophe; Cathalot, Cécile; Colaço, Ana; Gélinas, Yves; Husson, Bérengère; Sarradin, Pierre-Marie; Sarrazin, Jozée

2018-01-01

The assessment and comparison of food webs across various hydrothermal vent sites can enhance our understanding of ecological processes involved in the structure and function of biodiversity. The Menez Gwen, Lucky Strike and Rainbow vent fields are located on the Azores triple junction of the Mid-Atlantic Ridge. These fields have distinct depths (from 850 to 2320 m) and geological contexts (basaltic and ultramafic), but share similar faunal assemblages defined by the presence of foundation species that include Bathymodiolus azoricus, alvinocarid shrimp and gastropods. We compared the food webs of 13 faunal assemblages at these three sites using carbon and nitrogen stable isotope analyses (SIA). Results showed that photosynthesis-derived organic matter is a negligible basal source for vent food webs, at all depths. The contribution of methanotrophy versus autotrophy based on Calvin-Benson-Bassham (CBB) or reductive tricarboxylic acid (rTCA) cycles varied between and within vent fields according to the concentrations of reduced compounds (e.g. CH4, H2S). Species that were common to vent fields showed high trophic flexibility, suggesting weak trophic links to the metabolism of chemosynthetic primary producers. At the community level, a comparison of SIA-derived metrics between mussel assemblages from two vent fields (Menez Gwen & Lucky Strike) showed that the functional structure of food webs was highly similar in terms of basal niche diversification, functional specialization and redundancy. Coupling SIA to functional trait approaches included more variability within the analyses, but the functional structures were still highly comparable. These results suggest that despite variable environmental conditions (physico-chemical factors and basal sources) and faunal community structure, functional complexity remained relatively constant among mussel assemblages. This functional similarity may be favoured by the propensity of species to adapt to fluid variations and

Structure of hydrothermal plumes at the Logatchev vent field, 14°45‧N, Mid-Atlantic Ridge: evidence from geochemical and geophysical data

NASA Astrophysics Data System (ADS)

Sudarikov, S. M.; Roumiantsev, A. B.

2000-09-01

In the Seventh cruise of R/V ;Professor Logatchev; anomalies of natural electric field (EF), Eh and pS were discovered using a towed instrument package (RIFT) at 14°45‧N on the MAR (Logatchev hydrothermal field). The anomalous zone (AZ) is situated close (10-35 m) to two low-temperature venting areas of degrading sulphides and a black smoker (Irina-Microsmoke) forming a distinct buoyant plume. Over or close to the main area of high-temperature venting situated to the south-east from the AZ, no EF or Eh anomalies were observed. According to the results of Mir dives the highly mineralised solutions from smoking craters at the main mound mostly form non-buoyant plumes (reverse-plumes). The buoyant plume structure shows the differentiation of the electrical and Eh fields within the plume. Maxima of the EF, Eh and EH2S anomalies were revealed in the lower part (∼15 m) of the plume. The negative redox potential plume coupled with a sulphide anomaly is more localized in comparison with the EF. This observation indicates a distinct change in the composition of buoyant plume water, which may be due to the formation and fallout of early formed Fe sulphide particles soon after venting.

Abundant Hydrothermal Venting in the Southern Ocean Near 62°S/159°E on the Australian-Antarctic Ridge

NASA Astrophysics Data System (ADS)

Baker, E. T.; Hahm, D.; Rhee, T. S.; Park, S. H.; Lupton, J. E.; Walker, S. L.; Choi, H.

2014-12-01

Circum-Antarctic Ridges (CARs) comprise almost one-third of the global Mid-Ocean Ridge, yet remain terra incognita for hydrothermal activity and chemosynthetic ecosystems. The InterRidge Vents Database lists only 3 confirmed (visualized) and 35 inferred (plume evidence) active sites along the ~21,000 km of CARs. Here, we report on a multi-year effort to locate and characterize hydrothermal activity on two 1st-order segments of the Australian-Antarctic Ridge that are perhaps more isolated from other known vent fields than any other vent site on the Mid-Ocean Ridge. KR1 is a 300-km-long segment near 62°S/159°E, and KR2 a 90-km-long segment near 60°S/152.5°E. We used profiles collected by Miniature Autonomous Plume Recorders (MAPRs) on rock corers in March and December of 2011 to survey each segment, and an intensive CTD survey in Jan/Feb 2013 to pinpoint sites and sample plumes on KR1. Optical and oxidation-reduction potential (ORP, aka Eh) anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ~25 km. Forty profiles on KR1 identified 13 sites, some within a few km of each other. The densest site concentration on KR1 occurred along a relatively inflated, 90-km-long section near the segment center. CTD tows covered 20 km of the eastern, most inflated portion of this area, finding two 6-km-long zones centered near 158.6°E and 158.8°E with multiple plume anomalies. Three ORP anomalies within 50 m of the seafloor indicate precise venting locations. We call this area the Mujin "Misty Harbor" vent field. Vent frequency sharply decreases away from Mujin. 3He/heat ratios determined from 20 plume samples in the Mujin field were mostly <0.015 fM/J, indicative of chronic venting, but 3 samples, 0.021-0.034 fM/J, are ratios typical of a recent eruption. The spatial density of hydrothermal activity along KR1 and KR2 is similar to other intermediate-rate spreading ridges. We calculate the plume incidence (ph) along

Natural Gas Venting on the Northern Cascadia Margin

NASA Astrophysics Data System (ADS)

Scherwath, M.; Riedel, M.; Roemer, M.; Paull, C. K.; Spence, G.; Veloso, M.

2016-12-01

Over the past decades, hundreds of natural gas vents have been observed along the Northern Cascadia Margin in the Northeast Pacific, and we present a summary of these observations from offshore Vancouver Island, BC, Canada. We have gathered observed locations and analyzed original data from published literature as well as research cruises and fishing sonar from various archives. By far the highest accumulation of gas vent locations appear both shallow (100-200 m) and concentrated towards the mouth of the Juan de Fuca Strait, however these observations are naturally biased toward the distribution of the observation footprints. Normalized observations confirm the shallow high concentrations of gas vents but also establish some deeper sections of focused venting activity. We will speculate about the reasons behind the distribution, focus on specific examples, extrapolate for rough margin flux rate ranges and comment on short-comings and future directions for margin-wide gas vent studies.

Investigations of a novel fauna from hydrothermal vents along the Arctic Mid-Ocean Ridge (AMOR) (Invited)

NASA Astrophysics Data System (ADS)

Rapp, H.; Schander, C.; Halanych, K. M.; Levin, L. A.; Sweetman, A.; Tverberg, J.; Hoem, S.; Steen, I.; Thorseth, I. H.; Pedersen, R.

2010-12-01

The Arctic deep ocean hosts a variety of habitats ranging from fairly uniform sedimentary abyssal plains to highly variable hard bottoms on mid ocean ridges, including biodiversity hotspots like seamounts and hydrothermal vents. Deep-sea hydrothermal vents are usually associated with a highly specialized fauna, and since their discovery in 1977 more than 400 species of animals have been described. This fauna includes various animal groups of which the most conspicuous and well known are annelids, mollusks and crustaceans. The newly discovered deep sea hydrothermal vents on the Mohns-Knipovich ridge north of Iceland harbour unique biodiversity. The Jan Mayen field consists of two main areas with high-temperature white smoker venting and wide areas with low-temperature seepage, located at 5-700 m, while the deeper Loki Castle vent field at 2400 m depth consists of a large area with high temperature black smokers surrounded by a sedimentary area with more diffuse low-temperature venting and barite chimneys. The Jan Mayen sites show low abundance of specialized hydrothermal vent fauna. Single groups have a few specialized representatives but groups otherwise common in hydrothermal vent areas are absent. Slightly more than 200 macrofaunal species have been identified from this vent area, comprising mainly an assortment of bathyal species known from the surrounding area. Analysis of stable isotope data also indicates that the majority of the species present are feeding on phytodetritus and/or phytoplankton. However, the deeper Loki Castle vent field contains a much more diverse vent endemic fauna with high abundances of specialized polychaetes, gastropods and amphipods. These specializations also include symbioses with a range of chemosynthetic microorganisms. Our data show that the fauna composition is a result of high degree of local specialization with some similarities to the fauna of cold seeps along the Norwegian margin and wood-falls in the abyssal Norwegian Sea

Gas hydrate and spatial venting variations in the continental margin offshore Southwestern Taiwan

NASA Astrophysics Data System (ADS)

Lin, S.; Lim, Y.; Hsieh, W.; Yang, T.; Wang, Y.

2006-12-01

Strong BSR, high methane contents and rapid sulfate reduction were found in the continental margin sediments offshore southwestern Taiwan. In order to identify the venting phenomena and its relationship with gas hydrate, this research investigate sea floor vent features using WHOI?|s Towcam system as well as piston core in the study region. A total of 10 dives were conducted on board the r/v OR-1. Pore water sulfate, dissolved sulfide, methane, chloride, del O18 ratio, sediment organic carbon, carbonate content and carbonate del C13 ratio, pyrite-S were measured Large spatial variations were found based on pictures obtained from Towcam system and piston cores. Active venting features include bacteria mat, live dense bivalve patches, gas plume, temperature and salinity fluctuations, rapid sulfate reduction and high concentrations of methane in sediments. In addition, vent chimney, pockmark and large authigenic carbonate buildup were also observed in the active venting area. In contrast, in some areas without active venting features, scatter dead chimney, semi- buried carbonate structures, and dead bivalves were found. Total sulfate depletion was found at depth as shallow as 1 meter below sediment water interface in area near active vent whereas almost no sulfate depletion was observed in areas without any vent feature. Stages of carbonate build up existed, with initial phase dominated by small tube, chimney, and later with massive carbonate structures protruding the sea floor. The appearances of massive carbonate buildup structures seemed to indicate the end stage of gas hydrate venting phenomena.

Testing of an Ammonia EVA Vent Tool for the International Space Station

NASA Technical Reports Server (NTRS)

Ungar, Eugene K.; Stanewich, Brett J.; Wilhelm, Sheri Munekata

2000-01-01

When components of the International Space Station ammonia External Active Thermal Control System are replaced on-orbit, they must be vented immediately after removal from the system. Venting ensures that the component is not hard packed with liquid and thus does not pose a hazard. An extravehicular activity (EVA) vent tool has been developed to perform this function. However, there were concerns that the tool could whip, posing a hazard to the EVA astronaut, or would freeze. The ammonia vent tool was recently tested in a thermal/vacuum chamber to demonstrate that it would operate safely and would not freeze during venting. During the test, ammonia mimicking the venting conditions for six different heat exchanger initial conditions was passed through representative test articles. In the present work, the model that was used to develop the ammonia state and flow for the test points is discussed and the test setup and operation is described. The qualitative whipping and freezing results of the test are discussed and vent plume pressure measurements are described and interpreted.

Coupled fluid and solid evolution in analogue volcanic vents

NASA Astrophysics Data System (ADS)

Solovitz, Stephen A.; Ogden, Darcy E.; Kim, Dave (Dae-Wook); Kim, Sang Young

2014-07-01

Volcanic eruptions emit rock particulates and gases at high speed and pressure, which change the shape of the surrounding rock. Simplified analytical solutions, field studies, and numerical models suggest that this process plays an important role in the behavior and hazards associated with explosive volcanic eruptions. Here we present results from a newly developed laboratory-scale apparatus designed to study this coupled process. The experiments used compressed air jets expanding into the laboratory through fabricated rock analogue material, which evolves through time during the experiment. The compressed air was injected at approximately 2.5 times atmospheric pressure. We fabricated rock analogues from sand and steel powder samples with a three-dimensional printing process. We studied the fluid development using phase-locked particle image velocimetry, while simultaneously observing the solid development via a video camera. We found that the fluid response was much more rapid than that of the solid, permitting a quasi-steady approximation. In most cases, the solid vent flared out rapidly, increasing its diameter by 20 to 100%. After the initial expansion, the vent and flow field achieved a near-steady condition for a long duration. The new expanded vent shapes permitted lower vent exit pressures and larger jet radii. In one experiment, after an initial vent shape development and establishment of steady flow behavior, rock failure occurred a second time, resulting in a new exit diameter and new steady state. This second failure was not precipitated by changes in the nozzle flow condition, and it radically changed the downstream flow dynamics. This experiment suggests that the brittle nature of volcanic host rock enables sudden vent expansion in the middle of an eruption without requiring a change in the conduit flow.

Hyper Vent-ilating

NASA Image and Video Library

2015-04-13

This series of oblique images highlight the wall and exterior of the beautiful volcanic vent located to the northeast of Rachmaninoff basin and west of Copland crater. Layering can be seen along a portion of the wall and the exterior is smooth due to a blanket of fine particles of lava that were ejected explosively from the vent in a pyroclastic eruption. This vent is deeper than Earth's Grand Canyon. http://photojournal.jpl.nasa.gov/catalog/PIA19282

Distribution and relative importance of jellyfish in a region of hydrothermal venting

NASA Astrophysics Data System (ADS)

Burd, Brenda J.; Thomson, Richard E.

2000-09-01

Net sampling to 3000 m depth at Endeavour Ridge in the northeast Pacific in July 1991-1994 shows that medusae in the immediate vicinity of the hydrothermal vent fields often make up a larger proportion of the total zooplankton abundance and biomass from mesopelagic to bathypelagic depths than in the surrounding waters. This was particularly evident in the dominant Trachymedusae, and least evident in the siphonophores. In addition, the large red Scyphomedusa Stygiomedusa gigantea was a major biomass component in the region of the deep (1000-1800 m depth) migrating scattering layers at the vent field, but was not found in any net tows greater than 10 km away from vents. There is no concurrent increase in relative or percent biomass of fish or chaetognaths, which are the other major predators in the community. We hypothesize that predaceous medusae respond opportunistically to the enhanced zooplankton biomass throughout the water column around vents in spring to early summer, in a way that other predators do not.

Airbag vent valve and system

NASA Technical Reports Server (NTRS)

Peterson, Leslie D. (Inventor); Zimmermann, Richard E. (Inventor)

2001-01-01

An energy absorbing airbag system includes one or more vent valve assemblies for controlling the release of airbag inflation gases to maintain inflation gas pressure within an airbag at a substantially constant pressure during a ride-down of an energy absorbing event. Each vent valve assembly includes a cantilever spring that is flat in an unstressed condition and that has a free end portion. The cantilever spring is secured to an exterior surface of the airbag housing and flexed to cause the second free end portion of the cantilever spring to be pressed, with a preset force, against a vent port or a closure covering the vent port to seal the vent port until inflation gas pressure within the airbag reaches a preselected value determined by the preset force whereupon the free end portion of the cantilever spring is lifted from the vent port by the inflation gases within the airbag to vent the inflation gases from within the airbag. The resilience of the cantilever spring maintains a substantially constant pressure within the airbag during a ride-down portion of an energy absorbing event by causing the cantilever spring to vent gases through the vent port whenever the pressure of the inflation gases reaches the preselected value and by causing the cantilever spring to close the vent port whenever the pressure of the inflation gases falls below the preselected value.

Diversity and function in microbial mats from the Lucky Strike hydrothermal vent field.

PubMed

Crépeau, Valentin; Cambon Bonavita, Marie-Anne; Lesongeur, Françoise; Randrianalivelo, Henintsoa; Sarradin, Pierre-Marie; Sarrazin, Jozée; Godfroy, Anne

2011-06-01

Diversity and function in microbial mats from the Lucky Strike hydrothermal vent field (Mid-Atlantic Ridge) were investigated using molecular approaches. DNA and RNA were extracted from mat samples overlaying hydrothermal deposits and Bathymodiolus azoricus mussel assemblages. We constructed and analyzed libraries of 16S rRNA gene sequences and sequences of functional genes involved in autotrophic carbon fixation [forms I and II RuBisCO (cbbL/M), ATP-citrate lyase B (aclB)]; methane oxidation [particulate methane monooxygenase (pmoA)] and sulfur oxidation [adenosine-5'-phosphosulfate reductase (aprA) and soxB]. To gain new insights into the relationships between mats and mussels, we also used new domain-specific 16S rRNA gene primers targeting Bathymodiolus sp. symbionts. All identified archaeal sequences were affiliated with a single group: the marine group 1 Thaumarchaeota. In contrast, analyses of bacterial sequences revealed much higher diversity, although two phyla Proteobacteria and Bacteroidetes were largely dominant. The 16S rRNA gene sequence library revealed that species affiliated to Beggiatoa Gammaproteobacteria were the dominant active population. Analyses of DNA and RNA functional gene libraries revealed a diverse and active chemolithoautotrophic population. Most of these sequences were affiliated with Gammaproteobacteria, including hydrothermal fauna symbionts, Thiotrichales and Methylococcales. PCR and reverse transcription-PCR using 16S rRNA gene primers targeted to Bathymodiolus sp. symbionts revealed sequences affiliated with both methanotrophic and thiotrophic endosymbionts. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Hunting for Hydrothermal Vents at the Local-Scale Using AUV's and Machine-Learning Classification in the Earth's Oceans

NASA Astrophysics Data System (ADS)

White, S. M.

2018-05-01

New AUV-based mapping technology coupled with machine-learning methods for detecting individual vents and vent fields at the local-scale raise the possibility of understanding the geologic controls on hydrothermal venting.

Arsenic bioaccumulation and biotransformation in deep-sea hydrothermal vent organisms from the PACMANUS hydrothermal field, Manus Basin, PNG

NASA Astrophysics Data System (ADS)

Price, Roy E.; Breuer, Christian; Reeves, Eoghan; Bach, Wolfgang; Pichler, Thomas

2016-11-01

Hydrothermal vents are often enriched in arsenic, and organisms living in these environments may accumulate high concentrations of this and other trace elements. However, very little research to date has focused on understanding arsenic bioaccumulation and biotransformation in marine organisms at deep-sea vent areas; none to date have focused organisms from back-arc spreading centers. We present for the first time concentration and speciation data for As in vent biota from several hydrothermal vent fields in the eastern Manus basin, a back-arc basin vent field located in the Bismark Sea, western Pacific Ocean. The gastropods Alviniconcha hessleri and Ifremeria nautilei, and the mussel Bathymodiolus manusensis were collected from diffuse venting areas where pH was slightly lower (6.2-6.8), and temperature (26.8-10.5 °C) and arsenic concentrations (169.5-44.0 nM) were higher than seawater. In the tissues of these organisms, the highest total measured As concentrations were in the gills of A. hessleri (5580 mg kg-1), with 721 mg kg-1 and 43 mg kg-1 in digestive gland and muscle, respectively. I. nautilei contained 118 mg kg-1 in the gill, 108 mg kg-1 in the digestive gland and 22 mg kg-1 in the muscle. B. manusensis contained 15.7 mg kg-1 in the digestive gland, followed by 9.8 mg kg-1 and 4.5 mg kg-1 in its gill and muscle tissue, respectively. We interpret the decreasing overall total concentrations in each organism as a function of distance from the source of hydrothermally derived As. The high concentration of arsenic in A. hessleri gills may be associated with elemental sulfur known to occur in this organism as a result of symbiotic microorganisms. Arsenic extracted from freeze-dried A. hessleri tissue was dominated by AsIII and AsV in the digestive gland (82% and 16%, respectively) and gills (97% AsIII, 2.3% AsV), with only 1.8% and 0.2% arsenobetaine (As-Bet) in the digestive gland and gills, respectively. However, the muscle contained substantial amounts of

Geologic form and setting of a hydrothermal vent field at lat 10°56‧N, East Pacific Rise: A detailed study using Angus and Alvin

NASA Astrophysics Data System (ADS)

McConachy, T. F.; Ballard, R. D.; Mottl, M. J.; von Herzen, R. P.

1986-04-01

A hydrothermal vent field, here called the Feather Duster site, occurs on the eastern marginal high near the edge of a narrow (95-m) and shallow (15 20-m) axial graben, within an area dominated by sheet flows and collapse features. The sheet flows are intermediate in relative age between younger fluid-flow lavas on the floor of the axial graben and older pillow (constructional) lavas on the marginal highs. Hydrothermal activity occurs in two zones within a 65 by 45 m area. The main zone is located where a fissure system and sulfide-sulfate chimneys vent warm (9 47 °C) and hot (347 °C) hydrothermal fluids. Here, two mounds of massive sulfide totaling about 200 t are forming. One occurs at the base of a 3-m-high scarp which is the wall of a drained lava lake; the other is perched on top of the scarp. *Present address: Department of Geology, University of Toronto, Toronto, Ontario, Canada M5S 1A1

Explosive Volcanic Eruptions from Linear Vents on Earth, Venus and Mars: Comparisons with Circular Vent Eruptions

NASA Technical Reports Server (NTRS)

Glaze, Lori S.; Baloga, Stephen M.; Wimert, Jesse

2010-01-01

Conditions required to support buoyant convective plumes are investigated for explosive volcanic eruptions from circular and linear vents on Earth, Venus, and Mars. Vent geometry (linear versus circular) plays a significant role in the ability of an explosive eruption to sustain a buoyant plume. On Earth, linear and circular vent eruptions are both capable of driving buoyant plumes to equivalent maximum rise heights, however, linear vent plumes are more sensitive to vent size. For analogous mass eruption rates, linear vent plumes surpass circular vent plumes in entrainment efficiency approximately when L(sub o) > 3r(sub o) owing to the larger entrainment area relative to the control volume. Relative to circular vents, linear vents on Venus favor column collapse and the formation of pyroclastic flows because the range of conditions required to establish and sustain buoyancy is narrow. When buoyancy can be sustained, however, maximum plume heights exceed those from circular vents. For current atmospheric conditions on Mars, linear vent eruptions are capable of injecting volcanic material slightly higher than analogous circular vent eruptions. However, both geometries are more likely to produce pyroclastic fountains, as opposed to convective plumes, owing to the low density atmosphere. Due to the atmospheric density profile and water content on Earth, explosive eruptions enjoy favorable conditions for producing sustained buoyant columns, while pyroclastic flows would be relatively more prevalent on Venus and Mars. These results have implications for the injection and dispersal of particulates into the planetary atmosphere and the ability to interpret the geologic record of planetary volcanism.

First hydrothermal active vent discovered on the Galapagos Microplate

NASA Astrophysics Data System (ADS)

Tao, C.; Li, H.; Wu, G.; Su, X.; Zhang, G.; Chinese DY115-21 Leg 3 Scientific Party

2011-12-01

The Galapagos Microplate (GM) lies on the western Gaplapagos Spreading Center (GSC), representing one of the classic Ridge-Ridge-Ridge (R-R-R) plate boundaries of the Nazca, Cocos, and Pacific plates. The presence of the 'black smoke' and hydrothermal vent community were firstly confirmed on the GSC. Lots of hydrothermal fields were discovered on the center and eastern GSC, while the western GSC has not been well investigated. During 17th Oct. to 9th Nov. 2009, the 3rd leg of Chinese DY115-21 cruise with R/V Dayangyihao has been launched along 2°N-5°S near equatorial East Pacific Rise (EPR). Two new hydrothermal fields were confirmed. One is named 'Precious Stone Mountain', which is the first hydrothermal field on the GM. The other is found at 101.47°W, 0.84°S EPR. The 'Precious Stone Mountain' hydrothermal field (at 101.49°W, 1.22°N) is located at an off-axial seamount on the southern GM boundary, with a depth from 1,450 to 1,700m. Hydrothermal fluids emitting from the fissures and hydrothermal fauna were captured by deep-tow video. Few mineral clasts of pyrite and chalcopyrite were separated from one sediment sample, but no sulfide chimney was found yet. Hydrothermal fauna such as alive mussels, crabs, shrimps, tubeworms, giant clams, as well as rock samples were collected by TV-Grab. The study of the seafloor classification with Simrad EM120 multi-beam echosounder has been conducted on the 'Precious Stone Mountain' hydrothermal field. The result indicates that seafloor materials around the hydrothermal field can be characterized into three types, such as the fresh lava, hydrothermal sediment, and altered rock.

Flank vents and graben as indicators of Late Amazonian volcanotectonic activity on Olympus Mons

NASA Astrophysics Data System (ADS)

Peters, S. I.; Christensen, P. R.

2017-03-01

Previous studies have focused on large-scale features on Olympus Mons, such as its flank terraces, the summit caldera complex, and the basal escarpment and aureole deposits. Here we identify and characterize previously unrecognized and unmapped small scale features to help further understand the volcanotectonic evolution of this enormous volcano. Using Context Camera, High Resolution Imaging Science Experiment, Thermal Emission Imaging System, High Resolution Stereo Camera Digital Terrain Model, and Mars Orbiter Laser Altimeter data, we identified and characterized the morphology and distribution of 60 flank vents and 84 grabens on Olympus Mons. We find that effusive eruptions have dominated volcanic activity on Olympus Mons in the Late Amazonian. Explosive eruptions were rare, implying volatile-poor magmas and/or a lack of magma-water interactions during the Late Amazonian. The distribution of flank vents suggests dike propagation of hundreds of kilometers and shallow magma storage. Small grabens, not previously observed in lower-resolution data, occur primarily on the lower flanks of Olympus Mons and indicate late-stage extensional tectonism. Based on superposition relationships, we have concluded two stages of development for Olympus Mons during the Late Amazonian: (1) primarily effusive resurfacing and formation of flank vents followed by (2) waning effusive volcanism and graben formation and/or reactivation. This developmental sequence resembles that proposed for Ascraeus Mons and other large Martian shields, suggesting a similar geologic evolution for these volcanoes.

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.

The Prevention of Ice Formation on Gasoline Tank Vents

NASA Technical Reports Server (NTRS)

Theodorsen, Theodore; Clay, William C

1931-01-01

This investigation was conducted in the refrigerated wind tunnel at the Langley Memorial Aeronautical Laboratory, Langley Field, Va., to determine a suitable method for preventing the formation of ice on the vents of airplane gasoline tanks. Tests were made on a variety of vent forms arranged in a number of different orientations relative to the direction of the air stream. Both the size of the tube and its orientation were found to be of great importance. Small tubes, under equal circumstances, were found to freeze over far more rapidly than large ones. Tubes pointing downstream, or shielded in other ways, appear to be perfectly immune against this hazard. A tube 3/4 inch in diameter with the opening pointing downstream is finally recommended as being the safest choice of gas tank vent.

Boiling vapour-type fluids from the Nifonea vent field (New Hebrides Back-Arc, Vanuatu, SW Pacific): Geochemistry of an early-stage, post-eruptive hydrothermal system

NASA Astrophysics Data System (ADS)

Schmidt, Katja; Garbe-Schönberg, Dieter; Hannington, Mark D.; Anderson, Melissa O.; Bühring, Benjamin; Haase, Karsten; Haruel, Christy; Lupton, John; Koschinsky, Andrea

2017-06-01

In 2013, high-temperature vent fluids were sampled in the Nifonea vent field. This field is located within the caldera of a large shield-type volcano of the Vate Trough, a young extensional rift in the New Hebrides back-arc. Hydrothermal venting occurs as clear and black smoker fluids with temperatures up to 368 °C, the hottest temperatures measured so far in the western Pacific. The physico-chemical conditions place the fluids within the two-phase field of NaCl-H2O, and venting is dominated by vapour phase fluids with Cl concentrations as low as 25 mM. The fluid composition, which differs between the individual vent sites, is interpreted to reflect the specific geochemical fluid signature of a hydrothermal system in its initial, post-eruptive stage. The strong Cl depletion is accompanied by low alkali/Cl ratios compared to more evolved hydrothermal systems, and very high Fe/Cl ratios. The concentrations of REY (180 nM) and As (21 μM) in the most Cl-depleted fluid are among the highest reported so far for submarine hydrothermal fluids, whereas the inter-element REY fractionation is only minor. The fluid signature, which has been described here for the first time in a back-arc setting, is controlled by fast fluid passage through basaltic volcanic rocks, with extremely high water-rock ratios and only limited water-rock exchange, phase separation and segregation, and (at least) two-component fluid mixing. Metals and metalloids are unexpectedly mobile in the vapour phase fluids, and the strong enrichments of Fe, REY, and As highlight the metal transport capacity of low-salinity, low-density vapours at the specific physico-chemical conditions at Nifonea. One possible scenario is that the fluids boiled before the separated vapour phase continued to react with fresh glassy lavas. The mobilization of metals is likely to occur by leaching from fresh glass and grain boundaries and is supported by the high water/rock ratios. The enrichment of B and As is further controlled

Repeat terrestrial lidar mapping of the new volcanic vent at Holuhraun, Iceland

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Whelley, P.; Sutton, S.; Needham, D. H.; Byrne, S.; Hamilton, C.

2016-12-01

The locations and morphologies of volcanic vents are essential observations that inform models of volcanic processes on Earth and other planets. Post-eruption morphologic changes at vents are important to characterize in order to more confidently use data gathered from mapping volcanic terrains. We present two terrestrial lidar surveys of the recently formed volcanic vent that fed the Holuhraun lava flow in the Northeastern Region of Iceland. While many studies have measured erosion rate at older volcanic vents, these surveys were performed 6 and 18 months after the end of the eruption and present an opportunity to measure morphologic changes at a brand-new vent. The Holuhraun eruption began in August 2014 by effusing lava through a fissure and continued until February 2015, emplacing approximately 1.4 km³ of lava over nearly 85 km². During the eruption the predominant activity at the northern end of the fissure produced a large (50 m high, 500 m long) cinder-canyon with scoria covered flanks. Lava ponded within this vent and drained to form a primary channel to the northeast. As lava drained through the channel, high stands of lava were preserved as "bathtub rings" on the walls of the vent. Following the cessation of activity at Holuhraun, two lidar surveys were carried out inside the vent, in August 2015 and August 2016. A Riegl VZ-400 scanner was used to collect the point cloud data, which give a precise 3D model of the vent with relative accuracy of 15 cm between scan positions. Differences between the two 3D point clouds are used to distinguish between flow emplacement and post-flow modifications to the surface, and to quantify the surface erosion rate experienced by the young vent. Near-infrared (1550 nm wavelength) reflectance values can also be correlated to lava textures and materials within the vent, providing additional information about how the vent was built syn-eruption and how it degrades post-eruption.

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.

Influence of Hydrodynamics on the Larval Supply to Hydrothermal Vents on the East Pacific Rise

DTIC Science & Technology

2007-06-01

field studies, this thesis first provides new morphological and genetic identifications for hydrothermal vent gastropod larvae along the northern East Pa...cific Rise. Daily and weekly variability in the supply of hydrothermal vent gastropod larvae to two hydrothermal vents, 1.6 km apart on the East...15 1.1 Thesis Organization ................................... 18 2 Morphological and molecular identification of gastropod larvae 23 2.1 Introduction

DUCKS: Low cost thermal monitoring units for near-vent deployment

NASA Astrophysics Data System (ADS)

Harris, Andrew; Pirie, Dawn; Horton, Keith; Garbeil, Harold; Pilger, Eric; Ramm, Hans; Hoblitt, Rick; Thornber, Carl; Ripepe, Maurizio; Marchetti, Emanuele; Poggi, Pasquale

2005-05-01

During 1999 we designed and tested a thermal monitoring system to provide a cheap, robust, modular, real-time system capable of surviving the hostile conditions encountered proximal to active volcanic vents. In November 2000 the first system was deployed at Pu'u 'O'o (Kilauea, Hawai'i) to target persistently active vents. Aside from some minor problems, such as sensor damage due to tampering, this system remained operational until January 2004. The success of the prototype system led us to use the blueprint for a second installation at Stromboli (Aeolian Islands, Italy). This was deployed, dug into a bomb-proof bunker, during May 2002 and survived the April 2003 paroxysmal eruption despite being located just 250 m from the vent. In both cases, careful waterproofing of connectors and selection of suitable protection has prevented water damage and corrosion in the harsh atmosphere encountered at the crater rim. The Pu'u 'O'o system cost ˜US10,000 and comprises four modules: sensors, transmission and power hub, repeater station and reception site. The sensor component consists of three thermal infrared thermometers housed in Pelican™ cases fitted with Germanium-Arsenide-Selenium windows. Two 1° field of view (FOV) sensors allow specific vents to be targeted and a 60° FOV sensor provides a crater floor overview. A hard wire connection links to a Pelican™-case-housed microprocessor, modem and power module. From here data are transmitted, via a repeater site, to a dedicated PC at the Hawaiian Volcano Observatory. Here data are displayed with a delay of ˜3 s between acquisition and display. The modular design allows for great flexibility. At Stromboli, 1° and 15° FOV sensor modules can be switched depending changes in activity style and crater geometry. In addition a direct line of site to the Stromboli reception center negates the repeater site requirement, reducing the cost to US5500 for a single sensor system. We have also constructed self-contained units

DUCKS: Low cost thermal monitoring units for near-vent deployment

USGS Publications Warehouse

Harris, A.; Pirie, D.; Horton, K.; Garbeil, H.; Pilger, E.; Ramm, H.; Hoblitt, R.; Thornber, C.; Ripepe, M.; Marchetti, E.; Poggi, P.

2005-01-01

During 1999 we designed and tested a thermal monitoring system to provide a cheap, robust, modular, real-time system capable of surviving the hostile conditions encountered proximal to active volcanic vents. In November 2000 the first system was deployed at Pu'u 'O'o (Kilauea, Hawai'i) to target persistently active vents. Aside from some minor problems, such as sensor damage due to tampering, this system remained operational until January 2004. The success of the prototype system led us to use the blueprint for a second installation at Stromboli (Aeolian Islands, Italy). This was deployed, dug into a bomb-proof bunker, during May 2002 and survived the April 2003 paroxysmal eruption despite being located just 250 m from the vent. In both cases, careful waterproofing of connectors and selection of suitable protection has prevented water damage and corrosion in the harsh atmosphere encountered at the crater rim. The Pu'u 'O'o system cost ???US$10,000 and comprises four modules: sensors, transmission and power hub, repeater station and reception site. The sensor component consists of three thermal infrared thermometers housed in Pelican??? cases fitted with Germanium-Arsenide-Selenium windows. Two 1?? field of view (FOV) sensors allow specific vents to be targeted and a 60?? FOV sensor provides a crater floor overview. A hard wire connection links to a Pelican???-case-housed microprocessor, modem and power module. From here data are transmitted, via a repeater site, to a dedicated PC at the Hawaiian Volcano Observatory. Here data are displayed with a delay of ???3 s between acquisition and display. The modular design allows for great flexibility. At Stromboli, 1?? and 15?? FOV sensor modules can be switched depending changes in activity style and crater geometry. In addition a direct line of site to the Stromboli reception center negates the repeater site requirement, reducing the cost to US$5500 for a single sensor system. We have also constructed self-contained units

The History of Venting (part I)

NASA Technical Reports Server (NTRS)

Leiter, Stephen C.

2017-01-01

Venting techniques and design are an important implementation strategy for observatory and payload contamination control, and yet venting analysis has seen a topsey turvey history, at lease from the perspective of the simple Layman trying to design a black box. Additionally, designing the vent has competing controls from Safety and EMIEMC. In the days of Shuttle, Safety placed liens against the vents of blankets, boxes, and large structural items principally to protect cargo bay vents but also from a flammability perspective. What continues to elude the Designer Community is a stable, simple way of designing vents for black boxes that satisfies everybody. But we continue to try.

Copepod colonization of organic and inorganic substrata at a deep-sea hydrothermal vent site on the Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Plum, Christoph; Pradillon, Florence; Fujiwara, Yoshihiro; Sarrazin, Jozée

2017-03-01

The few existing studies on deep-sea hydrothermal vent copepods indicate low connectivity with surrounding environments and reveal high endemism among vents. However, the finding of non-endemic copepod species in association with engineer species at different reduced ecosystems poses questions about the dispersal of copepods and the colonization of hydrothermal vents as well as their ecological connectivity. The objective of this study is to understand copepod colonization patterns at a hydrothermal vent site in response to environmental factors such as temperature and fluid flow as well as the presence of different types of substrata. To address this objective, an in situ experiment was deployed using both organic (woods, pig bones) and inorganic (slates) substrata along a gradient of hydrothermal activity at the Lucky Strike vent field (Eiffel Tower, Mid-Atlantic Ridge). The substrata were deployed in 2011 during the MoMARSAT cruise and were recovered after two years in 2013. Overall, copepod density showed significant differences between substrata types, but was similar among different hydrothermal activity regimes. Highest densities were observed on woods at sites with moderate or low fluid input, whereas bones were the most densely colonized substrata at the 2 sites with higher hydrothermal influence. Although differences in copepod diversity were not significant, the observed trends revealed overall increasing diversity with decreasing temperature and fluid input. Slates showed highest diversity compared to the organic substrata. Temperature and fluid input had a significant influence on copepod community composition, resulting in higher similarity among stations with relatively high and low fluid inputs, respectively. While vent-specialists such as dirivultids and the tegastid Smacigastes micheli dominated substrata at high vent activity, the experiment demonstrated increasing abundance and dominance of non-vent taxa with decreasing temperature and fluid

The Origin of Life in Alkaline Hydrothermal Vents.

PubMed

Sojo, Victor; Herschy, Barry; Whicher, Alexandra; Camprubí, Eloi; Lane, Nick

2016-02-01

Over the last 70 years, prebiotic chemists have been very successful in synthesizing the molecules of life, from amino acids to nucleotides. Yet there is strikingly little resemblance between much of this chemistry and the metabolic pathways of cells, in terms of substrates, catalysts, and synthetic pathways. In contrast, alkaline hydrothermal vents offer conditions similar to those harnessed by modern autotrophs, but there has been limited experimental evidence that such conditions could drive prebiotic chemistry. In the Hadean, in the absence of oxygen, alkaline vents are proposed to have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with relatively acidic ocean waters rich in CO2, through a labyrinth of interconnected micropores with thin inorganic walls containing catalytic Fe(Ni)S minerals. The difference in pH across these thin barriers produced natural proton gradients with equivalent magnitude and polarity to the proton-motive force required for carbon fixation in extant bacteria and archaea. How such gradients could have powered carbon reduction or energy flux before the advent of organic protocells with genes and proteins is unknown. Work over the last decade suggests several possible hypotheses that are currently being tested in laboratory experiments, field observations, and phylogenetic reconstructions of ancestral metabolism. We analyze the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria to propose a possible ancestral mechanism of CO2 reduction in alkaline hydrothermal vents. Based on this mechanism, we show that the evolution of active ion pumping could have driven the deep divergence of bacteria and archaea.

Design and integrated operation of an innovative thermodynamic vent system concept

NASA Astrophysics Data System (ADS)

Fazah, Michel M.; Lak, Tibor; Nguyen, Han; Wood, Charles C.

1993-06-01

A unique zero-g thermodynamic vent system (TVS) is being developed by NASA's Marshall Space Flight Center (MSFC) and Rockwell International to meet cryogenic propellant management requirements for future space missions. The design is highly innovative in that it integrates the functions of a spray-bar tank mixer and a TVS. This concept not only satisfies the requirement for efficient tank mixing and zero-g venting but also accommodates thermal conditioning requirements for other components (e.g., engine feed lines, turbopumps, and liquid acquisition devices). In addition, operations can be extended to accomplish tank chill-down, no-vent fill, and emergency venting during zero-g propellant transfer. This paper describes the system performance characterization and future test activities that are part of MSFC's Multipurpose Hydrogen Test Bed (MHTB) program. The testing will demonstrate the feasibility and merit of the design, and serve as a proof-of-concept development activity.

33 CFR 159.61 - Vents.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.61 Vents. Vents must be designed and constructed...

Geophysical Signatures of cold vents on the northern Cascadia margin

NASA Astrophysics Data System (ADS)

Riedel, M.; Paull, C. K.; Spence, G.; Hyndman, R. D.; Caress, D. W.; Thomas, H.; Lundsten, E.; Ussler, W.; Schwalenberg, K.

2009-12-01

The accretionary prism of the northern Cascadia margin is a classic gas hydrate research area. Ocean Drilling Program Leg 146 and Integrated Ocean Drilling Program (IODP) Expedition 311 documented that gas hydrate is widely distributed across the margin. In recent years an increased research focus has been on cold vents, where methane gas is actively released. Two recent expeditions funded by the Monterey Bay Aquarium Research Institute (MBARI) were conducted in the area of IODP Sites U1327 and U1328. An autonomous underwater vehicle (AUV) was used to map the seafloor bathymetry followed by dives with the ROV Doc Ricketts for ground truth information of various seafloor morphological features identified. The two cruises revealed many new seafloor features indicative of methane venting that were previously unknown. Bullseye Vent (BV) has been extensively studied using seismic imaging, piston coring, heat-flow, controlled-source EM, and deep drilling. BV is seismically defined by a circular wipe-out zone but the new AUV data show that BV is rather an elongated depression. BV is associated with a shoaling in the BSR, but lacks evidence for the existence of an underlying fault in the previous data. Although a massive gas-hydrate plug was encountered within the top 40 mbsf in the IODP holes, the ROV observations only revealed some platy methane derived carbonate outcrops at the outer-most rim of the depressions, a few beds of Vesicomya clams, and no observed gas vents, which together do not indicate that BV is especially active now. Further northeast of BV, but along the same trend, active gas venting was found associated with seafloor blistering and bacterial mats suggesting that there is an underlying fault system providing a fluid flow conduit. The newly discovered vent area has few seismic line crossings; however the available seismic data surprisingly are not associated with wipe-out zones. Another prominent fault-related gas vent also was investigated during the

Microbial community structure and functioning in marine sediments associated with diffuse hydrothermal venting assessed by integrated meta-omics.

PubMed

Urich, Tim; Lanzén, Anders; Stokke, Runar; Pedersen, Rolf B; Bayer, Christoph; Thorseth, Ingunn H; Schleper, Christa; Steen, Ida H; Ovreas, Lise

2014-09-01

Deep-sea hydrothermal vents are unique environments on Earth, as they host chemosynthetic ecosystems fuelled by geochemical energy with chemolithoautotrophic microorganisms at the basis of the food webs. Whereas discrete high-temperature venting systems have been studied extensively, the microbiotas associated with low-temperature diffuse venting are not well understood. We analysed the structure and functioning of microbial communities in two diffuse venting sediments from the Jan Mayen vent fields in the Norwegian-Greenland Sea, applying an integrated 'omics' approach combining metatranscriptomics, metaproteomics and metagenomics. Polymerase chain reaction-independent three-domain community profiling showed that the two sediments hosted highly similar communities dominated by Epsilonproteobacteria, Deltaproteobacteria and Gammaproteobacteria, besides ciliates, nematodes and various archaeal taxa. Active metabolic pathways were identified through transcripts and peptides, with genes of sulphur and methane oxidation, and carbon fixation pathways highly expressed, in addition to genes of aerobic and anaerobic (nitrate and sulphate) respiratory chains. High expression of chemotaxis and flagella genes reflected a lifestyle in a dynamic habitat rich in physico-chemical gradients. The major metabolic pathways could be assigned to distinct taxonomic groups, thus enabling hypotheses about the function of the different prokaryotic and eukaryotic taxa. This study advances our understanding of the functioning of microbial communities in diffuse hydrothermal venting sediments. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Numerous Submarine Radial Vents Revealed on Mauna Loa Volcano

NASA Astrophysics Data System (ADS)

Wanless, D.; Garcia, M. O.; Rhodes, J. M.; Trusdell, F. A.; Schilling, S.; Weis, D.; Fornari, D.; Vollinger, M.

2003-12-01

Among Hawaiian shield volcanoes, Mauna Loa is distinct in having vents outside of its summit and rift zones. These radial vents are located on its northern and western flanks and account for approximately 10% of historic eruptions outside the summit region. Thirty-three subaerial and one submarine vent (active in 1877) were known prior to our work. During a recent Jason2 expedition to the volcano's western flank, nine new submarine radial vents were discovered. Eighty-five samples were collected from these and the 1877 radial vent. Bathymetry and side-scan imagery were acquired using an EM300 multibeam echo sounder. The high resolution data (vertical resolution of approximately 4 m and horizontal resolution of 25 m) allowed us to create the first detailed geologic map of Mauna Loa's western submarine flank. The map was compiled using video and still photography from the Jason2 ROV and geochemical analysis of the samples. The geochemistry includes microprobe glass and XRF whole rock major and trace element data. Eight of the submarine radial vents sampled erupted tholeiitic lavas that are geochemically similar to historical subaerial eruptions on Mauna Loa. However, in contrast to all previously collected Mauna Loa lavas, two of the young vents erupted alkalic basalts. These lavas may have been derived from Mauna Loa, as they have somewhat higher FeO and TiO2 values at a given MgO content than alkalic lavas from neighboring Hualalai volcano, whose vents are located only on rifts 16 km away. Alkalic lavas are indicative of the postshield stage of volcanism and may signal the impending demise of Mauna Loa volcano.

Genomic variation of subseafloor archaeal and bacterial populations from venting fluids at the Mid-Cayman Rise

NASA Astrophysics Data System (ADS)

Anderson, R. E.; Eren, A. M.; Stepanauskas, R.; Huber, J. A.; Reveillaud, J.

2015-12-01

Deep-sea hydrothermal vent systems serve as windows to a dynamic, gradient-dominated deep biosphere that is home to a wide diversity of archaea, bacteria, and viruses. Until recently the majority of these microbial lineages were uncultivated, resulting in a poor understanding of how the physical and geochemical context shapes microbial evolution in the deep subsurface. By comparing metagenomes, metatranscriptomes and single-cell genomes between geologically distinct vent fields, we can better understand the relationship between the environment and the evolution of subsurface microbial communities. An ideal setting in which to use this approach is the Mid-Cayman Rise, located on the world's deepest and slowest-spreading mid-ocean ridge, which hosts both the mafic-influenced Piccard and ultramafic-influenced Von Damm vent fields. Previous work has shown that Von Damm has higher taxonomic and metabolic diversity than Piccard, consistent with geochemical model expectations, and the fluids from all vents are enriched in hydrogen (Reveillaud et al., submitted). Mapping of both metagenomes and metatranscriptomes to a combined assembly showed very little overlap among the Von Damm samples, indicating substantial variability that is consistent with the diversity of potential metabolites in this ultramafic vent field. In contrast, the most consistently abundant and active lineage across the Piccard samples was Sulfurovum, a sulfur-oxidizing chemolithotroph that uses nitrate or oxygen as an electron acceptor. Moreover, analysis of point mutations within individual lineages suggested that Sulfurovumat Piccard is under strong selection, whereas microbial genomes at Von Damm were more variable. These results are consistent with the hypothesis that the subsurface environment at Piccard supports the emergence of a dominant lineage that is under strong selection pressure, whereas the more geochemically diverse microbial habitat at Von Damm creates a wider variety of stable

Virtual Vents: A Microbathymetrical Survey of the Niua South Hydrothermal Field, NE Lau Basin, Tonga

NASA Astrophysics Data System (ADS)

Kwasnitschka, T.; Köser, K.; Duda, A.; Jamieson, J. W.; Boschen, R.; Gartman, A.; Hannington, M. D.; Funganitao, C.

2016-12-01

At a diameter of 200 m, the 1100 m deep Niua South hydrothermal field (NE Lau Basin) was studied in an interdisciplinary approach during the SOI funded Virtual Vents cruise in March of 2016. On the grounds of a previously generated 50 cm resolution AUV multi beam map, the projects backbone is formed by a fully color textured, 5 cm resolution photogrammetrical 3D model. Several hundred smaller and about 15 chimneys larger than 3 m were surveyed including their basal mounds and surrounding environment interconnecting to each other. This model was populated through exhaustive geological, biological and fluid sampling as well as continuous Eh measurements, forming the basis for highly detailed geological structural and biological studies resulting in 3D maps of the entire field. At a reasonable effort, such surveys form the basis for repetitive time series analysis and have the potential of a new standard in seafloor monitoring.

The Sound Generated by Mid-Ocean Ridge Black Smoker Hydrothermal Vents

PubMed Central

Crone, Timothy J.; Wilcock, William S.D.; Barclay, Andrew H.; Parsons, Jeffrey D.

2006-01-01

Hydrothermal flow through seafloor black smoker vents is typically turbulent and vigorous, with speeds often exceeding 1 m/s. Although theory predicts that these flows will generate sound, the prevailing view has been that black smokers are essentially silent. Here we present the first unambiguous field recordings showing that these vents radiate significant acoustic energy. The sounds contain a broadband component and narrowband tones which are indicative of resonance. The amplitude of the broadband component shows tidal modulation which is indicative of discharge rate variations related to the mechanics of tidal loading. Vent sounds will provide researchers with new ways to study flow through sulfide structures, and may provide some local organisms with behavioral or navigational cues. PMID:17205137

First columbellid species (Gastropoda: Buccinoidea) from deep-sea hydrothermal vents, discovered in Okinawa Trough, Japan.

PubMed

Chen, Chong; Watanabe, Hiromi Kayama; Araya, Juan Francisco

2017-12-12

The molluscan diversity of deep-sea chemosynthetic ecosystems in Japan has been in general well documented with about 80 described species, of which over half are gastropods (Sasaki et al. 2005; Fujikura et al. 2012; Sasaki et al. 2016). Recently, however, a number of novel hydrothermal vent sites were discovered in the area using multibeam echo-sounding (Nakamura et al. 2015), providing opportunities for new discoveries. As a part of ongoing studies documenting the biodiversity of such sites, we present the first record of Columbellidae from hydrothermal vents, with a new species recovered from Natsu and Aki sites, in the Iheya North hydrothermal field (for map and background on the vent field see Nakamura et al. 2015).

Evaluation of aperture cover tank vent nozzles for the IRAS spacecraft

NASA Technical Reports Server (NTRS)

Richter, R.

1983-01-01

The influence of coefficients for the three axes of the Infrared Astronomical Satellite (IRAS) were established to determine the maximum allowable thrust difference between the two vent nozzles of the aperture cover tank low thrust vent system and their maximum misalignment. Test data generated by flow and torque measurements permitted the selection of two nozzles whose thrust differential was within the limit of the attitude control capability. Based on thrust stand data, a thrust vector misalignment was indicated that was slightly higher than permissible for the worst case, i.e., considerable degradation of the torque capacity of the attitude control system combined with venting of helium at its upper limit. The probability of destabilizing the IRAS spacecraft by activating the venting system appeared to be very low. The selection and mounting of the nozzles have satisfied all the requirements for the safe venting of helium.

3D Photo Mosaicing of Tagiri Shallow Vent Field by an Autonomous Underwater Vehicle

NASA Astrophysics Data System (ADS)

Maki, Toshihiro; Kondo, Hayato; Ura, Tamaki; Sakamaki, Takashi; Mizushima, Hayato; Yanagisawa, Masao

Although underwater visual observation is an ideal method for detailed survey of seafloors, it is currently a costly process that requires the use of Remotely Operated Vehicles (ROVs) or Human Occupied Vehicles (HOVs), and can cover only a limited area. This paper proposes an innovative method to navigate an autonomous underwater vehicle (AUV) to create both 2D and 3D photo mosaics of seafloors with high positioning accuracy without using any vision-based matching. The vehicle finds vertical pole-like acoustic reflectors to use as positioning landmarks using a profiling sonar based on a SLAM (Simultaneous Localization And Mapping) technique. These reflectors can be either artificial or natural objects, and so the method can be applied to shallow vent fields where conventional acoustic positioning is difficult, since bubble plumes can also be used as landmarks as well as artificial reflectors. Path-planning is performed in real-time based on the positions and types of landmarks so as to navigate safely and stably using landmarks of different types (artificial reflector or bubble plume) found at arbitrary times and locations. Terrain tracker switches control reference between depth and altitude from the seafloor based on a local map of hazardous area created in real-time using onboard perceptual sensors, in order to follow rugged terrains at an altitude of 1 to 2 meters, as this range is ideal for visual observation. The method was implemented in the AUV Tri-Dog 1 and experiments were carried out at Tagiri vent field, Kagoshima Bay in Japan. The AUV succeeded in fully autonomous observation for more than 160 minutes to create a photo mosaic with an area larger than 600 square meters, which revealed the spatial distribution of detailed features such as tube-worm colonies, bubble plumes and bacteria mats. A fine bathymetry of the same area was also created using a light-section ranging system mounted on the vehicle. Finally a 3 D representation of the environment was

Previously unsuspected dietary habits of hydrothermal vent fauna: the bactivorous shrimp Rimicaris hybisae can be carnivorous or even cannibalistic

NASA Astrophysics Data System (ADS)

Versteegh, Emma; Van Dover, Cindy; Coleman, Max

2014-05-01

Most hydrothermal vents support productive communities, with chemosynthetic bacteria at the base of the food web. They form a potentially important link in global geochemical cycles. However, few data yet exist on their significance in ocean biogeochemistry and related ecological processes. We present results on the structure of part of the food web around hydrothermal vents of the Mid-Cayman Rise (MCR), revealing previously unknown life-history traits of the alvinocarid shrimp species Rimicaris hybisae. We also demonstrate that stable carbon isotope ratios (δ13C values) are an excellent tracer of trophic positions in these ecosystems, in spite of recent findings arguing otherwise. Two hydrothermal vent fields have been described at the ultra-slow spreading ridge of the MCR. These include the world's deepest hydrothermal vents (Piccard field ~4985 m), which support a food web, which includes bactivorous shrimp and carnivorous anemones. The nearby Von Damm vent field (~2300 m) supports a more complex food web, with more primary producers, and probably some influx of photosynthetically produced carbon. Rimicaris hybisae is abundant at both known MCR vent fields and shows a high degree of spatial variability in population structure and reproductive features. In previous work it has been considered bactivorous. Large variations in tissue δ13C values remained largely unexplained, and it has been argued that δ13C values are not a good food web tracer in hydrothermal vent ecosystems. We observed that shrimp tended to be either in dense aggregations on active chimneys or more sparsely distributed, peripheral shrimp in ambient or near-ambient temperatures. With the hypothesis that varying δ13C values show real differences in food sources between individuals and that shrimp in different locales might have different diets, we collected shrimp from both environments at the Von Damm site during E/V Nautilus (NA034, August 2013) and examined their gut contents. Stomach

Detecting the Influence of Initial Pioneers on Succession at Deep-Sea Vents

PubMed Central

Mullineaux, Lauren S.; Le Bris, Nadine; Mills, Susan W.; Henri, Pauline; Bayer, Skylar R.; Secrist, Richard G.; Siu, Nam

2012-01-01

Deep-sea hydrothermal vents are subject to major disturbances that alter the physical and chemical environment and eradicate the resident faunal communities. Vent fields are isolated by uninhabitable deep seafloor, so recolonization via dispersal of planktonic larvae is critical for persistence of populations. We monitored colonization near 9°50′N on the East Pacific Rise following a catastrophic eruption in order to address questions of the relative contributions of pioneer colonists and environmental change to variation in species composition, and the role of pioneers at the disturbed site in altering community structure elsewhere in the region. Pioneer colonists included two gastropod species: Ctenopelta porifera, which was new to the vent field, and Lepetodrilus tevnianus, which had been rare before the eruption but persisted in high abundance afterward, delaying and possibly out-competing the ubiquitous pre-eruption congener L. elevatus. A decrease in abundance of C. porifera over time, and the arrival of later species, corresponded to a decrease in vent fluid flow and in the sulfide to temperature ratio. For some species these successional changes were likely due to habitat requirements, but other species persisted (L. tevnianus) or arrived (L. elevatus) in patterns unrelated to their habitat preferences. After two years, disturbed communities had started to resemble pre-eruption ones, but were lower in diversity. When compared to a prior (1991) eruption, the succession of foundation species (tubeworms and mussels) appeared to be delayed, even though habitat chemistry became similar to the pre-eruption state more quickly. Surprisingly, a nearby community that had not been disturbed by the eruption was invaded by the pioneers, possibly after they became established in the disturbed vents. These results indicate that the post-eruption arrival of species from remote locales had a strong and persistent effect on communities at both disturbed and undisturbed

Are vent crab behavioral preferences adaptations for habitat choice?

PubMed

Dahms, Hans-Uwe; Tseng, Li-Chun; Hwang, Jiang-Shiou

2017-01-01

were always consistent with the side of the choice compartment in which they spent the longest amount of time (resident time), but not with the 'final choice' of crabs, suggesting that the 'resident time' in addition to their 'first choice' is more reliable than just the 'final choice'. The present results provide the first indication that several vent-associated habitat cues function as attractors for HV crabs. Habitat choice is also reflected by crab larval distribution in the field which tend to stay near the bottom not to be carried away from their specific habitat.

Measure Guideline: Passive Vents

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

Berger, David; Neri, Robin

2016-02-05

This document addresses the use of passive vents as a source of outdoor air in multifamily buildings. The challenges associated with implementing passive vents and the factors affecting performance are outlined. A comprehensive design methodology and quantified performance metrics are provided. Two hypothetical design examples are provided to illustrate the process. This document is intended to be useful to designers, decision-makers, and contractors implementing passive ventilation strategies. It is also intended to be a resource for those responsible for setting high-performance building program requirements, especially pertaining to ventilation and outdoor air. To ensure good indoor air quality, a dedicated sourcemore » of outdoor air is an integral part of high-performance buildings. Presently, there is a lack of guidance pertaining to the design and installation of passive vents, resulting in poor system performance. This report details the criteria necessary for designing, constructing, and testing passive vent systems to enable them to provide consistent and reliable levels of ventilation air from outdoors.« less

40 CFR 63.983 - Closed vent systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Closed vent systems. 63.983 Section 63... Emission Standards for Closed Vent Systems, Control Devices, Recovery Devices and Routing to a Fuel Gas System or a Process § 63.983 Closed vent systems. (a) Closed vent system equipment and operating...

Behavioural study of two hydrothermal crustacean decapods: Mirocaris fortunata and Segonzacia mesatlantica, from the Lucky Strike vent field (Mid-Atlantic Ridge)

NASA Astrophysics Data System (ADS)

Matabos, M.; Cuvelier, D.; Brouard, J.; Shillito, B.; Ravaux, J.; Zbinden, M.; Barthelemy, D.; Sarradin, P. M.; Sarrazin, J.

2015-11-01

Identifying the factors driving community dynamics in hydrothermal vent communities, and in particular biological interactions, is challenged by our ability to make direct observations and the difficulty to conduct experiments in those remote ecosystems. As a result, we have very limited knowledge on species' behaviour and interactions in these communities and how they in turn influence community dynamics. Interactions such as competition or predation significantly affect community structure in vent communities, and video time-series have successfully been used to gain insights in biological interactions and species behaviour, including responses to short-term changes in temperature or feeding strategies. In this study, we combined in situ and ex situ approaches to characterise the behaviour and interactions among two key species encountered along the Mid-Atlantic Ridge (MAR): the shrimp Mirocaris fortunata and the crab Segonzacia mesatlantica. In situ, species small-scale distribution, interactions and behaviour were studied using the TEMPO observatory module deployed on the seafloor at the base of the active Eiffel Tower edifice in the Lucky Strike vent field as part of the EMSO-Açores MoMAR observatory. TEMPO sampled 2 min of video four times a day from July 2011 to April 2012. One week of observations per month was used for 'long-term' variations, and a full video data set was analysed for January 2012. In addition, observations of crab and shrimp individuals maintained for the first time under controlled conditions in atmospheric pressure (classic tank) and pressurised (AbyssBox) aquaria allowed better characterisation and description of the different types of behaviour and interactions observed in nature. While the identified in situ spatial distribution pattern was stable over the nine months, both species displayed a significant preference for mussel bed and anhydrite substrata, and preferentially occupied the area located directly in the fluid flow axis

DETAIL OF WEST END SLIDING DOOR AND EAVE VENTS ON ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL OF WEST END SLIDING DOOR AND EAVE VENTS ON THE SOUTH SIDE - Hickam Field, Practice Bomb Loading Shed, Bomb Storage Road near the intersection of Moffet and Kamakahi Streets, Honolulu, Honolulu County, HI

Differences in recovery between deep-sea hydrothermal vent and vent-proximate communities after a volcanic eruption

NASA Astrophysics Data System (ADS)

Gollner, Sabine; Govenar, Breea; Arbizu, Pedro Martinez; Mills, Susan; Le Bris, Nadine; Weinbauer, Markus; Shank, Timothy M.; Bright, Monika

2015-12-01

Deep-sea hydrothermal vents and the surrounding basalt seafloor are subject to major natural disturbance events such as volcanic eruptions. In the near future, anthropogenic disturbance in the form of deep-sea mining could also significantly affect the faunal communities of hydrothermal vents. In this study, we monitor and compare the recovery of insular, highly productive vent communities and vent-proximate basalt communities following a volcanic eruption that destroyed almost all existing communities at the East Pacific Rise, 9°50‧N in 2006. To study the recovery patterns of the benthic communities, we placed settlement substrates at vent sites and their proximate basalt areas and measured the prokaryotic abundance and compared the meio- and macrofaunal species richness and composition at one, two and four years after the eruption. In addition, we collected samples from the overlying water column with a pelagic pump, at one and two years after the volcanic eruption, to determine the abundance of potential meiofauna colonisers. One year after eruption, mean meio- and macrofaunal abundances were not significantly different from pre-eruption values in vent habitats (meio: 8-1838 ind. 64 cm-2 in 2006; 3-6246 ind. 64 cm-2 in 2001/02; macro: 95-1600 ind. 64 cm-2 in 2006; 205-4577 ind. 64 cm-2 in 2001/02) and on non-vent basalt habitats (meio: 10-1922 ind. 64 cm-2 in 2006; 8-328 ind. 64 cm-2 in 2003/04; macro: 14-3351 ind. 64 cm-2 in 2006; 2-63 ind. 64 cm-2 in 2003/04), but species recovery patterns differed between the two habitat types. In the vent habitat, the initial community recovery was relatively quick but incomplete four years after eruption, which may be due to the good dispersal capabilities of vent endemic macrofauna and vent endemic dirivultid copepods. At vents, 42% of the pre-eruption meio- and 39% of macrofaunal species had returned. In addition, some new species not evident prior to the eruption were found. At the tubeworm site Tica, a total of 26

Low Gravity venting of Refrigerant 11

NASA Technical Reports Server (NTRS)

Labus, T. L.; Aydelott, J. C.; Lacovic, R. F.

1972-01-01

An experimental investigation was conducted in a five-second zero gravity facility to examine the effects of venting initially saturated Refrigerant 11 from a cylindrical container (15-cm diameter) under reduced gravitational conditions. The system Bond numbers studied were 0 (weightlessness), 9 and 63; the liquid exhibited a nearly zero-degree contact angle on the container surface. During the venting process, both liquid-vapor interface and liquid bulk vaporization occurred. The temperature of the liquid in the immediate vicinity of the liquid-vapor interface was found to decrease during venting, while the liquid bulk temperature remained constant. Qualitative observations of the effects of system acceleration, vent rate, and vapor volume presented. Quantitative information concerning the ullage pressure decay during low gravity venting is also included.

40 CFR 65.62 - Process vent group determination.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., or Group 2B) for each process vent. Group 1 process vents require control, and Group 2A and 2B... 40 Protection of Environment 15 2010-07-01 2010-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a) Group...

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2010 CFR

2010-04-01

... be DWV grade nylon or acetal; (iii) Spring shall be stainless steel wire, type 302; (iv) Sealing disc...) Materials—(1) Pipe. Vent piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed...

24 CFR 3280.611 - Vents and venting.

Code of Federal Regulations, 2011 CFR

2011-04-01

... be DWV grade nylon or acetal; (iii) Spring shall be stainless steel wire, type 302; (iv) Sealing disc...) Materials—(1) Pipe. Vent piping shall be standard weight steel, wrought iron, brass, copper tube DWV, listed...

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

PubMed

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

2003-07-25

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

The origin of life in alkaline hydrothermal vents

NASA Astrophysics Data System (ADS)

Sojo, V.; Herschy, B.; Whicher, A.; Camprubí, E.; Lane, N.

2016-12-01

The origin of life remains one of Science's greatest unresolved questions. The answer will no doubt involve almost all the basic disciplines, including Physics, Chemistry, Astronomy, Geology, and Biology. Chiefly, it is the link between the latter two that must be elucidated: how geochemistry gave rise to biochemistry. Serpentinizing systems such as alkaline hydrothermal vents offer the most robust combination of conditions to have hosted the origin of life on the early Earth, while bearing many parallels to modern living cells. Stark gradients of concentration, pH, oxidation/reduction, and temperature provided the ability to synthesise and concentrate organic products, drive polymerisation reactions, and develop an autotrophic lifestyle independent of foreign sources of organics. In the oxygen-depleted waters of the Hadean, alkaline vents would have acted as electrochemical flow reactors, in which alkaline fluids saturated in H2 mixed with the relatively acidic CO2-rich waters of the ocean, through interconnected micropores made of thin inorganic walls containing catalytic Fe(Ni)S minerals. Perhaps not coincidentally, the unit cells of these Fe(Ni)S minerals closely resemble the active sites of crucial ancestral bioenergetic enzymes. Meanwhile, differences in pH across the thin barriers produced natural proton gradients similar to those used for carbon fixation in modern archaea and bacteria. At the earliest stages, the problem of the origin of life is the problem of the origin of carbon fixation. I will discuss work over the last decade that suggests several possible hypotheses for how simple one-carbon molecules could have given rise to more complex organics, particularly within a serpentinizing alkaline hydrothermal vent. I will discuss the perplexing differences in carbon and energy metabolism in methanogenic archaea and acetogenic bacteria, thought to be the earliest representatives of each domain, to propose a possible ancestral mechanism of CO2 reduction in

Identification of possible recent water/lava source vents in the Cerberus plains: Stratigraphic andcrater count age constraints

NASA Astrophysics Data System (ADS)

Thomas, Rebecca J.

2013-04-01

In order to investigate sources of lava and water to the Cerberus plains of Mars, geomorphological mapping on High Resolution Imaging Science Experiment (HiRISE) images was carried out to reveal the history of activity of fissures and pits which lie upstream of channels and deposits associated with a wrinkle ridge near Cerberus Fossae. The fissures and pits are superbly exposed and imaged, and flows and channels emanate directly from them, interpreted as clear evidence that these are vents. The mapping establishes stratigraphic relationships between the plains and the channels and deposits originating from the vents, establishing the vent history. For example, to the south of the wrinkle ridge, both incised channels and leveed flows extend onto the southern plain and are clearly the final phase of plains-forming activity. Conversely, to the north, vent-sourced channels only incise the plain close to the ridge—beyond that, they are overlain by large-scale regional flows that appear to have originated from the direction of Athabasca Valles. In the southeast, there is evidence of contemporaneity between vent-sourced activity and large-scale plains-forming flow that was not sourced from the vents, indicating that activity here was part of a broader process of Cerberus plains formation from multiple sources. Crater counts show all the activity to be Late Amazonian, with the latest activity tentatively dating to circa 11 Ma. Thus, this study implies that very recent outflows from these vents contributed to the formation of the Cerberus plains and constrains the timing and local flow direction of plains-forming deposits from other sources.

Microbial analysis of Zetaproteobacteria and co-colonizers of iron mats in the Troll Wall Vent Field, Arctic Mid-Ocean Ridge

PubMed Central

Vander Roost, Jan; Thorseth, Ingunn Hindenes

2017-01-01

Over the last decade it has become increasingly clear that Zetaproteobacteria are widespread in hydrothermal systems and that they contribute to the biogeochemical cycling of iron in these environments. However, how chemical factors control the distribution of Zetaproteobacteria and their co-occurring taxa remains elusive. Here we analysed iron mats from the Troll Wall Vent Field (TWVF) located at the Arctic Mid-Ocean Ridge (AMOR) in the Norwegian-Greenland Sea. The samples were taken at increasing distances from high-temperature venting chimneys towards areas with ultraslow low-temperature venting, encompassing a large variety in geochemical settings. Electron microscopy revealed the presence of biogenic iron stalks in all samples. Using 16S rRNA gene sequence profiling we found that relative abundances of Zetaproteobacteria in the iron mats varied from 0.2 to 37.9%. Biogeographic analyses of Zetaproteobacteria, using the ZetaHunter software, revealed the presence of ZetaOtus 1, 2 and 9, supporting the view that they are cosmopolitan. Relative abundances of co-occurring taxa, including Thaumarchaeota, Euryarchaeota and Proteobacteria, also varied substantially. From our results, combined with results from previous microbiological and geochemical analyses of the TWVF, we infer that the distribution of Zetaproteobacteria is connected to fluid-flow patterns and, ultimately, variations in chemical energy landscapes. Moreover, we provide evidence for iron-oxidizing members of Gallionellaceae being widespread in TWVF iron mats, albeit at low relative abundances. PMID:28931087

46 CFR 153.354 - Venting system inlet.

Code of Federal Regulations, 2013 CFR

2013-10-01

... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.354 Venting system inlet. A venting system must terminate in the vapor space above the cargo...

46 CFR 153.354 - Venting system inlet.

Code of Federal Regulations, 2012 CFR

2012-10-01

... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.354 Venting system inlet. A venting system must terminate in the vapor space above the cargo...

46 CFR 153.354 - Venting system inlet.

Code of Federal Regulations, 2010 CFR

2010-10-01

... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.354 Venting system inlet. A venting system must terminate in the vapor space above the cargo...

46 CFR 153.354 - Venting system inlet.

Code of Federal Regulations, 2014 CFR

2014-10-01

... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.354 Venting system inlet. A venting system must terminate in the vapor space above the cargo...

46 CFR 153.354 - Venting system inlet.

Code of Federal Regulations, 2011 CFR

2011-10-01

... BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design and Equipment Cargo Venting Systems § 153.354 Venting system inlet. A venting system must terminate in the vapor space above the cargo...

A biogeographic network reveals evolutionary links between deep-sea hydrothermal vent and methane seep faunas

PubMed Central

2016-01-01

Deep-sea hydrothermal vents and methane seeps are inhabited by members of the same higher taxa but share few species, thus scientists have long sought habitats or regions of intermediate character that would facilitate connectivity among these habitats. Here, a network analysis of 79 vent, seep, and whale-fall communities with 121 genus-level taxa identified sedimented vents as a main intermediate link between the two types of ecosystems. Sedimented vents share hot, metal-rich fluids with mid-ocean ridge-type vents and soft sediment with seeps. Such sites are common along the active continental margins of the Pacific Ocean, facilitating connectivity among vent/seep faunas in this region. By contrast, sedimented vents are rare in the Atlantic Ocean, offering an explanation for the greater distinction between its vent and seep faunas compared with those of the Pacific Ocean. The distribution of subduction zones and associated back-arc basins, where sedimented vents are common, likely plays a major role in the evolutionary and biogeographic connectivity of vent and seep faunas. The hypothesis that decaying whale carcasses are dispersal stepping stones linking these environments is not supported. PMID:27974524

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

Evaluation of Soil Venting Application

EPA Pesticide Factsheets

The ability of soil venting to inexpensively remove large amounts of volatile organic compounds (VOCs) from contaminated soils is well established. However, the time required using venting to remediate soils to low contaminant levels often required by..

Integration of video and infrasound to understand source locations and vent geometry at Erebus Volcano, Antarctica

NASA Astrophysics Data System (ADS)

Jones, K. R.; Aster, R. C.; Johnson, J. B.; Kyle, P. R.; McIntosh, W. C.

2007-05-01

Infrasound monitoring at Erebus volcano has enabled us to quantify eruption energetics and precisely determine the source location of Strombolian eruptions. Since January 2006 we have operated a three-element network of identical infrasound pressure transducers, to track explosive eruptions, triangulate source locations of the eruptions, and distinguish activity from several vents with diverse activities. In December 2006 the network was expanded to six identical pressure transducers with improved azimuthal distribution sited ~300 m to 700 m from the erupting vents. These sensors have a dynamic range of +/-125 Pa and are able to record non-distorted waveforms for almost all eruptive events. Since January 2006, eruptions have been identified from locations within the ~40 m diameter phonolitic lava lake, an adjacent smaller "active vent", and a vent ~80 m distant from the lava lake known as "Werner's". Since late 2005 until the end of 2006, activity was considerably elevated at the "lava lake", from which frequent (up to six per day) explosions were noted. These events entailed gas bubble bursts, some of which were capable of ejecting bombs more than 1 km distant and producing infrasonic transients in excess of 100 Pa at a distance of 700 m. Activity from "Werner's" vent was much more subdued in terms of eruptive frequency and the radiated acoustic energy, with all signals less than about 5 Pa at 700 m. Activity from the "active vent" was also observed, though notably, these acoustic transients were extended in duration in terms of time (> 5 s to more than 30 s), which reflects extended duration ash-venting source mechanisms, corroborated by video records. The updated infrasound network has operated through a relative lull in eruptive intensity (November - December 2006 - January 2007). Since January 2007 more frequent and larger explosions from the lava lake have been observed and recorded with infrasound and video. We quantify this recent upsurge in lava lake

EVALUATION OF SOIL VENTING APPLICATION

EPA Science Inventory

The ability of soil venting to inexpensively remove large amounts of volatile organic compounds (VOCs) from contaminated soils is well established. However, the time required using venting to remediate soils to low contaminant levels often required by state and federal regulators...

Diverse styles of submarine venting on the ultraslow spreading Mid-Cayman Rise

PubMed Central

German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M. V.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J. M.; de Lépinay, B. Mercier; Nakamura, K.; Seewald, J. S.; Smith, J. L.; Sylva, S. P.; Van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

2010-01-01

Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global mid-ocean ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultraslow spreading ridges that were the last to be demonstrated to host high-temperature venting but may host systems particularly relevant to prebiotic chemistry and the origins of life. Here we report evidence for previously unknown, diverse, and very deep hydrothermal vents along the ∼110 km long, ultraslow spreading Mid-Cayman Rise (MCR). Our data indicate that the MCR hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultramafic systems and, at ∼5,000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent types identified here and their relative geographic isolation make the MCR unique in the oceans. These new sites offer prospects for an expanded range of vent-fluid compositions, varieties of abiotic organic chemical synthesis and extremophile microorganisms, and unparalleled faunal biodiversity—all in close proximity. PMID:20660317

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

Stereoscopic particle image velocimetry investigations of the mixed convection exchange flow through a horizontal vent

NASA Astrophysics Data System (ADS)

Varrall, Kevin; Pretrel, Hugues; Vaux, Samuel; Vauquelin, Olivier

2017-10-01

The exchange flow through a horizontal vent linking two compartments (one above the other) is studied experimentally. This exchange is here governed by both the buoyant natural effect due to the temperature difference of the fluids in both compartments, and the effect of a (forced) mechanical ventilation applied in the lower compartment. Such a configuration leads to uni- or bi-directional flows through the vent. In the experiments, buoyancy is induced in the lower compartment thanks to an electrical resistor. The forced ventilation is applied in exhaust or supply modes and three different values of the vent area. To estimate both velocity fields and flow rates at the vent, measurements are realized at thermal steady state, flush the vent in the upper compartment using stereoscopic particle image velocimetry (SPIV), which is original for this kind of flow. The SPIV measurements allows the area occupied by both upward and downward flows to be determined.

Risk-Free Volcano Observations Using an Unmanned Autonomous Helicopter: seismic observations near the active vent of Sakurajima volcano, Japan

NASA Astrophysics Data System (ADS)

Ohminato, T.; Kaneko, T.; Koyama, T.; Yasuda, A.; Watanabe, A.; Takeo, M.; Honda, Y.; Kajiwara, K.; Kanda, W.; Iguchi, M.; Yanagisawa, T.

2010-12-01

Observations in the vicinity of summit area of active volcanoes are important not only for understanding physical processes in the volcanic conduit but also for eruption prediction and volcanic hazards mitigation. It is, however, challenging to install observation sensors near active vents because of the danger of sudden eruptions. We need safe and efficient ways of installing sensors near the summit of active volcanoes. We have been developing an volcano observation system based on an unmanned autonomous vehicle (UAV) for risk-free volcano observations. Our UAV is an unmanned autonomous helicopter manufactured by Yamaha-Motor Co., Ltd. The UAV is 3.6m long and weighs 84kg with maximum payload of 10kg. The UAV can aviate autonomously along a previously programmed path within a meter accuracy using real-time kinematics differential GPS equipment. The maximum flight time and distance from the operator are 90 minutes and 5km, respectively. We have developed various types of volcano observation techniques adequate for the UAV, such as aeromagnetic survey, taking infrared and visible images from onboard high-resolution cameras, volcanic ash sampling in the vicinity of active vents. Recently, we have developed an earthquake observation module (EOM), which is exclusively designed for the UAV installation in the vicinity of active volcanic vent. In order to meet the various requirements for UAV installation, the EOM is very compact, light-weight (5-6kg), and is solar-powered. It is equipped with GPS for timing, a communication device using cellular-phone network, and triaxial accelerometers. Our first application of the EOM installation using the UAV is one of the most active volcanoes in Japan, Sakurajima volcano. Since 2006, explosive eruptions have been continuing at the reopened Showa crater at the eastern flank near the summit of Sakurajima. Entering the area within 2 km from the active craters is prohibited, and thus there were no observation station in the vicinity

40 CFR 65.62 - Process vent group determination.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 16 2012-07-01 2012-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a) Group status. The owner or operator of a process vent shall determine the group status (i.e., Group 1, Group 2A...

40 CFR 65.62 - Process vent group determination.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 16 2014-07-01 2014-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a) Group status. The owner or operator of a process vent shall determine the group status (i.e., Group 1, Group 2A...

40 CFR 65.62 - Process vent group determination.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Process vent group determination. 65... (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Process Vents § 65.62 Process vent group determination. (a) Group status. The owner or operator of a process vent shall determine the group status (i.e., Group 1, Group 2A...

40Ar/39Ar dating of tuff vents in the Campi Flegrei caldera (southern Italy): Toward a new chronostratigraphic reconstruction of the Holocene volcanic activity

USGS Publications Warehouse

Fedele, L.; Insinga, D.D.; Calvert, A.T.; Morra, V.; Perrotta, A.; Scarpati, C.

2011-01-01

The Campi Flegrei hosts numerous monogenetic vents inferred to be younger than the 15 ka Neapolitan Yellow Tuff. Sanidine crystals from the three young Campi Flegrei vents of Fondi di Baia, Bacoli and Nisida were dated using 40Ar/39Ar geochronology. These vents, together with several other young edifices, occur roughly along the inner border of the Campi Flegrei caldera, suggesting that the volcanic conduits are controlled by caldera-bounding faults. Plateau ages of ∼9.6 ka (Fondi di Baia), ∼8.6 ka (Bacoli) and ∼3.9 ka (Nisida) indicate eruptive activity during intervals previously interpreted as quiescent. A critical revision, involving calendar age correction of literature 14C data and available 40Ar/39Ar age data, is presented. A new reference chronostratigraphic framework for Holocene Phlegrean activity, which significantly differs from the previously adopted ones, is proposed. This has important implications for understanding the Campi Flegrei eruptive history and, ultimately, for the evaluation of related volcanic risk and hazard, for which the inferred history of its recent activity is generally taken into account.

40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

Code of Federal Regulations, 2011 CFR

2011-07-01

... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer... (d)(3) of this section. (1) Engineering assessment may be used to determine vent stream flow rate...

40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

Code of Federal Regulations, 2013 CFR

2013-07-01

... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer... (d)(3) of this section. (1) Engineering assessment may be used to determine vent stream flow rate...

40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

Code of Federal Regulations, 2014 CFR

2014-07-01

... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer... (d)(3) of this section. (1) Engineering assessment may be used to determine vent stream flow rate...

40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

Code of Federal Regulations, 2012 CFR

2012-07-01

... accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or... From the Synthetic Organic Chemical Manufacturing Industry for Process Vents, Storage Vessels, Transfer... (d)(3) of this section. (1) Engineering assessment may be used to determine vent stream flow rate...

Morphology of cone-fields in SW Elysium Planitia - Traces of hydrothermal venting on Mars?

NASA Astrophysics Data System (ADS)

Lanz, J. K.; Saric, M. B.

2008-09-01

Introduction Small cone-shaped features with summit pits can be found in several regions on Mars; mainly in Isidis Planitia; Elysium Planitia; Amazonis Planitia; Acidalia Planitia; in the Cydonia Region; in Cerberus Planum; the Phlegra Montes and on several volcanic flanks. They vary greatly in size and morphology and have been compared to terrestrial features of various origins; namely (1) cinder cones (e.g. [1]), (2) tuff cones or tuff rings (e.g. [2]), (3) rootless cones (pseudocraters) (e.g. [3], [4]), (4) pingos (e.g. [5], [6]) and (5) mud volcanoes (e.g. [7]). They are often found near volcanic centers and large lava fields or cluster in regions where the volatile content of the Martian regolith was/is supposedly high. This has led to the assumption that (ground-) water or ground ice was a trigger or driving force of cone formation. They could therefore, be an important indicator of the history of water on the planet. We have studied an area in western Elysium Planitia, bordering the Aeolis Planum plateau, which exhibits a large number of pitted cones, ridges and dome-like structures. Their distribution and morphology differs strongly from pitted cones elsewhere in Elysium Planitia, which have mainly been interpreted as hydrovolcanic rootless cones, and from other regions on Mars. Based on our observations, we present an alternative model for cone formation in the study area that might hint towards hydrothermal processes in the Aeolis Planum region and possibly young igneous activity. Aeolis Planum Cones The Aeolis Planum pitted cones (referred to as APCs from now on) cluster along the southern edges of the broad shallow valley that borders the Aeolis Planum Formation (APF) to the north. Cones along the northern edges of the valley are rare and can only be found in association with APF remnants where they strongly resemble the cones in the south. Along the southern border the cone coverage is almost continuous, describing a narrow band approximately 2 to 3 km

Dynamics of hydrocarbon vents: Focus on primary porosity

NASA Astrophysics Data System (ADS)

Johansen, C.; Shedd, W.; Abichou, T.; Pineda-Garcia, O.; Silva, M.; MacDonald, I. R.

2012-12-01

This study investigated the dynamics of hydrocarbon release by monitoring activity of a single vent at a 1215m deep site in the Gulf of Mexico (GC600). An autonomous camera, deployed by the submersible ALVIN, was programmed to capture a close-up image every 4 seconds for approximately 3.5 hours. The images provided the ability to study the gas hydrate outcrop site (that measured 5.2x16.3cm3) in an undisturbed state. The outcrop included an array of 38 tube-like vents through which dark brown oil bubbles are released at a rate ranging from 8 bubbles per minute to 0 bubbles per minute. The average release of bubbles from all the separate vents was 59.5 bubbles per minute, equating the total volume released to 106.38cm per minute. The rate of bubble release decreased toward the end of the observation interval, which coincided approximately with the tidal minimum. Ice worms (Hesiocaeca methanicola, Desbruyères & Toulmond, 1998) were abundant at the vent site. The image sequence showed the ice-worms actively moving in and out of burrows in the mound. It has been speculated that Hesiocaeca methanicola contribute to gas hydrate decomposition by creating burrows and depressions in the gas hydrate matrix (Fisher et al, 2000). Ice worm burrows could generate pathways for the passage of oil and gas through the gas hydrate mound. Gas hydrates commonly occur along active and/or passive continental margins (Kennicutt et al, 1988a). The release of oil and gas at this particular hydrocarbon seep site is along a passive continental margin, and controlled primarily by active salt tectonics as opposed to the movement of continental tectonic plates (Salvador, 1987). We propose a descriptive model governing the release of gas and oil from deep sub-bottom reservoirs at depths of 3000-5000m (MacDonald, 1998), through consolidated and unconsolidated sediments, and finally through gas hydrate deposits at the sea floor. The oil and gas escape from the source rock and/or reservoir through

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.

Explosive volcanism on Mercury: Analysis of vent and deposit morphology and modes of eruption

NASA Astrophysics Data System (ADS)

Jozwiak, Lauren M.; Head, James W.; Wilson, Lionel

2018-03-01

The MESSENGER mission revealed, for the first time, conclusive evidence of explosive volcanism on Mercury. Several previous works have cataloged the appearance and location of explosive volcanism on the planet using a variety of identifying characteristics, including vent presence and deposit color as seen in multispectral image mosaics. We present here a comprehensive catalog of vents of likely volcanic origin; our classification scheme emphasizes vent morphology. We have analyzed the morphologies of all vents in our catalog, and recognize three main morphologies: "simple vent", "pit vent", and "vent-with-mound". The majority of vents we identify are located within impact craters. The spatial distribution of vents does not correlate with the locations of volcanic smooth plains deposits, in contrast to the Moon, nor do vents correlate with the locations of large impact basins (except for the Caloris and Tolstoj basins). Using the degradation state of the vent host crater as a proxy for maximum age, we suggest that vent formation has been active through the Mansurian and into the Kuiperian periods, although the majority of vents were likely formed much earlier in mercurian history. The morphologies and locations of vents are used to investigate a set of plausible formation geometries. We find that the most likely and most prevalent formation geometry is that of a dike, stalled at depth, which then explosively vents to the surface. We compare the vent and deposit size of mercurian pyroclastic deposits with localized and regional lunar pyroclastic deposits, and find a range of possible eruption energies and corresponding variations in eruption style. Localized lunar pyroclastic deposits and the majority of mercurian pyroclastic deposits show evidence for eruption that is consistent with the magmatic foam at the top of a dike reaching a critical gas volume fraction. A subset of mercurian vents, including the prominent Copland-Rachmaninoff vent to the northeast of the

Iron-Oxidizing Bacteria Found at Slow-Spreading Ridge: a Case Study of Capelinhos Hydrothermal Vent (Lucky Strike, MAR 37°N)

NASA Astrophysics Data System (ADS)

Henri, P. A.; Rommevaux, C.; Lesongeur, F.; Emerson, D.; Leleu, T.; Chavagnac, V.

2015-12-01

Iron-oxidizing bacteria becomes increasingly described in different geological settings from volcanically active seamounts, coastal waters, to diffuse hydrothermal vents near seafloor spreading centers [Emerson et al., 2010]. They have been mostly identified and described in Pacific Ocean, and have been only recently found in hydrothermal systems associated to slow spreading center of the Mid-Atlantic Ridge (MAR) [Scott et al., 2015]. During the MoMARSAT'13 cruise at Lucky Strike hydrothermal field (MAR), a new hydrothermal site was discovered at about 1.5 km eastward from the lava lake and from the main hydrothermal vents. This active venting site, named Capelinhos, is therefore the most distant from the volcano, features many chimneys, both focused and diffuses. The hydrothermal end-member fluids from Capelinhos are different from those of the other sites of Lucky Strike, showing the highest content of iron (Fe/Mn≈3.96) and the lowest chlorinity (270 mmol/l) [Leleu et al., 2015]. Most of the chimneys exhibit rust-color surfaces and bacterial mats near diffuse flows. During the MoMARSAT'15 cruise, an active chimney, a small inactive one, and rust-color bacterial mat near diffuse flow were sampled at Capelinhos. Observations by SEM of the hydrothermal samples revealed the presence of iron oxides in an assemblage of tubular "sheaths", assembled "stalks", helical "stalks" and amorphous aggregates. These features are similar to those described from the Loihi iron-mats deposits and argue for the occurrence of iron-oxidizing bacteria. Cultures under micro-aerobic and neutral pH conditions allowed us to isolate strains from the small inactive chimney. Pyrosequencing of the 16S rRNA gene of the isolates and environmental samples will soon be performed, which should confirm the presence of iron-oxidizing bacteria and reveal the organization of bacterial communities in this original and newly discovered hydrothermal site of the slow spreading Mid-Atlantic Ridge. Emerson

PRex: An Experiment to Investigate Detection of Near-field Particulate Deposition from a Simulated Underground Nuclear Weapons Test Vent

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

Keillor, Martin E.; Arrigo, Leah M.; Baciak, James E.

2016-01-01

An experiment to release radioactive particles representative of small-scale venting from an underground nuclear test was conducted to gather data in support of treaty capability development activities. For this experiment, a CO2-driven “air cannon” was used to release lanthanum-140 at ambient temperatures. The radioisotope 140La was chosen as a representative fission fragment with a short half-life and prominent gamma-ray emissions; the choice was also influenced by the successful production and use of 140La with low levels of radioactive contaminants in the Defence Research and Development Canada Field Trials. The source was created through activation of high-purity lanthanum oxide at themore » TRIGA research reactor of Washington State University, Pullman, Washington. Witness plates and air samplers were laid out in an irregular grid covering the area for which the plume was anticipated to deposit based on climatological wind records. A vehicle-mounted spectrometer, and handheld and backpack instruments ranging from polyvinyl toluene to high purity germanium, were used to survey the plume. Additionally, three soil sampling techniques were investigated. The relative sensitivity and utility of sampling and survey methods are discussed in the context of On-Site Inspection.« less

Discovery of abundant hydrothermal venting on the ultraslow-spreading Gakkel ridge in the Arctic Ocean.

PubMed

Edmonds, H N; Michael, P J; Baker, E T; Connelly, D P; Snow, J E; Langmuir, C H; Dick, H J B; Mühe, R; German, C R; Graham, D W

2003-01-16

Submarine hydrothermal venting along mid-ocean ridges is an important contributor to ridge thermal structure, and the global distribution of such vents has implications for heat and mass fluxes from the Earth's crust and mantle and for the biogeography of vent-endemic organisms. Previous studies have predicted that the incidence of hydrothermal venting would be extremely low on ultraslow-spreading ridges (ridges with full spreading rates <2 cm x yr(-1)-which make up 25 per cent of the global ridge length), and that such vent systems would be hosted in ultramafic in addition to volcanic rocks. Here we present evidence for active hydrothermal venting on the Gakkel ridge, which is the slowest spreading (0.6-1.3 cm x yr(-1)) and least explored mid-ocean ridge. On the basis of water column profiles of light scattering, temperature and manganese concentration along 1,100 km of the rift valley, we identify hydrothermal plumes dispersing from at least nine to twelve discrete vent sites. Our discovery of such abundant venting, and its apparent localization near volcanic centres, requires a reassessment of the geologic conditions that control hydrothermal circulation on ultraslow-spreading ridges.

Dynamics of an open basaltic magma system: The 2008 activity of the Halema‘uma‘u Overlook vent, Kīlauea Caldera

USGS Publications Warehouse

Eychenne, Julia; Houghton, Bruce F.; Swanson, Don; Carey, Rebecca; Swavely, Lauren

2015-01-01

On March 19, 2008 a small explosive event accompanied the opening of a 35-m-wide vent (Overlook vent) on the southeast wall of Halema‘uma‘u Crater in Kīlauea Caldera, initiating an eruptive period that extends to the time of writing. The peak of activity, in 2008, consisted of alternating background open-system outgassing and spattering punctuated by sudden, short-lived weak explosions, triggered by collapses of the walls of the vent and conduit. Near-daily sampling of the tephra from this open system, along with exceptionally detailed observations, allow us to study the dynamics of the activity during two eruptive sequences in late 2008. Each sequence includes background activity preceding and following one or more explosions in September and October 2008 respectively. Componentry analyses were performed for daily samples to characterise the diversity of the ejecta. Nine categories of pyroclasts were identified in all the samples, including wall-rock fragments. The six categories of juvenile clasts can be grouped in three classes based on vesicularity: (1) poorly, (2) uniformly highly to extremely, and (3) heterogeneously highly vesicular. The wall-rock and juvenile clasts show dissimilar grainsize distributions, reflecting different fragmentation mechanisms. The wall-rock particles formed by failure of the vent and conduit walls above the magma free surface and were then passively entrained in the eruptive plume. The juvenile componentry reveals consistent contrasts in degassing and fragmentation processes before, during and after the explosive events. We infer a crude ‘layering’ developed in the shallow melt, in terms of both rheology and bubble and volatile contents, beneath a convecting free surface during background activity. A tens-of-centimetres thick viscoelastic surface layer was effectively outgassed and relatively cool, while at depths of less than 100 m, the melt remained slightly supersaturated in volatiles and actively vesiculating

A new InterRidge Working Group : Biogeochemical Interactions at Deep-sea Vents

NASA Astrophysics Data System (ADS)

Le Bris, N.; Boetius, A.; Tivey, M. K.; Luther, G. W.; German, C. R.; Wenzhoefer, F.; Charlou, J.; Seyfried, W. E.; Fortin, D.; Ferris, G.; Takai, K.; Baross, J. A.

2004-12-01

A new Working Group on `Biogeochemical Interactions at deep-sea vents' has been created at the initiative of the InterRidge programme. This interdisciplinary group comprises experts in chemistry, geochemistry, biogeochemistry, and microbial ecology addressing questions of biogeochemical interactions in different MOR and BAB environments. The past decade has raised major issues concerning the interactions between biotic and abiotic compartments of deep-sea hydrothermal environments and the role they play in the microbial turnover of C, S, N, Fe, fluxes from the geosphere to hydrosphere, the formation of biominerals, the functioning of vent ecosystems and life in extreme environments, the deep-biosphere, and the origin of life. Recent multidisciplinary studies have provided some new insights to these issues. Results of some of these studies will be presented here. They point out the variability and complexity of geobiological systems at vents in space and time and highlight the need for interactions across the fields of chemistry, geochemistry, biogeochemistry, and microbial ecology of hydrothermal environments. Limitation for advances in these fields include the availability of seafloor observation/experimentation time, and of underwater instrumentation allowing quantitative, in situ measurements of chemical and biological fluxes, as well as physical and chemical sensing and sampling along small scale gradients and repeated observation of study sites. The aim of this new Working Group is to strengthen the scientific exchange among chemists, geochemists, biogeochemists and microbial ecologists to favor collaboration in field studies including intercomparison of methods and planning of integrated experiments. The Biogeochemical Interactions working group will also foster development of underwater instrumentation for in situ biogeochemical measurements and microscale sampling, and promote exchange and collaboration with students and scientists of neighboring

14 CFR 27.975 - Fuel tank vents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fuel tank vents. 27.975 Section 27.975...

14 CFR 27.975 - Fuel tank vents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Fuel tank vents. 27.975 Section 27.975...

14 CFR 27.975 - Fuel tank vents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Fuel tank vents. 27.975 Section 27.975...

14 CFR 27.975 - Fuel tank vents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Fuel tank vents. 27.975 Section 27.975...

14 CFR 27.975 - Fuel tank vents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: NORMAL CATEGORY ROTORCRAFT Powerplant Fuel System § 27.975 Fuel tank vents. (a) Each fuel tank... system must be designed to minimize spillage of fuel through the vents to an ignition source in the event... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Fuel tank vents. 27.975 Section 27.975...

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…

Mud volcano venting induced gas hydrate formation at the upper slope accretionary wedge, offshore SW Taiwan

NASA Astrophysics Data System (ADS)

Lin, Saulwood; Tseng, Yi-Ting; Cheng, Wan-Yen; Chou, Cheng-Tien; Chen, NeiChen; Hsieh, I.-Chih

2016-04-01

TsanYao Mud Volcano (TYMV) is the largest mud volcano cone in the Hengchun Mud Volcano Group (HCMVG), located at the upper slope of the accrretionary wedge, southwest of Taiwan. The region is under active tectonic activity with the Philippine Plate, moving northwestward at a rate of ~8 cm/year. This region also receives huge quantity of suspended particle load of ~100 mT/year at present time from adjacent small rivers of the Island of Taiwan. Large loads of suspended sediments influx become a major source of organic carbon and later gas and other hydrocarbon. Gas and fluid in the mud volcano are actively venting from deep to the sea floor on the upper slope of the accretionary wedge. In order to understand venting on the HCMVG, echo sounder, towcam and coring were carried out. Pore water sulfate, chloride, potassium, calcium, stable isotope O-18, gas compositions, dissolved sulfide were analysed. The HCMVG consists of 12 volcano cones of different sizes. Large quantity of gas and fluid are venting directly from deep to the TYMV structure high, as well as 50+ other vents as appeared as flares on the echo sounder. Some flares are reaching to the atmosphere and likely a source of green house gases to the atmosphere. Venting fluids include gas bubbles, suspended particle, mud, and breccia. Breccia size could reach more than 12 cm in diameter. Circular bands in different color appeared around the cone may represent stages of vent eruptions. Compositions of vent gas include methane, ethane and propane. High proportions of ethane and propane in the vent gas demonstrated that source of gas are thermogenic in origin. Patchy authigenic carbonate, bacterial mats, bivalves, tube worms and other chemosynthesis organisms were supported by venting gas AOM process near the sea floor. Pore water chloride concentrations show distinct variation pattern from center cone to the side of the volcano, with low in the center and high away from the cone. Pore water with higher than seawater

Near-vent chemical processes in a hydrothermal plume: Insights from an integrated study of the Endeavour segment

NASA Astrophysics Data System (ADS)

Coogan, L. A.; Attar, A.; Mihaly, S. F.; Jeffries, M.; Pope, M.

2017-04-01

The Endeavour segment of the Juan de Fuca mid-ocean ridge is one of the best studied ridge segments and has recently been instrumented as part of Ocean Networks Canada's NEPTUNE cabled observatory. Here we investigate the interaction between high-temperature vent fluids and the overlying water column. A new tow-yo survey found that the average temperature anomaly in the neutrally buoyant plume was ˜0.043°C. The water column temperature and light attenuation anomalies correlate linearly in some areas of the plume but in other areas there is a low light attenuation anomaly relative to the temperature anomaly. This temperature excess is interpreted to reflect heat input through (particle-poor) diffuse flow. If this is correct, about half of the heat flux along the Endeavour segment comes from diffuse flow. Sediment trap and push core data show that the mass accumulation rate of the hydrothermal component of the sediments decreases rapidly with distance from the major vent fields. Large changes in the composition of the hydrothermal component of the sediments also occur with distance from the vent fields. The composition of the sediments indicates (i) sulfides precipitate early and accumulate most rapidly close to the vents with a preferential order of element removal from the plume of Cd > Ag > Cu > Co ˜ Fe; (ii) barite is deposited somewhat further from the vents. Strontium and Pb appear to be strongly incorporated in barite and/or other sulfate minerals; (iii) at most a few percent of the mass of these "insoluble" elements that is vented gets deposited within 1.5 km of the vents.

Hydrogen-limited growth of hyperthermophilic methanogens at deep-sea hydrothermal vents.

PubMed

Ver Eecke, Helene C; Butterfield, David A; Huber, Julie A; Lilley, Marvin D; Olson, Eric J; Roe, Kevin K; Evans, Leigh J; Merkel, Alexandr Y; Cantin, Holly V; Holden, James F

2012-08-21

Microbial productivity at hydrothermal vents is among the highest found anywhere in the deep ocean, but constraints on microbial growth and metabolism at vents are lacking. We used a combination of cultivation, molecular, and geochemical tools to verify pure culture H(2) threshold measurements for hyperthermophilic methanogenesis in low-temperature hydrothermal fluids from Axial Volcano and Endeavour Segment in the northeastern Pacific Ocean. Two Methanocaldococcus strains from Axial and Methanocaldococcus jannaschii showed similar Monod growth kinetics when grown in a bioreactor at varying H(2) concentrations. Their H(2) half-saturation value was 66 μM, and growth ceased below 17-23 μM H(2), 10-fold lower than previously predicted. By comparison, measured H(2) and CH(4) concentrations in fluids suggest that there was generally sufficient H(2) for Methanocaldococcus growth at Axial but not at Endeavour. Fluids from one vent at Axial (Marker 113) had anomalously high CH(4) concentrations and contained various thermal classes of methanogens based on cultivation and mcrA/mrtA analyses. At Endeavour, methanogens were largely undetectable in fluid samples based on cultivation and molecular screens, although abundances of hyperthermophilic heterotrophs were relatively high. Where present, Methanocaldococcus genes were the predominant mcrA/mrtA sequences recovered and comprised ∼0.2-6% of the total archaeal community. Field and coculture data suggest that H(2) limitation may be partly ameliorated by H(2) syntrophy with hyperthermophilic heterotrophs. These data support our estimated H(2) threshold for hyperthermophilic methanogenesis at vents and highlight the need for coupled laboratory and field measurements to constrain microbial distribution and biogeochemical impacts in the deep sea.

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 24 Housing and Urban Development 5 2010-04-01 2010-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 5 2014-04-01 2014-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 24 Housing and Urban Development 5 2012-04-01 2012-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

24 CFR 3280.710 - Venting, ventilation and combustion air.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 5 2013-04-01 2013-04-01 false Venting, ventilation and combustion... Fuel Burning Systems § 3280.710 Venting, ventilation and combustion air. (a) The venting as required by... appliance listing and the appliance manufacturer's instructions. (b) Venting and combustion air systems...

Origin of Magnetic High at Basalt-Ultramafic Hosted Hydrothermal Vent Field in the Central Indian Ridge

NASA Astrophysics Data System (ADS)

Fujii, M.; Okino, K.; Sato, T.; Sato, H.; Nakamura, K.

2014-12-01

Hydrothermal alteration processes can change crustal magnetization by destruction and creation of magnetic minerals. In the Yokoniwa hydrothermal vent field (YHVF), located at the NTO-massif in the Central Indian Ridge, a high magnetization zone (with ~12 A/m in ~200 m-scale) was discovered by previous deepsea AUV survey. Basalts and ultramafic rocks were found around the YHVF, however the origin of magnetic high and its relationship with hydrothermal activity are remains to be investigated. Therefore, we conducted additional magnetic field measurement, rock sampling, and geological observation using submersible Shinkai 6500 during the YK09-13 and YK13-03 cruises. Vector geomagnetic field were obtained along the dive tracks at an altitude of ~ 10 m. The crustal absolute magnetization is estimated using the 2D and 3D forward modeling technique. The values of magnetization show ~10 A/m just around the YHVF. This value is consistent with that of equivalent magnetization deduced from AUV data. Rock magnetic characters were measured for 8 basalts, 4 dolerites, 5 sulfides, and 30 serpentinized peridotites (SPs). The measurements of NRM, magnetic susceptibility, magnetic hysteresis, low (6-300K) and high (50-700°C) temperature magnetization curves were performed. The estimated magnetization values are 0.1-6 A/m in basalts, 0.2-0.6 A/m in dolerites, and <0.1 A/m in sulfides. The SPs show strong magnetization of 0.4-11 A/m. The magnetic grain sizes ranges over single domain to pseudo-single domain. The temperature-magnetization curves clearly show the Verway transition and Currie temperature of 580 °C, therefore magnetic carrier of SPs is supposed as pure magnetite, which is created during serpentinization process. Serpentinization degree (Sd) was also estimated by grain density measurement based on empirical formula from Oufi et al., 2002. Amount of magnetite was also estimated from saturation magnetization. The results show that the values of Sd vary in a range from 17

Spacecraft compartment venting

NASA Astrophysics Data System (ADS)

Scialdone, John J.

1998-10-01

At various times, concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

Spacecraft Compartment Venting

NASA Technical Reports Server (NTRS)

Scialdone, John J.

1998-01-01

At various time concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

Performance of a passively vented field-scale biofilter for the microbial oxidation of landfill methane.

PubMed

Gebert, J; Gröngröft, A

2006-01-01

An upflow biofilter system was operated on a passively vented landfill for the treatment of residual landfill methane. Biofilter methane emissions as a basis for determining methane removal rates were assessed by manual and automated chamber measurements, by measuring methane concentrations in the top layer gaseous phase in combination with gas flow rates, and by evaluating the methane load in the reverse gas flow following the change of landfill gas flux direction as governed by the course of barometric pressure. Methane removal rates were very high with maximum values of 80 g h(-1) m(-3). For the observed cases, the limit of biofilter methane oxidation capacity was not reached and absolute removal rates were thus linearly correlated to the amount of methane entering the filter. The analysis of methane loads flowing back from the biofilter following phases of longer, continuous and non-oscillating landfill gas emission, however, revealed that in these situations biofilter performance is restricted by deficient oxygen supply. At the oxygen-restricted capacity limit, removal rates are influenced by temperature (positively), methane influx (negatively) and flow rate (negatively) as a measure for the displacement of oxygen. These situations, however, account for only 12% of all emission phases. The investigated biofilter capacity, as derived from laboratory analyses of methanotrophic activities, is sufficient to oxidise 62% of the methane load emitted annually. Field and laboratory data provide a stable basis for the dimensioning of filters in future applications.

Video monitoring reveals pulsating vents and propagation path of fissure eruption during the March 2011 Pu'u 'Ō'ō eruption, Kilauea volcano

NASA Astrophysics Data System (ADS)

Witt, Tanja; Walter, Thomas R.

2017-01-01

Lava fountains are a common eruptive feature of basaltic volcanoes. Many lava fountains result from fissure eruptions and are associated with the alignment of active vents and rising gas bubbles in the conduit. Visual reports suggest that lava fountain pulses may occur in chorus at adjacent vents. The mechanisms behind such a chorus of lava fountains and the underlying processes are, however, not fully understood. The March 2011 eruption at Pu'u 'Ō'ō (Kilauea volcano) was an exceptional fissure eruption that was well monitored and could be closely approached by field geologists. The fissure eruption occurred along groups of individual vents aligned above the feeding dyke. We investigate video data acquired during the early stages of the eruption to measure the height, width and velocity of the ejecta leaving eight vents. Using a Sobel edge-detection algorithm, the activity level of the lava fountains at the vents was determined, revealing a similarity in the eruption height and frequency. Based on this lava fountain time series, we estimate the direction and degree of correlation between the different vents. We find that the height and velocity of the eruptions display a small but systematic shift in time along the vents, indicating a lateral migration of lava fountaining at a rate of 11 m/s from W to E. This finding is in agreement with a propagation model of a pressure wave originating at the Kilauea volcano and propagating through the dyke at 10 m/s from W to E. Based on this approach from videos only 30 s long, we are able to obtain indirect constraints on the physical dyke parameters, with important implications for lateral magma flow processes at depth. This work shows that the recording and analysis of video data provide important constraints on the mechanisms of lava fountain pulses. Even though the video sequence is short, it allows for the confirmation of the magma propagation direction and a first-order estimation of the dyke dimensions.

Investigating pyroclast ejection dynamics using shock-tube experiments: temperature, grain size and vent geometry effects.

NASA Astrophysics Data System (ADS)

Cigala, V.; Kueppers, U.; Dingwell, D. B.

2015-12-01

Explosive volcanic eruptions eject large quantities of gas and particles into the atmosphere. The portion directly above the vent commonly shows characteristics of underexpanded jets. Understanding the factors that influence the initial pyroclast ejection dynamics is necessary in order to better assess the resulting near- and far-field hazards. Field observations are often insufficient for the characterization of volcanic explosions due to lack of safe access to such environments. Fortunately, their dynamics can be simulated in the laboratory where experiments are performed under controlled conditions. We ejected loose natural particles from a shock-tube while controlling temperature (25˚ and 500˚C), overpressure (15MPa), starting grain size distribution (1-2 mm, 0.5-1 mm and 0.125-0.250 mm), sample-to-vent distance and vent geometry. For each explosion we quantified the velocity of individual particles, the jet spreading angle and the production of fines. Further, we varied the setup to allow for different sample-to-gas ratios and deployed four different vent geometries: 1) cylindrical, 2) funnel with a flaring of 30˚, 3) funnel with a flaring of 15˚ and 4) nozzle. The results showed maximum particle velocities up to 296 m/s, gas spreading angles varying from 21˚ to 37˚ and particle spreading angles from 3˚ to 40˚. Moreover we observed dynamically evolving ejection characteristics and variations in the production of fines during the course of individual experiments. Our experiments mechanistically mimic the process of pyroclast ejection. Thus the capability for constraining the effects of input parameters (fragmentation conditions) and conduit/vent geometry on ballistic pyroclastic plumes has been clearly established. These data obtained in the presence of well-documented conduit and vent conditions, should greatly enhance our ability to numerically model explosive ejecta in nature.

Implications of historical eruptive-vent migration on the northeast rift zone of Mauna Loa Volcano, Hawaii

NASA Astrophysics Data System (ADS)

Lockwood, John P.

1990-07-01

Five times within the past 138 yr (1852, 1855-1856, 1880-1881, 1942, and 1984), lava flows from vents on the northeast rift zone of Mauna Loa Volcano have reached within a few kilometres of Hilo (the largest city on the Island of Hawaii). Most lavas erupted on this rift zone in historical time have traveled northeastward (toward Hilo), because their eruptive vents have been concentrated north of the rift zone's broad topographic axis. However, with few exceptions each successive historical eruption on the northeast rift zone has occurred farther southeast than the preceding one. Had the 1984 eruptive vents (the most southeasterly yet) opened less than 200 m farther southeast, the bulk of the 1984 lavas would have flowed away from Hilo. If this historical vent-migration pattern continues, the next eruption on the northeast rift zone could send lavas to the southeast, toward less populated areas. The historical Mauna Loa vent-migration patterns mimic the southeastern "younging" of the Hawaiian-Emperor volcanic chain and may be cryptically related to northwestward movement of the Pacific plate. Systematic temporal-spatial vent-migration patterns may characterize eruptive activity at other volcanoes with flank activity and should be considered as an aid to long-term prediction of eruption sites.

Deep-sea vent chemoautotrophs: diversity, biochemistry and ecological significance.

PubMed

Nakagawa, Satoshi; Takai, Ken

2008-07-01

Deep-sea vents support productive ecosystems driven primarily by chemoautotrophs. Chemoautotrophs are organisms that are able to fix inorganic carbon using a chemical energy obtained through the oxidation of reduced compounds. Following the discovery of deep-sea vent ecosystems in 1977, there has been an increasing knowledge that deep-sea vent chemoautotrophs display remarkable physiological and phylogenetic diversity. Cultivation-dependent and -independent studies have led to an emerging view that the majority of deep-sea vent chemoautotrophs have the ability to derive energy from a variety of redox couples other than the conventional sulfur-oxygen couple, and fix inorganic carbon via the reductive tricarboxylic acid cycle. In addition, recent genomic, metagenomic and postgenomic studies have considerably accelerated the comprehensive understanding of molecular mechanisms of deep-sea vent chemoautotrophy, even in yet uncultivable endosymbionts of vent fauna. Genomic analysis also suggested that there are previously unrecognized evolutionary links between deep-sea vent chemoautotrophs and important human/animal pathogens. This review summarizes chemoautotrophy in deep-sea vents, highlighting recent biochemical and genomic discoveries.

Hydrothermal vents and methane seeps: Rethinking the sphere of influence

USGS Publications Warehouse

Levin, Lisa A.; Baco, Amy; Bowden, David; Colaco, Ana; Cordes, Erik E.; Cunha, Marina; Demopoulos, Amanda W.J.; Gobin, Judith; Grupe, Ben; Le, Jennifer; Metaxas, Anna; Netburn, Amanda; Rouse, Greg; Thurber, Andrew; Tunnicliffe, Verena; Van Dover, Cindy L.; Vanreusel, Ann; Watling, Les

2016-01-01

Although initially viewed as oases within a barren deep ocean, hydrothermal vent and methane seep communities are now recognized to interact with surrounding ecosystems on the sea floor and in the water column, and to affect global geochemical cycles. The importance of understanding these interactions is growing as the potential rises for disturbance from oil and gas extraction, seabed mining and bottom trawling. Here we synthesize current knowledge of the nature, extent and time and space scales of vent and seep interactions with background systems. We document an expanded footprint beyond the site of local venting or seepage with respect to elemental cycling and energy flux, habitat use, trophic interactions, and connectivity. Heat and energy are released, global biogeochemical and elemental cycles are modified, and particulates are transported widely in plumes. Hard and biotic substrates produced at vents and seeps are used by “benthic background” fauna for attachment substrata, shelter, and access to food via grazing or through position in the current, while particulates and fluid fluxes modify planktonic microbial communities. Chemosynthetic production provides nutrition to a host of benthic and planktonic heterotrophic background species through multiple horizontal and vertical transfer pathways assisted by flow, gamete release, animal movements, and succession, but these pathways remain poorly known. Shared species, genera and families indicate that ecological and evolutionary connectivity exists among vents, seeps, organic falls and background communities in the deep sea; the genetic linkages with inactive vents and seeps and background assemblages however, are practically unstudied. The waning of venting or seepage activity generates major transitions in space and time that create links to surrounding ecosystems, often with identifiable ecotones or successional stages. The nature of all these interactions is dependent on water depth, as well as

Molecular Diversity and Activity of Methanogens in the Subseafloor at Deep-Sea Hydrothermal Vents of the Pacific Ocean (Invited)

NASA Astrophysics Data System (ADS)

Huber, J. A.; Merkel, A.; Holden, J. F.; Lilley, M. D.; Butterfield, D. A.

2009-12-01

Methanogenesis is thought to represent one of the most ancient metabolic pathways on Earth, and methanogens may serve as important primary producers in warm crustal habitats at deep-sea hydrothermal vents. Many of these obligate chemolithoautotrophs depend solely on geochemically-derived energy and carbon sources and grow at high temperatures under strictly anaerobic conditions. A combined geochemical and microbiological approach was used to determine the distribution and molecular diversity of methanogens in low temperature diffuse vent fluids from the Endeavour Segment R2K ISS site, as well as Axial Seamount and volcanoes of the Mariana Arc. Geochemical data from hot and adjacent warm diffuse vent fluids provided chemical indicators to guide sample selection for detailed polymerase chain reaction (PCR)-based analysis of the key enzyme for methane formation, methyl-coenzyme M reductase (mcrA), as well as archaeal 16S rRNA genes. At most Endeavour vent sites, hydrogen concentrations were too low to support hydrogenotrophic methanogensis directly and only one diffuse site, Easter Island, had a positive signal for the mcrA gene. These sequences were most closely related to members of the order Methanococcales, as well as anaerobic methane oxidizers (ANME-1). The presence of ANME, which are rarely found in non-sedimented marine environments, is another line of evidence supporting the occurrence of buried sediments at Endeavour. At Axial, a number of diffuse vents have strong chemical indicators of methanogenesis. Methanogenic communities were detected at 3 sites on the southeast side of the caldera: the northern end of the 1998 lava flow, the International District, and on the pre-1987 lava flow. Time series work at Marker 113 showed that in 4 different years over the last 6 years methanogenic communities are active and abundant, suggesting a stable anaerobic, warm subseafloor habitat. Results show that members of the order Methanococcales dominate at this site

Degassing during magma ascent in the Mule Creek vent (USA)

NASA Astrophysics Data System (ADS)

Stasiuk, Mark V.; Barclay, Jenni; Carroll, Michael R.; Jaupart, Claude; Ratté, James C.; Sparks, R. Stephen J.; Tait, Stephen R.

1996-09-01

The structures and textures of the rhyolite in the Mule Creek vent (New Mexico, USA) indicate mechanisms by which volatiles escape from silicic magma during eruption. The vent outcrop is a 300-m-high canyon wall comprising a section through the top of a feeder conduit, vent and the base of an extrusive lava dome. Field relations show that eruption began with an explosive phase and ended with lava extrusion. Analyses of glass inclusions in quartz phenocrysts from the lava indicate that the magma had a pre-eruptive dissolved water content of 2.5 3.0 wt% and, during eruption, the magma would have been water-saturated over the vertical extent of the present outcrop. However, the vesicularity of the rhyolite is substantially lower than that predicted from closed-system models of vesiculation under equilibrium conditions. At a given elevation in the vent, the volume fraction of primary vesicles in the rhyolite increases from zero close to the vent margin to values of 20 40 vol.% in the central part. In the centre the vesicularity increases upward from approximately 20 vol.% at 300 m below the canyon rim to approximately 40 vol.% at 200 m, above which it shows little increase. To account for the discrepancy between observed vesicularity and measured water content, we conclude that gas escaped during ascent, probably beginning at depths greater than exposed, by flow through the vesicular magma. Gas escape was most efficient near the vent margin, and we postulate that this is due both to the slow ascent of magma there, giving the most time for gas to escape, and to shear, favouring bubble coalescence. Such shear-related permeability in erupting magma is supported by the preserved distribution of textures and vesicularity in the rhyolite: Vesicles are flattened and overlapping near the dense margins and become progressively more isolated and less deformed toward the porous centre. Local zones have textures which suggest the coalescence of bubbles to form permeable

Degassing during magma ascent in the Mule Creek vent (USA)

USGS Publications Warehouse

Stasiuk, M.V.; Barclay, J.; Carroll, M.R.; Jaupart, Claude; Ratte, J.C.; Sparks, R.S.J.; Tait, S.R.

1996-01-01

The structures and textures of the rhyolite in the Mule Creek vent (New Mexico, USA) indicate mechanisms by which volatiles escape from silicic magma during eruption. The vent outcrop is a 300-m-high canyon wall comprising a section through the top of a feeder conduit, vent and the base of an extrusive lava dome. Field relations show that eruption began with an explosive phase and ended with lava extrusion. Analyses of glass inclusions in quartz phenocrysts from the lava indicate that the magma had a pre-eruptive dissolved water content of 2.5-3.0 wt% and, during eruption, the magma would have been water-saturated over the vertical extent of the present outcrop. However, the vesicularity of the rhyolite is substantially lower than that predicted from closed-system models of vesiculation under equilibrium conditions. At a given elevation in the vent, the volume fraction of primary vesicles in the rhyolite increases from zero close to the vent margin to values of 20-40 vol.% in the central part. In the centre the vesicularity increases upward from approximately 20 vol.% at 300 m below the canyon rim to approximately 40 vol.% at 200 m, above which it shows little increase. To account for the discrepancy between observed vesicularity and measured water content, we conclude that gas escaped during ascent, probably beginning at depths greater than exposed, by flow through the vesicular magma. Gas escape was most efficient near the vent margin, and we postulate that this is due both to the slow ascent of magma there, giving the most time for gas to escape, and to shear, favouring bubble coalescence. Such shear-related permeability in erupting magma is supported by the preserved distribution of textures and vesicularity in the rhyolite: Vesicles are flattened and overlapping near the dense margins and become progressively more isolated and less deformed toward the porous centre. Local zones have textures which suggest the coalescence of bubbles to form permeable

Vented Capacitor

DOEpatents

Brubaker, Michael Allen; Hosking, Terry Alan

2006-04-11

A technique of increasing the corona inception voltage (CIV), and thereby increasing the operating voltage, of film/foil capacitors is described. Intentional venting of the capacitor encapsulation improves the corona inception voltage by allowing internal voids to equilibrate with the ambient environment.

Faunal composition and organic surface encrustations at hydrothermal vents on the southern Juan De Fuca Ridge

NASA Astrophysics Data System (ADS)

Tunnicliffe, Verena; Fontaine, A. R.

1987-10-01

Examination of a small collection of macroinvertebrates from three vents of the southern Juan de Fuca vent field reveals differences between the vents with respect to species composition, species habits, and microbial and metallic deposits on their surfaces. TWo apparently new vestimentiferan species were found, and for the first time the Juan de Fuca palm worm was observed to dwell on smokers. High acidity values recorded in this system may interfere with the process of shell calcification in an archaeogastropod snail. The surfaces of vestimentifer an tubes at two vents are heavily encrusted with microbial and metallic accumulations. Scanning electron microscope, transmission electron microscope, and energy dispersive X ray microanalysis observations show that iron-based crusts on orange tubes are built from accumulations of an Fe-rich particle of distinctive size and shape. Morphological evidence is presented for the microbial origin of Fe-rich particles. Zn-rich particles found on black tubes are not of microbial origin. We suggest that iron deposition on surfaces in the vent environment is initially biocatalytic but subsequent deposits may build by simple inorganic reactions.

PRex: An Experiment to Investigate Detection of Near-field Particulate Deposition from a Simulated Underground Nuclear Weapons Test Vent.

PubMed

Keillor, Martin E; Arrigo, Leah M; Baciak, James E; Chipman, Veraun; Detwiler, Rebecca S; Emer, Dudley F; Kernan, Warnick J; Kirkham, Randy R; MacDougall, Matthew R; Milbrath, Brian D; Rishel, Jeremy P; Seifert, Allen; Seifert, Carolyn E; Smart, John E

2016-05-01

A radioactive particulate release experiment to produce a near-field ground deposition representative of small-scale venting from an underground nuclear test was conducted to gather data in support of treaty capability development activities. For this experiment, a CO2-driven "air cannon" was used to inject (140)La, a radioisotope of lanthanum with 1.7-d half-life and strong gamma-ray emissions, into the lowest levels of the atmosphere at ambient temperatures. Witness plates and air samplers were laid out in an irregular grid covering the area where the plume was anticipated to deposit based on climatological wind records. This experiment was performed at the Nevada National Security Site, where existing infrastructure, radiological procedures, and support personnel facilitated planning and execution of the work. A vehicle-mounted NaI(Tl) spectrometer and a polyvinyl toluene-based backpack instrument were used to survey the deposited plume. Hand-held instruments, including NaI(Tl) and lanthanum bromide scintillators and high purity germanium spectrometers, were used to take in situ measurements. Additionally, three soil sampling techniques were investigated and compared. The relative sensitivity and utility of sampling and survey methods are discussed in the context of on-site inspection.

33 CFR 183.520 - Fuel tank vent systems.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Fuel tank vent systems. 183.520...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.520 Fuel tank vent systems. (a) Each fuel tank must have a vent system that prevents pressure in the tank from exceeding 80...

33 CFR 183.520 - Fuel tank vent systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Fuel tank vent systems. 183.520...) BOATING SAFETY BOATS AND ASSOCIATED EQUIPMENT Fuel Systems Equipment Standards § 183.520 Fuel tank vent systems. (a) Each fuel tank must have a vent system that prevents pressure in the tank from exceeding 80...

Propagation of vent CO2 in a subtropical shallow-water ecosystem assessed by stable carbon isotopes

NASA Astrophysics Data System (ADS)

Cheng, Y. F.; Chen, C. T. A.; Liao, Y. M.; Lin, Y. S.

2016-02-01

Carbon cycle of the ocean plays an important role in the global change associated with the emission of CO2. Anthropogenic CO2 dissolves in seawater, changes carbon chemistry of the ocean, and affects marine life in different and complicated ways. In this study, we investigated stable carbon isotope systematics of a shallow-water hydrothermal field near the Kueishantao Islet off NE Taiwan, which has vent gas composition dominated by CO2 and world record breaking low pH hydrothermal fluids. By studying this natural laboratory of ocean acidification, we aim at clarifying to which extent the high dosage of CO2 propagates in the subtropical shallow-water ecosystem, and how it affects the carbon cycle. Samples of seawater and suspended particles were collected from stations of two nearshore-offshore transects, one with hydrothermal vents at the nearshore end (Transect M, 1230 m long) and the other serving as the baseline (Transect B, 1560 m long). Surface seawater of Transect M showed increasing pH in the offshore direction, from 5.8 at the vent mouths to 7.6 at the most distant station. In contrast, pH of surface water decreased seaward from 8.0 to 7.8 in Transect B. The δ13C values of the vent CO2 averaged -6.4‰, consistent with the range attributed to mantle CO2. Seawater DIC δ13C values of Transect M were 13C-depleted (as negative as -2.5‰) at the vent mouths, and became increasingly 13C-enriched till 0.7‰ at the most distant station. This pattern is in clear contrast to that of Transect B, the DIC δ13C values of which decreased from 0.7 to 0.6 ‰ in the offshore direction. We concluded that the vent CO2 has propagated in the surface ocean at least >700 m away from the hydrothermal field. Our next step is to explore how the vent CO2 affects the stable carbon isotopes of particulate organic matter, and to assess the effect of vent CO2 using quantitative approaches.

Evidence for early life in Earth's oldest hydrothermal vent precipitates.

PubMed

Dodd, Matthew S; Papineau, Dominic; Grenne, Tor; Slack, John F; Rittner, Martin; Pirajno, Franco; O'Neil, Jonathan; Little, Crispin T S

2017-03-01

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite-haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

46 CFR 56.50-85 - Tank-vent piping.

Code of Federal Regulations, 2010 CFR

2010-10-01

... of the tanks to vent pipes. (2) Tanks having a comparatively small surface, such as fuel oil settling... 46 Shipping 2 2010-10-01 2010-10-01 false Tank-vent piping. 56.50-85 Section 56.50-85 Shipping... APPURTENANCES Design Requirements Pertaining to Specific Systems § 56.50-85 Tank-vent piping. (a) This section...

Brucite-carbonate chimneys found at the Shinkai Seep Field, a serpentine-hosted vent system in the Southern Mariana Forearc

NASA Astrophysics Data System (ADS)

Okumura, T.; Ohara, Y.; Stern, R. J.; Yamanaka, T.; Onishi, Y.; Watanabe, H.; Chen, C.; Bloomer, S. H.; Pujana, I.; Sakai, S.; Ishii, T.; Takai, K.

2016-12-01

Brucite-carbonate chimneys have been discovered from the Shinkai Seep Field (SSF) in the southernmost Mariana forearc, on the landward trench slope to the northeast of the Challenger Deep. SSF is the deepest known ( 5700 mbsl) serpentinization-hosted cold seep and associated ecosystem. Explorations of SSF over the past six years led to the discovery of eleven vesicomyid clam colony sites and four chimney sites occurring within an area of 500 square meters. Observations and geochemical analysis reveal three types (I-III) of chimneys, formed by the precipitation and dissolution of constitutive minerals. Type I chimneys are bright white to light yellow, have a spiky crystalline and wrinkled surface with active microbial mats, and are mostly brucite; these formed by rapid precipitation from vent fluid under high fluid flux conditions. Type II chimneys are white to dull brown, show tuberous textures like vascular bundles, and are covered with grayish microbial mats and dense populations of the polychaete Phyllochaetopterus. This type of chimney contains more carbonate than type I chimney because of precipitation under lower fluid flux conditions and re-equilibration with seawater. Type III chimneys are ivory colored with surface depressions and lack living microbial mats or animals. This type of chimney is mostly carbonate and is actively dissolving. Stable carbon isotope compositions of carbonates in the two types (I and II) of active chimneys are extremely enriched in δ13C (up to +24.1‰), likely reflecting microbial consumption of 12C from extremely low concentration of dissolved inorganic carbon in the serpentinization-driven alkaline fluid. The active SSF chimneys are also unique in that they sustain abundant endo- and epi-lithic Phyllochaetopterus populations. The geochemical and geobiological features of the SSF chimney are distinct from those in the Lost City hydrothermal field near Mid-Atlantic Ridge, another serpentinization-driven hydrothermal system. Our

System for venting gas from a liquid storage tank

NASA Astrophysics Data System (ADS)

Dugan, Regina E.

1989-07-01

Gas is vented from a non-cryogenic liquid storage tank while discharging pressurized liquid from a tube into the tank through a plurality of inclined jets, circumferentially spaced about an end of a vent tube positioned within the tube. Each jet is directed toward a central axis of the vent tube, such that the end of the vent tube receives gas from the vessel passing between individual jetstreams, which in combination form a conical shaped barrier to liquid droplets which would otherwise also pass to the vent tube and out the tank. Gas is thus vented through the central tube while pressurized liquid flows in an axially opposite direction in the annulus between the inner vent tube and the outer liquid tube. The system of the present invention is prarticularly well suited for venting gas from a tank being replenished with liquid at a zero or near zero gravity environment. A screen-type liquid acquisition device employing surface tension is provided for withdrawing substantially liquid from the tank. The withdrawn liquid may be resupplied to the liquid tube under pressure supplied by a circulating pump, thereby releasing substantially only gas from the storage tank to reduce the pressure in the tank.

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.

In Situ Materials Study in Hot Hydrothermal Vent Fluid

NASA Astrophysics Data System (ADS)

Holland, P. M.; Schindele, W. J.; Holland, C. E.; Lilley, M. D.; Olson, E. J.

2004-12-01

We are developing methods and technology for in situ sampling and analysis of volatiles from hot hydrothermal vent fluids inside the mixing boundary. These fluids can reach temperatures of up to 400° C and are known to be corrosive to most materials. While titanium has been the material of choice for contact with these fluids, we wanted to assess whether other materials, such as Hastelloy or nickel might be suitable for in situ sampling from hydrothermal vents. For the present study, small (1/16" o.d.) tubes of chemically pure titanium, Hastelloy C, and Nickel 200 were prepared, using 316 stainless steel as a control. These were placed in an assembly with other test items, and inserted into the hydrothermal vent Sully in the Main Endeavor Field on the Juan de Fuca Plate in June 2003 by the Jason II ROV operated from the R/V Thompson. The assembly was retrieved 46 days later after exposure to approximately 360° C hydrothermal vent fluid at a depth of 2200 m. Inspection showed the stainless steel to be completely eroded away and nickel to be extensively corroded, however both the Hastelloy and titanium tubes were in excellent condition with the 0.030" i.d. passages in the tubes remaining open. Other test items included a miniature titanium filtered inlet fitting containing an 80 mesh titanium screen made of 0.004" (0.1 mm) chemically pure titanium wire, an Inconel washer and a sapphire ball. Apart from some discoloration, there appeared to be no significant degradation in these materials apart from signs of etching on the sapphire.

Bathymodiolus growth dynamics in relation to environmental fluctuations in vent habitats

NASA Astrophysics Data System (ADS)

Nedoncelle, K.; Lartaud, F.; Contreira Pereira, L.; Yücel, M.; Thurnherr, A. M.; Mullineaux, L.; Le Bris, N.

2015-12-01

The deep-sea mussel Bathymodiolus thermophilus is a dominant species in the East Pacific Rise (EPR) hydrothermal vent fields. On the EPR volcanically unstable area, this late colonizer reaches high biomass within 4-5 years on new habitats created by lava flows. The environmental conditions and growth rates characterizing the reestablishment of B. thermophilus populations are however largely unknown, leaving unconstrained the role of this foundation species in the ecosystem dynamics. A typical example from the vent field at 9°50'N that was affected by the last massive eruption was the Bio-9 hydrothermal vent site. Here, six years later, a large mussel population had reestablished. The von Bertalanffy growth model estimates the oldest B. thermophilus specimens to be 1.3 year-old in March 2012, consistent with the observation of scarce juveniles among tubeworms in 2010. Younger cohorts were also observed in 2012 but the low number of individuals, relatively to older cohorts, suggests limited survival or growth of new recruits at this site, that could reflect unsuitable habitat conditions. To further explore this asumption, we investigated the relationships between mussel growth dynamics and habitat properties. The approach combined sclerochronology analyses of daily shell growth with continuous habitat monitoring for two mussel assemblages; one from the Bio-9 new settlement and a second from the V-vent site unreached by the lava flow. At both vent sites, semi-diurnal fluctuations of abiotic conditions were recorded using sensors deployed in the mussel bed over 5 to 10 days. These data depict steep transitions from well oxygenated to oxygen-depleted conditions and from alkaline to acidic pH, combined with intermittent sulfide exposure. These semi-diurnal fluctuations exhibited marked changes in amplitude over time, exposing mussels to distinct regimes of abiotic constraints. The V-vent samples allowed growth patterns to be examined at the scale of individual life and

Google Earth locations of USA and seafloor hydrothermal vents with associated rare earth element data

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

Andrew Fowler

Google Earth .kmz files that contain the locations of geothermal wells and thermal springs in the USA, and seafloor hydrothermal vents that have associated rare earth element data. The file does not contain the actual data, the actual data is available through the GDR website in two tier 3 data sets entitled "Compilation of Rare Earth Element Analyses from US Geothermal Fields and Mid Ocean Ridge (MOR) Hydrothermal Vents" and "Rare earth element content of thermal fluids from Surprise Valley, California"

Monitoring arrangement for vented nuclear fuel elements

DOEpatents

Campana, Robert J.

1981-01-01

In a nuclear fuel reactor core, fuel elements are arranged in a closely packed hexagonal configuration, each fuel element having diametrically opposed vents permitting 180.degree. rotation of the fuel elements to counteract bowing. A grid plate engages the fuel elements and forms passages for communicating sets of three, four or six individual vents with respective monitor lines in order to communicate vented radioactive gases from the fuel elements to suitable monitor means in a manner readily permitting detection of leakage in individual fuel elements.

Submarine radial vents on Mauna Loa Volcano, Hawai'i

USGS Publications Warehouse

Wanless, V. Dorsey; Garcia, M.O.; Trusdell, F.A.; Rhodes, J.M.; Norman, M.D.; Weis, Dominique; Fornari, D.J.; Kurz, M.D.; Guillou, Herve

2006-01-01

A 2002 multibeam sonar survey of Mauna Loa's western flank revealed ten submarine radial vents and three submarine lava flows. Only one submarine radial vent was known previously. The ages of these vents are constrained by eyewitness accounts, geologic relationships, Mn-Fe coatings, and geochemical stratigraphy; they range from 128 years B.P. to possibly 47 ka. Eight of the radial vents produced degassed lavas despite eruption in water depths sufficient to inhibit sulfur degassing. These vents formed truncated cones and short lava flows. Two vents produced undegassed lavas that created “irregular” cones and longer lava flows. Compositionally and isotopically, the submarine radial vent lavas are typical of Mauna Loa lavas, except two cones that erupted alkalic lavas. He-Sr isotopes for the radial vent lavas follow Mauna Loa's evolutionary trend. The compositional and isotopic heterogeneity of these lavas indicates most had distinct parental magmas. Bathymetry and acoustic backscatter results, along with photography and sampling during four JASON2 dives, are used to produce a detailed geologic map to evaluate Mauna Loa's submarine geologic history. The new map shows that the 1877 submarine eruption was much larger than previously thought, resulting in a 10% increase for recent volcanism. Furthermore, although alkalic lavas were found at two radial vents, there is no systematic increase in alkalinity among these or other Mauna Loa lavas as expected for a dying volcano. These results refute an interpretation that Mauna Loa's volcanism is waning. The submarine radial vents and flows cover 29 km2 of seafloor and comprise a total volume of ∼2×109 m3 of lava, reinforcing the idea that submarine lava eruptions are important in the growth of oceanic island volcanoes even after they emerged above sea level.

Investigating microbial colonization in actively forming hydrothermal deposits using thermocouple arrays

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

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

NASA Astrophysics Data System (ADS)

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

2010-12-01

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

Electrochemical cell having improved pressure vent

DOEpatents

Dean, Kevin; Holland, Arthur; Fillmore, Donn

1993-01-01

The electrochemical cell of the instant invention includes a case having a gas outlet, one or more positive electrodes positioned within the case, one or more negative electrodes positioned within the case electrode separators positioned between the positive and negative electrodes, electrolyte positioned within the case, and a pressure vent for releasing internal pressure occurring in the case to the surrounding atmosphere. The pressure vent is affixed to the case covering the gas outlet, the pressure vent includes a vent housing having a hollow interior area in gaseous communication with the surrounding atmosphere and the interior of the case via the gas outlet, a pressure release piston positioned within the hollow interior area, the pressure release piston sized to surround the gas outlet and having a seal groove configured to encapsulate all but one surface of a seal mounted within the seal groove, leaving the non-encapsulated surface of the seal exposed, and a compression spring positioned to urge the pressure release piston to compress the seal in the seal groove and block the gas outlet in the case.

46 CFR 153.351 - Location of 4m vent discharges.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Location of 4m vent discharges. 153.351 Section 153.351 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS... Venting Systems § 153.351 Location of 4m vent discharges. Except as prescribed in § 153.353, a 4m venting...

Characterization of On-Orbit U.S. Lab Condensate Vacuum Venting

NASA Astrophysics Data System (ADS)

Schmidl, W. D.; Alred, J. A.; Mikatarian, R.; Soares, C.; Miles, E.

2002-01-01

The venting of liquid streams into a vacuum has been studied extensively for many years. An experiment was performed aboard the International Space Station (ISS) to video tape the U.S. Lab's condensate venting event with cameras located on the Space Station Remote Manipulator System (SSRMS). Images of the vent plume were acquired close to both the port and starboard vent nozzles. The imaging started with a wider view and then zoomed in closer before the shutdown phase of the vent event occurred. The objective of this experiment was to extend our understanding of the properties of venting liquids into space. Data from the video images were analyzed to obtain the approximate cone angle encompassing the core of the vent plume. The condensate vent plume was characterized as having three phases, a startup phase, a nominal phase, and a shutdown phase. The startup phase consisted of the initial period when the vent first started and the liquid first entered the heated line. The nominal phase was the period when the majority of the liquid was vented. The shutdown phase occurs close to the end of the vent event. The shutdown phase was further divided into two parts, the shutdown initial phase, and a later shutdown sputtering phase. The shutdown initial phase occurs when gas becomes entrained in the condensate liquid being vented. The sputtering phase occurred after the vent valve was closed, and the liquid/ice in the line was removed by continuing to heat the line to bake it out. It was determined that the ice particles were ejected at higher angles, but lower velocities, during the startup and shutdown phases. The number and velocities of ice particles ejected outside of the core region, during the startup, initial shutdown and shutdown sputtering phases were determined. The core of liquid ejected during the startup and shutdown phases was contained within a half cone angle of less than 60 degrees. The startup phase took approximately 36 seconds, the shutdown initial phase

3D photo mosaicing of Tagiri shallow vent field by an autonomous underwater vehicle (3rd report) - Mosaicing method based on navigation data and visual features -

NASA Astrophysics Data System (ADS)

Maki, Toshihiro; Ura, Tamaki; Singh, Hanumant; Sakamaki, Takashi

Large-area seafloor imaging will bring significant benefits to various fields such as academics, resource survey, marine development, security, and search-and-rescue. The authors have proposed a navigation method of an autonomous underwater vehicle for seafloor imaging, and verified its performance through mapping tubeworm colonies with the area of 3,000 square meters using the AUV Tri-Dog 1 at Tagiri vent field, Kagoshima bay in Japan (Maki et al., 2008, 2009). This paper proposes a post-processing method to build a natural photo mosaic from a number of pictures taken by an underwater platform. The method firstly removes lens distortion, invariances of color and lighting from each image, and then ortho-rectification is performed based on camera pose and seafloor estimated by navigation data. The image alignment is based on both navigation data and visual characteristics, implemented as an expansion of the image based method (Pizarro et al., 2003). Using the two types of information realizes an image alignment that is consistent both globally and locally, as well as making the method applicable to data sets with little visual keys. The method was evaluated using a data set obtained by the AUV Tri-Dog 1 at the vent field in Sep. 2009. A seamless, uniformly illuminated photo mosaic covering the area of around 500 square meters was created from 391 pictures, which covers unique features of the field such as bacteria mats and tubeworm colonies.

Some features of the trace metal biogeochemistry in the deep-sea hydrothermal vent fields (Menez Gwen, Rainbow, Broken Spur at the MAR and 9°50‧N at the EPR): A synthesis

NASA Astrophysics Data System (ADS)

Demina, Ludmila L.; Holm, Nils G.; Galkin, Sergey V.; Lein, Alla Yu.

2013-10-01

Along with summarizing the published literature and our own data some new results on properties of the trace metal biogeochemistry in the deep-sea hydrothermal ecosystems at the Mid-Atlantic Ridge (MAR) and East Pacific Rise (EPR) are shown. Differences in mean concentrations of big group of trace metals (Fe, Mn, Zn, Cu, Ni, Cr, Co, As, Pb, Cd, Ag, Hg) between the biotope water of the low- and high-temperature hydrothermal vent fields were firstly revealed. The same trace metals were studied in different groups of organisms within different temperature zones at one and the same vent field (9°50‧N EPR), as well as in fauna inhabiting geochemically different vent sites. Distribution patterns of Fe, Mn, Zn, Cu, Cd, Pb, Ag, Ni, Cr, Co, As, Se, Sb, and Hg in different taxa gave an evidence of the influence of environmental and biological parameters on their bioaccumulation in organisms. Among the animals a particular “champion” with respect to the trace metal content was found to be a polychaeta Alvinella pompejana that inhabits the hottest places of the vent sulfide chimneys of the 9°50‧N field, EPR. New data on the trace metal distribution between soft tissues and carbonate shell let us estimate a role of biomineralization in the accumulation of metals in the Bathimodiolus mussels. Contrasting geochemical behavior was revealed for Cu that is enriched in soft tissues of mussels and depleted in shells, on the one hand, and Mn that is accumulated almost totally in mussel shells, on the other hand. Deep-sea hydrothermal biological communities demonstrate a strong concentration function, and bioconcentration factors (BCF) of trace metals estimated for Bathimodiolus mussels collected at the four hydrothermal fields vary within the limits of n102-n105 and are similar to that of the littoral mussels. Due to this and to the high values of biomasses per square meter, the hydrothermal fauna may be considered as a newly discovered biological filter of the oceans.

14 CFR 34.11 - Standard for fuel venting emissions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Section 34.11 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT FUEL VENTING AND EXHAUST EMISSION REQUIREMENTS FOR TURBINE ENGINE POWERED AIRPLANES Engine Fuel Venting Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No...

14 CFR 34.11 - Standard for fuel venting emissions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Section 34.11 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT FUEL VENTING AND EXHAUST EMISSION REQUIREMENTS FOR TURBINE ENGINE POWERED AIRPLANES Engine Fuel Venting Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No...

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

40 CFR 63.1406 - Reactor batch process vent provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Reactor batch process vent provisions... § 63.1406 Reactor batch process vent provisions. (a) Emission standards. Owners or operators of reactor... reactor batch process vent located at a new affected source shall control organic HAP emissions by...

40 CFR 63.1406 - Reactor batch process vent provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Reactor batch process vent provisions... § 63.1406 Reactor batch process vent provisions. (a) Emission standards. Owners or operators of reactor... reactor batch process vent located at a new affected source shall control organic HAP emissions by...

Automatic protective vent has fail-safe feature

NASA Technical Reports Server (NTRS)

Dameron, C. E.

1966-01-01

Delayed vent valve system in a mechanical backing pump in a vacuum system allows the pneumatic foreline valve to seal before the pump vent opens. The system is designed to be fail-safe and operate even though there is loss of electrical power.

Coil spring venting arrangement

DOEpatents

McCugh, R.M.

1975-10-21

A simple venting device for trapped gas pockets in hydraulic systems is inserted through a small access passages, operated remotely, and removed completely. The device comprises a small diameter, closely wound coil spring which is pushed through a guide temporarily inserted in the access passage. The guide has a central passageway which directs the coil spring radially upward into the pocket, so that, with the guide properly positioned for depth and properly oriented, the coil spring can be pushed up into the top of the pocket to vent it. By positioning a seal around the free end of the guide, the spring and guide are removed and the passage is sealed.

Long-term tilt and acceleration data from the Logatchev Hydrothermal Vent Field, Mid-Atlantic Ridge, measured by the Bremen Ocean Bottom Tiltmeter

NASA Astrophysics Data System (ADS)

Fabian, Marcus; Villinger, Heinrich

2008-07-01

Long-term seafloor deformations in the Logatchev Hydrothermal Vent Field (LHF) at the Mid-Atlantic Ridge are largely unexplored and unknown, even though the LHF has been the focus of international research for many years. As seafloor tilt and vertical acceleration provide key information about seafloor deformations, the Bremen Ocean Bottom Tiltmeter (OBT) was deployed in May 2005 at position 14°45'11.7″N, 44°58'47.0″W, 3035 m water depth in the LHF. The OBT recorded 384 days and was recovered in January 2007. Strong tilt steps and strong gradual tilt changes over less than a minute to days in the range of some 10 mrad and aligned mostly with the topography possibly indicate nearby mass movements like avalanches of bulk material due to local uplift or subsidence or may show tectonic activity. A vertically aligned high-resolution microelectromechanical systems (MEMS) accelerometer of type Servo K-Beam in the sensor package seems to be helpful to distinguish between tilt signals caused by a true rotation and fake tilt related to a transient translational motion of the OBT in a horizontal direction. Hodographs show elliptic motion patterns with about 1 mrad total tilt amplitude and distinct orientations of tilt toward hydrothermal vents. It is up to speculation whether the latter signals are related to hydrothermal fluid circulation. The amplitude spectra of these tilt signals and acceleration show discrete lines mostly between 0.1 and 50 mHz. The spectra show the periodic character of those signals and also proof that tides or bottom currents, which are known to show lower signal frequencies, or tremor, which generally has higher frequencies, are most likely not the reason. Compared with studies onshore and offshore, the LHF is most likely an area of strong and highly variable seafloor deformations.

Simulating Electrochemistry of Hydrothermal Vents on Enceladus and Other Ocean Worlds

NASA Astrophysics Data System (ADS)

Barge, L. M.; Krause, F. C.; Jones, J. P.; Billings, K.; Sobron, P.

2017-12-01

Gradients generated in hydrothermal systems provide a significant source of free energy for chemosynthetic life, and may play a role in present-day habitability on ocean worlds such as Enceladus that are thought to host hydrothermal activity. Hydrothermal vents are similar in some ways to typical fuel cell devices: redox/pH gradients between seawater and hydrothermal fluid are analogous to the oxidant and fuel reservoirs; conductive natural mineral deposits are analogous to electrodes; and, in hydrothermal chimneys, the porous chimney wall can function as a separator or ion-exchange membrane. Electrochemistry, founded on quantitative study of redox and other chemical disequilibria as well as the chemistry of interfaces, is uniquely suited to studying these systems. We have performed electrochemical studies to better understand the catalytic potential of seafloor minerals and vent chimneys, using samples from a black smoker vent chimney as an initial demonstration. Fuel cell experiments with electrodes made from black smoker chimney material accurately simulated the redox reactions that occur in a geological setting with this particular catalyst. Similar methods with other geo-catalysts (natural or synthetic) could be utilized to test which redox reactions or metabolisms could be driven in other hydrothermal systems, including putative vent systems on other worlds.

Life and Death of Deep-Sea Vents: Bacterial Diversity and Ecosystem Succession on Inactive Hydrothermal Sulfides

PubMed Central

Sylvan, Jason B.; Toner, Brandy M.; Edwards, Katrina J.

2012-01-01

ABSTRACT Hydrothermal chimneys are a globally dispersed habitat on the seafloor associated with mid-ocean ridge (MOR) spreading centers. Active, hot, venting sulfide structures from MORs have been examined for microbial diversity and ecology since their discovery in the mid-1970s, and recent work has also begun to explore the microbiology of inactive sulfides—structures that persist for decades to millennia and form moderate to massive deposits at and below the seafloor. Here we used tag pyrosequencing of the V6 region of the 16S rRNA and full-length 16S rRNA sequencing on inactive hydrothermal sulfide chimney samples from 9°N on the East Pacific Rise to learn their bacterial composition, metabolic potential, and succession from venting to nonventing (inactive) regimes. Alpha-, beta-, delta-, and gammaproteobacteria and members of the phylum Bacteroidetes dominate all inactive sulfides. Greater than 26% of the V6 tags obtained are closely related to lineages involved in sulfur, nitrogen, iron, and methane cycling. Epsilonproteobacteria represent <4% of the V6 tags recovered from inactive sulfides and 15% of the full-length clones, despite their high abundance in active chimneys. Members of the phylum Aquificae, which are common in active vents, were absent from both the V6 tags and full-length 16S rRNA data sets. In both analyses, the proportions of alphaproteobacteria, betaproteobacteria, and members of the phylum Bacteroidetes were greater than those found on active hydrothermal sulfides. These shifts in bacterial population structure on inactive chimneys reveal ecological succession following cessation of venting and also imply a potential shift in microbial activity and metabolic guilds on hydrothermal sulfides, the dominant biome that results from seafloor venting. PMID:22275502

Diverse styles of submarine venting on the ultra-slow spreading Mid-Cayman Rise (Invited)

NASA Astrophysics Data System (ADS)

German, C. R.; Bowen, A.; Coleman, M. L.; Honig, D. L.; Huber, J. A.; Jakuba, M.; Kinsey, J. C.; Kurz, M. D.; Leroy, S.; McDermott, J.; Mercier de Lepinay, B. F.; Nakamura, K.; Seewald, J.; Smith, J.; Sylva, S.; van Dover, C. L.; Whitcomb, L. L.; Yoerger, D. R.

2010-12-01

Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise collected using a combination of CTD-rosette operations and dives of the Hybrid Remotely Operated Vehicle (HROV) Nereus in 2009 followed by shore based work-up of samples for geochemical and microbiological analyses. Our data indicate that the Mid-Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.

Evidence for early life in Earth’s oldest hydrothermal vent precipitates

USGS Publications Warehouse

Dodd, Matthew S.; Papineau, Dominic; Grenne, Tor; Slack, John F.; Rittner, Martin; Pirajno, Franco; O’Neil, Jonathan; Little, Crispin T.S.

2017-01-01

Although it is not known when or where life on Earth began, some of the earliest habitable environments may have been submarine-hydrothermal vents. Here we describe putative fossilized microorganisms that are at least 3,770 million and possibly 4,280 million years old in ferruginous sedimentary rocks, interpreted as seafloor-hydrothermal vent-related precipitates, from the Nuvvuagittuq belt in Quebec, Canada. These structures occur as micrometre-scale haematite tubes and filaments with morphologies and mineral assemblages similar to those of filamentous microorganisms from modern hydrothermal vent precipitates and analogous microfossils in younger rocks. The Nuvvuagittuq rocks contain isotopically light carbon in carbonate and carbonaceous material, which occurs as graphitic inclusions in diagenetic carbonate rosettes, apatite blades intergrown among carbonate rosettes and magnetite–haematite granules, and is associated with carbonate in direct contact with the putative microfossils. Collectively, these observations are consistent with an oxidized biomass and provide evidence for biological activity in submarine-hydrothermal environments more than 3,770 million years ago.

Experimental investigation of passive thermodynamic vent system (TVS) with liquid nitrogen

NASA Astrophysics Data System (ADS)

Bae, Junhyuk; Yoo, Junghyun; Jin, Lingxue; Jeong, Sangkwon

2018-01-01

Thermodynamic vent system (TVS) is an attractive technology to maintain an allowable pressure level of a cryogenic propellant storage in a spacecraft under micro-gravity condition. There are two types of TVS; active or passive. In this paper, the passive TVS which does not utilize a cryogenic liquid circulation pump is experimentally investigated with liquid nitrogen and numerically analyzed by thermodynamic and heat transfer model. A cylindrical copper tank, which is 198 mm in inner diameter and 216 mm in height, is utilized to suppress a thermal-stratification effect of inside cryogenic fluid. A coil heat exchanger, which is 3 m in length and 6.35 mm in outer diameter, and a fixed size orifice of which diameter is 0.4 mm are fabricated to remove heat from the stored fluid to the vented flow. Each vent process is initiated at 140 kPa and ended at 120 kPa with liquid nitrogen fill levels which are 30%, 50% and 70%, respectively. In the numerical model, the fluid in the tank is assumed to be homogeneous saturated liquid-vapor. Mass and energy balance equations with heat transfer conditions suggested in this research are considered to calculate the transient pressure variation in the tank and the amount of heat transfer across the heat exchanger. We achieve the average heat rejection rate of more than 9 W by TVS and conclude that the passive TVS operates satisfactorily. In addition, the prediction model is verified by experimental results. Although the model has limitation in providing accurate results, it can surely predict the tendency of pressure and temperature changes in the tank. Furthermore, the model can suggest how we can improve the heat exchanger design to enhance an overall efficiency of passive TVS. Moreover, the performance of passive TVS is compared with other cryogenic vent systems (direct vent system and active TVS) by suggested performance indicator.

Bacterial Diets of Primary Consumers at Hydrothermal Vents

NASA Astrophysics Data System (ADS)

Govenar, B.; Shank, T. M.

2008-12-01

Chemical energy produced by mixing hydrothermal fluids and seawater supports dense biological communities on mid-ocean ridges. The base of the food web at deep-sea hydrothermal vents is formed by chemolithoautotrophic bacteria that use the energy from the oxidation of reduced chemicals to fix inorganic carbon into simple sugars. With the exception of a few species that have chemolithoautotropic bacterial symbionts, most of the vent-endemic macrofauna are heterotrophs that feed on free-living bacteria, protists, and other invertebrates. The most abundant and diverse group of primary consumers in hydrothermal vent communities belong to the Gastropoda, particularly the patellomorph limpets. Gastropod densities can be as high as 2000 individuals m-2, and there can be as many as 13 species of gastropods in a single aggregation of the siboglinid tubeworm Riftia pachyptila and more than 40 species along the East Pacific Rise. Some gastropods are ubiquitous and others are found in specific microhabitats, stages of succession, or associated with different foundation species. To determine the mechanisms of species coexistence (e.g. resource partitioning or competition) among hydrothermal vent primary consumers and to track the flow of energy in hydrothermal vent communities, we employed molecular genetic techniques to identify the gut contents of four species of co-occurring hydrothermal vent gastropods, Eulepetopsis vitrea, Lepetodrilus elevatus, Lepetodrilus ovalis and Lepetodrilus pustulosus, collected from a single diffuse-flow hydrothermal vent site on the East Pacific Rise. Unique haplotypes of the 16S gene that fell among the epsilon-proteobacteria were found in the guts of every species, and two species had gut contents that were similar only to epsilon-proteobacteria. Two species had gut contents that also included haplotypes that clustered with delta-proteobacteria, and one species had gut contents that clustered with alpha- proteobacteria. Differences in the diets

Retrieving eruptive vent conditions from dynamical properties of unsteady volcanic plume using high-speed imagery and numerical simulations

NASA Astrophysics Data System (ADS)

Tournigand, Pierre-Yves; Taddeucci, Jacopo; José Peña Fernandez, Juan; Gaudin, Damien; Sesterhenn, Jörn; Scarlato, Piergiorgio; Del Bello, Elisabetta

2016-04-01

Vent conditions are key parameters controlling volcanic plume dynamics and the ensuing different hazards, such as human health issues, infrastructure damages, and air traffic disruption. Indeed, for a given magma and vent geometry, plume development and stability over time mainly depend on the mass eruption rate, function of the velocity and density of the eruptive mixture at the vent, where direct measurements are impossible. High-speed imaging of eruptive plumes and numerical jet simulations were here non-dimensionally coupled to retrieve eruptive vent conditions starting from measurable plume parameters. High-speed videos of unsteady, momentum-driven volcanic plumes (jets) from Strombolian to Vulcanian activity from three different volcanoes (Sakurajima, Japan, Stromboli, Italy, and Fuego, Guatemala) were recorded in the visible and the thermal spectral ranges by using an Optronis CR600x2 (1280x1024 pixels definition, 500 Hz frame rate) and a FLIR SC655 (640x480 pixels definition, 50 Hz frame rate) cameras. Atmospheric effects correction and pre-processing of the thermal videos were performed to increase measurement accuracy. Pre-processing consists of the extraction of the plume temperature gradient over time, combined with a temperature threshold in order to remove the image background. The velocity and the apparent surface temperature fields of the plumes, and their changes over timescales of tenths of seconds, were then measured by particle image velocimetry and thermal image analysis, respectively, of the pre-processed videos. The parameters thus obtained are representative of the outer plume surface, corresponding to its boundary shear layer at the interface with the atmosphere, and may significantly differ from conditions in the plume interior. To retrieve information on the interior of the plume, and possibly extrapolate it even at the eruptive vent level, video-derived plume parameters were non-dimensionally compared to the results of numerical

The NOAA/PMEL Vents Program - 1983 to 2013: A History of Deep-Sea Volcanic and Hydrothermal Exploration and Research

NASA Astrophysics Data System (ADS)

Hammond, S. R.; Baker, E. T.; Embley, R. W.

2015-12-01

Inspiration for the Vents program arose from two serendipitous events: the discovery of seafloor spreading-center hydrothermal venting on the Galápagos Rift in 1977, and NOAA's deployment of the first US civilian research multibeam bathymetric sonar on the NOAA Ship Surveyor in 1979. Multibeam mapping in the NE Pacific revealed an unprecedented and revolutionary perspective of the Gorda and Juan de Fuca spreading centers, thus stimulating a successful exploration for volcanic and hydrothermal activity at numerous locations along both. After the 1986 discovery of the first "megaplume,", quickly recognized as the water column manifestation of a deep submarine volcanic eruption, the Vents program embarked on a multi-decadal effort to discover and understand local-, regional-, and, ultimately, global-scale physical, chemical, and biological ocean environmental impacts of submarine volcanism and hydrothermal venting. The Vents program made scores of scientific discoveries, many of which owed their success to the program's equally innovative and productive technological prowess. These discoveries were documented in hundreds of peer-reviewed papers by Vents researchers and their colleagues around the world. An emblematic success was the internationally recognized, first-ever detection, location, and study of an active deep volcanic eruption in 1993. To continue the Vents mission and further enhance its effectiveness in marine science and technology innovation, the program was reorganized in 2014 into two distinct, but closely linked, programs: Earth-Oceans Interactions and Acoustics. Both are currently engaged in expeditions and projects that maintain the Vents tradition of pioneering ocean exploration and research.

Vented Tank Resupply Experiment--Flight Test Results

NASA Technical Reports Server (NTRS)

Chato, David J.; Martin, Timothy A.

1997-01-01

This paper reports the results of the Vented Tank Resupply Experiment (VTRE) which was flown as a payload on STS 77. VTRE looks at the ability of vane Propellant Management Devices (PMD) to separate liquid and gas in low gravity. VTRE used two clear 0.8 cubic foot tanks one spherical and one with a short barrel section and transferred Refrigerant 113 between them as well as venting it to space. Tests included retention of liquid during transfer, liquid free venting, and recovery of liquid into the PMD after thruster firing. Liquid was retained successfully at the highest flow rate tested (2.73 gpm). Liquid free vents were achieved for both tanks, although at a higher flow rate (0.1591 cfm) for the spherical tank than the other (0.0400 cfm). Recovery from a thruster firing which moved the liquid to the opposite end of the tank from the PMD was achieved in 30 seconds.

40 CFR 63.450 - Standards for enclosures and closed-vent systems.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-vent systems. 63.450 Section 63.450 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Standards for enclosures and closed-vent systems. (a) Each enclosure and closed-vent system specified in..., or repairs. (c) Each component of the closed-vent system used to comply with §§ 63.443(c), 63.444(b...

40 CFR 63.450 - Standards for enclosures and closed-vent systems.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-vent systems. 63.450 Section 63.450 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Standards for enclosures and closed-vent systems. (a) Each enclosure and closed-vent system specified in..., or repairs. (c) Each component of the closed-vent system used to comply with §§ 63.443(c), 63.444(b...

40 CFR 63.450 - Standards for enclosures and closed-vent systems.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-vent systems. 63.450 Section 63.450 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Standards for enclosures and closed-vent systems. (a) Each enclosure and closed-vent system specified in..., or repairs. (c) Each component of the closed-vent system used to comply with §§ 63.443(c), 63.444(b...

40 CFR 63.450 - Standards for enclosures and closed-vent systems.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-vent systems. 63.450 Section 63.450 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Standards for enclosures and closed-vent systems. (a) Each enclosure and closed-vent system specified in..., or repairs. (c) Each component of the closed-vent system used to comply with §§ 63.443(c), 63.444(b...

40 CFR 63.450 - Standards for enclosures and closed-vent systems.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-vent systems. 63.450 Section 63.450 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Standards for enclosures and closed-vent systems. (a) Each enclosure and closed-vent system specified in..., or repairs. (c) Each component of the closed-vent system used to comply with §§ 63.443(c), 63.444(b...

Widespread introgression in deep-sea hydrothermal vent mussels.

PubMed

Breusing, Corinna; Vrijenhoek, Robert C; Reusch, Thorsten B H

2017-01-13

The analysis of hybrid zones is crucial for gaining a mechanistic understanding of the process of speciation and the maintenance of species boundaries. Hybrid zones have been studied intensively in terrestrial and shallow-water ecosystems, but very little is known about their occurrence in deep-sea environments. Here we used diagnostic, single nucleotide polymorphisms in combination with one mitochondrial gene to re-examine prior hypotheses about a contact zone involving deep-sea hydrothermal vent mussels, Bathymodiolus azoricus and B. puteoserpentis, living along the Mid-Atlantic Ridge. Admixture was found to be asymmetric with respect to the parental species, while introgression was more widespread geographically than previously recognized. Admixed individuals with a majority of alleles from one of the parental species were most frequent in habitats corresponding to that species. Mussels found at a geographically intermediate vent field constituted a genetically mixed population that showed no evidence for hybrid incompatibilities, a finding that does not support a previously inferred tension zone model. Our analyses indicate that B. azoricus and B. puteoserpentis hybridize introgressively across a large geographic area without evidence for general hybrid incompatibilities. While these findings shed new light onto the genetic structure of this hybrid zone, many aspects about its nature still remain obscure. Our study sets a baseline for further research that should primarily focus on the acquisition of additional mussel samples and environmental data, a detailed exploration of vent areas and hidden populations as well as genomic analyses in both mussel hosts and their bacterial symbionts.

Staged venting of fuel cell system during rapid shutdown

DOEpatents

Clingerman, Bruce J.; Doan, Tien M.; Keskula, Donald H.

2002-01-01

A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H.sub.2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H.sub.2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

Staged venting of fuel cell system during rapid shutdown

DOEpatents

Keskula, Donald H.; Doan, Tien M.; Clingerman, Bruce J.

2004-09-14

A venting methodology and system for rapid shutdown of a fuel cell apparatus of the type used in a vehicle propulsion system. H.sub.2 and air flows to the fuel cell stack are slowly bypassed to the combustor upon receipt of a rapid shutdown command. The bypass occurs over a period of time (for example one to five seconds) using conveniently-sized bypass valves. Upon receipt of the rapid shutdown command, the anode inlet of the fuel cell stack is instantaneously vented to a remote vent to remove all H.sub.2 from the stack. Airflow to the cathode inlet of the fuel cell stack gradually diminishes over the bypass period, and when the airflow bypass is complete the cathode inlet is also instantaneously vented to a remote vent to eliminate pressure differentials across the stack.

The morphology and evolution of the Stromboli 2002-2003 lava flow field--An example of a basaltic flow field emplaced on a steep slope

USGS Publications Warehouse

Lodato, Luigi; Harris, A.; Spampinato, L.; Calvari, Sonia; Dehn, J.; Patrick, M.

2007-01-01

The use of a hand-held thermal camera during the 2002–2003 Stromboli effusive eruption proved essential in tracking the development of flow field structures and in measuring related eruption parameters, such as the number of active vents and flow lengths. The steep underlying slope on which the flow field was emplaced resulted in a characteristic flow field morphology. This comprised a proximal shield, where flow stacking and inflation caused piling up of lava on the relatively flat ground of the vent zone, that fed a medial–distal lava flow field. This zone was characterized by the formation of lava tubes and tumuli forming a complex network of tumuli and flows linked by tubes. Most of the flow field was emplaced on extremely steep slopes and this had two effects. It caused flows to slide, as well as flow, and flow fronts to fail frequently, persistent flow front crumbling resulted in the production of an extensive debris field. Channel-fed flows were also characterized by development of excavated debris levees in this zone (Calvari et al. 2005). Collapse of lava flow fronts and inflation of the upper proximal lava shield made volume calculation very difficult. Comparison of the final field volume with that expecta by integrating the lava effusion rates through time suggests a loss of ~70% erupted lava by flow front crumbling and accumulation as debris flows below sea level. Derived relationships between effusion rate, flow length, and number of active vents showed systematic and correlated variations with time where spreading of volume between numerous flows caused an otherwise good correlation between effusion rate, flow length to break down. Observations collected during this eruption are useful in helping to understand lava flow processes on steep slopes, as well as in interpreting old lava–debris sequences found in other steep-sided volcanoes subject to effusive activity.

Submarine radial vents on Mauna Loa Volcano, Hawaìi

NASA Astrophysics Data System (ADS)

Wanless, V. Dorsey; Garcia, M. O.; Trusdell, F. A.; Rhodes, J. M.; Norman, M. D.; Weis, Dominique; Fornari, D. J.; Kurz, M. D.; Guillou, Hervé

2006-05-01

A 2002 multibeam sonar survey of Mauna Loa's western flank revealed ten submarine radial vents and three submarine lava flows. Only one submarine radial vent was known previously. The ages of these vents are constrained by eyewitness accounts, geologic relationships, Mn-Fe coatings, and geochemical stratigraphy; they range from 128 years B.P. to possibly 47 ka. Eight of the radial vents produced degassed lavas despite eruption in water depths sufficient to inhibit sulfur degassing. These vents formed truncated cones and short lava flows. Two vents produced undegassed lavas that created "irregular" cones and longer lava flows. Compositionally and isotopically, the submarine radial vent lavas are typical of Mauna Loa lavas, except two cones that erupted alkalic lavas. He-Sr isotopes for the radial vent lavas follow Mauna Loa's evolutionary trend. The compositional and isotopic heterogeneity of these lavas indicates most had distinct parental magmas. Bathymetry and acoustic backscatter results, along with photography and sampling during four JASON2 dives, are used to produce a detailed geologic map to evaluate Mauna Loa's submarine geologic history. The new map shows that the 1877 submarine eruption was much larger than previously thought, resulting in a 10% increase for recent volcanism. Furthermore, although alkalic lavas were found at two radial vents, there is no systematic increase in alkalinity among these or other Mauna Loa lavas as expected for a dying volcano. These results refute an interpretation that Mauna Loa's volcanism is waning. The submarine radial vents and flows cover 29 km2 of seafloor and comprise a total volume of ˜2 × 109 m3 of lava, reinforcing the idea that submarine lava eruptions are important in the growth of oceanic island volcanoes even after they emerged above sea level.

Sill intrusion in volcanic calderas: implications for vent opening probability

NASA Astrophysics Data System (ADS)

Giudicepietro, Flora; Macedonio, Giovanni; Martini, Marcello; D'Auria, Luca

2017-04-01

Calderas show peculiar behaviors with remarkable dynamic processes, which do not often culminate in eruptions. Observations and studies conducted in recent decades have shown that the most common cause of unrest in the calderas is due to magma intrusion; in particular, the intrusion of sills at shallow depths. Monogenic cones, with large areal dispersion, are quite common in the calderas, suggesting that the susceptibility analysis based on geological features, is not strictly suitable for estimating the vent opening probability in calderas. In general, the opening of a new eruptive vent can be regarded as a rock failure process. The stress field in the rocks that surrounds and tops the magmatic reservoirs plays an important role in causing the rock failure and creating the path that magma can follow towards the surface. In this conceptual framework, we approach the problem of getting clues about the probability of vent opening in volcanic calderas through the study of the stress field produced by the intrusion of magma, in particular, by the intrusion of a sill. We simulate the intrusion of a sill free to expand radially, with shape and dimensions which vary with time. The intrusion process is controlled by the elastic response of the rock plate above the sill, which bends because of the intrusion, and by gravity, that drives the magma towards the zones where the thickness of the sill is smaller. We calculated the stress field in the plate rock above the sill. We found that at the bottom of the rock plate above the sill the maximum intensity of tensile stress is concentrated at the front of the sill and spreads radially with it, over time. For this reason, we think that the front of the spreading sill is prone to open for eruptive vents. Even in the central area of the sill the intensity of stress is relatively high, but at the base of the rock plate stress is compressive. Under isothermal conditions, the stress soon reaches its maximum value (time interval

Gas discharges from the Kueishantao hydrothermal vents, offshore northeast Taiwan: Implications for drastic variations of magmatic/hydrothermal activities

NASA Astrophysics Data System (ADS)

Chen, Xue-Gang; Lyu, Shuang-Shuang; Zhang, Ping-Ping; Yu, Ming-Zhen; Chen, Chen-Tung Arthur; Chen, Yun-Jie; Li, Xiaohu; Jin, Aimin; Zhang, Hai-Yan; Duan, Wei; Ye, Ying

2018-03-01

The chemical compositions of gas discharges from the Kueishantao (KST) hydrothermal field changed dramatically from 2000 to 2014. In this study, we established a gas mixing model for the KST gases. The N2, Ar, and CO2 contents were mixed from a magmatic endmember with CO2 of about 990 mmol/mol, a hydrothermal and an atmospheric endmember enriched in N2 and Ar. More than 71% KST gas components were mantle-derived/magmatic. The calculated endmember N2/Ar ratio and Ar contents of the hydrothermal endmember (percolated fluid) are about 140 and 5.28-5.52 mmol/mol, respectively. This relatively elevated N2/Ar ratio was probably caused by the thermogenic addition of N2. The log(CH4/CO2) values of the KST gas samples correlate well with the mixing temperature that estimated from the mixing ratio between the percolated fluid and the magmatic endmember. It is indicated that the KST CH4 and CO2 may have attained chemical equilibrium. The temporal variations of the KST gas compositions are determined by the mixing ratio, which is dependent on the magmatic activity underneath the KST field. With the decreasing of magmatic activity since 2005, the proportion of the hydrothermal endmember increased, along with the increasing of N2, Ar, and CH4 contents. This study proposed an effective model to quantitatively assess the sources of gas components discharged from submarine hydrothermal vents. In addition, it is suggested that the mixing between a magmatic and a hydrothermal endmember may play an important role in the concentrations of CO2 and CH4 in hydrothermal gas discharges.

Characterizing the Morphology, Distribution, and Formation Geometry of Mercury's Pyroclastic Vents

NASA Astrophysics Data System (ADS)

Jozwiak, L. M.; Head, J. W.; Wilson, L.

2018-05-01

We present a final catalog of pyroclastic vents on Mercury, identifying 104 candidate pyroclastic vents. We then assess the vent distribution, morphologic variation, and probable formation geometries.

Explosion hazards of LPG-air mixtures in vented enclosure with obstacles.

PubMed

Zhang, Qi; Wang, Yaxing; Lian, Zhen

2017-07-15

Numerical simulations were performed to study explosion characteristics of liquefied petroleum gas (LPG) explosion in enclosure with a vent. Unlike explosion overpressure and dynamic pressure, explosion temperature of the LPG-air mixture at a given concentration in a vented enclosure has very little variation with obstacle numbers for a given blockage ratio. For an enclosure without obstacle, explosion overpressures for the stoichiometric mixtures and the fuel-lean mixtures reach their maximum within the vent and that for fuel-rich mixture reaches its maximum beyond and near the vent. Dynamic pressures produced by an indoor LPG explosion reach their maximum always beyond the vent no matter obstacles are present or not in the enclosure. A LPG explosion in a vented enclosure with built-in obstacles is strong enough to make the brick and mortar wall with a thickness of 370mm damaged. If there is no obstacle in the enclosure, the lower explosion pressure of several kPa can not break the brick and mortar wall with a thickness of 370mm. For a LPG explosion produced in an enclosure with a vent, main hazards, within the vent, are overpressure and high temperature. However main hazards are dynamic pressure, blast wind, and high temperature beyond the vent. Copyright © 2017 Elsevier B.V. All rights reserved.

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

Statistical Analysis of Time-Series from Monitoring of Active Volcanic Vents

NASA Astrophysics Data System (ADS)

Lachowycz, S.; Cosma, I.; Pyle, D. M.; Mather, T. A.; Rodgers, M.; Varley, N. R.

2016-12-01

Despite recent advances in the collection and analysis of time-series from volcano monitoring, and the resulting insights into volcanic processes, challenges remain in forecasting and interpreting activity from near real-time analysis of monitoring data. Statistical methods have potential to characterise the underlying structure and facilitate intercomparison of these time-series, and so inform interpretation of volcanic activity. We explore the utility of multiple statistical techniques that could be widely applicable to monitoring data, including Shannon entropy and detrended fluctuation analysis, by their application to various data streams from volcanic vents during periods of temporally variable activity. Each technique reveals changes through time in the structure of some of the data that were not apparent from conventional analysis. For example, we calculate the Shannon entropy (a measure of the randomness of a signal) of time-series from the recent dome-forming eruptions of Volcán de Colima (Mexico) and Soufrière Hills (Montserrat). The entropy of real-time seismic measurements and the count rate of certain volcano-seismic event types from both volcanoes is found to be temporally variable, with these data generally having higher entropy during periods of lava effusion and/or larger explosions. In some instances, the entropy shifts prior to or coincident with changes in seismic or eruptive activity, some of which were not clearly recognised by real-time monitoring. Comparison with other statistics demonstrates the sensitivity of the entropy to the data distribution, but that it is distinct from conventional statistical measures such as coefficient of variation. We conclude that each analysis technique examined could provide valuable insights for interpretation of diverse monitoring time-series.

Zero-gravity venting of three refrigerants

NASA Technical Reports Server (NTRS)

Labus, T. L.; Aydelott, J. C.; Amling, G. E.

1974-01-01

An experimental investigation of venting cylindrical containers partially filled with initially saturated liquids under zero-gravity conditions was conducted in the NASA Lewis Research Center 5-second zero-gravity facility. The effect of interfacial mass transfer on the ullage pressure response during venting was analytically determined, based on a conduction analysis applied to an infinitely planer (flat) liquid-vapor interface. This pressure response was compared with both the experimental results and an adiabatic decompression computation.

Investigating the role of small vent volcanism during the development of Tharsis Province, Mars

NASA Astrophysics Data System (ADS)

Richardson, J. A.; Bleacher, J. E.; Connor, C.; Connor, L.; Glaze, L. S.

2014-12-01

Clusters of tens to hundreds of small volcanic vents have recently been recognized as a major component of Tharsis Province volcanism. These volcanic fields are formed from distributed-style, possibly monogenetic, volcanism and are composed of low sloped edifices with diameters of tens of kilometers and heights of tens to hundreds of meters. We report a new catalog of these small volcanic vents, now available through the USGS Astrogeology Science Center. This catalog was created with the use of gridded topographic data from the Mars Orbiter Laser Altimeter (MOLA) and images from the Thermal Emission Imaging System (THEMIS) and the High Resolution Stereo Camera (HRSC). We are now investigating isolated clusters of distributed volcanism in Tharsis with this dataset. We hypothesize that these clusters are formed from significant magmatic events that played a large role in the development of Tharsis. Currently, the catalog contains 1075 unique volcanic vents in the Tharsis Province. With the catalog, potentially isolated volcano clusters are identified with vent density estimation. Vent intensity for clusters is found to be 1 vent per 1000 sq km or less. Crater retention rates for one such cluster, Syria Planum, indicates that these distributed volcanic systems might continue as long as 700 Ma, or that monogenetic volcanic systems overprint older systems. Using a modified basal outlining algorithm with MOLA gridded data, shield volumes are found to be between 1-20 cubic km. Current results show distributed-style volcanism occuring in Tharsis orders of magnitude more dispersed than analogous volcano clusers on Earth, while individual edifices are found to be an order of magnitude larger than volcanoes in Earth clusters. Proof of concept results are reported for three identified clusters: Arsia Mons Caldera, Syria Planum, and Southern Pavonis Mons.

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

Assessment of Literature Related to Combustion Appliance Venting Systems

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

Rapp, V. H.; Less, B. D.; Singer, B. C.

In many residential building retrofit programs, air tightening to increase energy efficiency is often constrained by safety concerns with naturally vented combustion appliances. Tighter residential buildings more readily depressurize when exhaust equipment is operated, making combustion appliances more prone to backdraft or spill combustion exhaust into the living space. Several measures, such as installation guidelines, vent sizing codes, and combustion safety diagnostics, are in place with the intent to prevent backdrafting and combustion spillage, but the diagnostics conflict and the risk mitigation objective is inconsistent. This literature review summarizes the metrics and diagnostics used to assess combustion safety, documents theirmore » technical basis, and investigates their risk mitigations. It compiles information from the following: codes for combustion appliance venting and installation; standards and guidelines for combustion safety diagnostics; research evaluating combustion safety diagnostics; research investigating wind effects on building depressurization and venting; and software for simulating vent system performance.« less

40 CFR 63.1430 - Process vent reporting and recordkeeping requirements.

Code of Federal Regulations, 2013 CFR

2013-07-01

... is subject to the Group 1 batch process vent control requirements for nonepoxide HAP emissions from...) Records to demonstrate compliance. The owner or operator complying with the process vent control...: (1) When using a flare to comply with the process vent control requirements in § 63.1425(b)(2)(i), (c...

Thermodynamic Vent System Test in a Low Earth Orbit Simulation

NASA Technical Reports Server (NTRS)

VanOverbeke, Thomas J.

2004-01-01

A thermodynamic vent system for a cryogenic nitrogen tank was tested in a vacuum chamber simulating oxygen storage in low earth orbit. The nitrogen tank was surrounded by a cryo-shroud at -40 F. The tank was insulated with two layers of multi-layer insulation. Heat transfer into cryogenic tanks causes phase change and increases tank pressure which must be controlled. A thermodynamic vent system was used to control pressure as the location of vapor is unknown in low gravity and direct venting would be wasteful. The thermodynamic vent system consists of a Joule-Thomson valve and heat exchanger installed on the inlet side of the tank mixer-pump. The combination is used to extract thermal energy from the tank fluid, reducing temperature and ullage pressure. The system was sized so that the tank mixer-pump operated a small fraction of the time to limit motor heating. Initially the mixer used sub-cooled liquid to cool the liquid-vapor interface inducing condensation and pressure reduction. Later, the thermodynamic vent system was used. Pressure cycles were performed until steady-state operation was demonstrated. Three test runs were conducted at tank fills of 97, 80, and 63 percent. Each test was begun with a boil-off test to determine heat transfer into the tank. The lower tank fills had time averaged vent rates very close to steady-state boil-off rates showing the thermodynamic vent system was nearly as efficient as direct venting in normal gravity.

Turbofan Engine Core Compartment Vent Aerodynamic Configuration Development Methodology

NASA Technical Reports Server (NTRS)

Hebert, Leonard J.

2006-01-01

This paper presents an overview of the design methodology used in the development of the aerodynamic configuration of the nacelle core compartment vent for a typical Boeing commercial airplane together with design challenges for future design efforts. Core compartment vents exhaust engine subsystem flows from the space contained between the engine case and the nacelle of an airplane propulsion system. These subsystem flows typically consist of precooler, oil cooler, turbine case cooling, compartment cooling and nacelle leakage air. The design of core compartment vents is challenging due to stringent design requirements, mass flow sensitivity of the system to small changes in vent exit pressure ratio, and the need to maximize overall exhaust system performance at cruise conditions.

40 CFR 63.1407 - Non-reactor batch process vent provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Non-reactor batch process vent... § 63.1407 Non-reactor batch process vent provisions. (a) Emission standards. (1) Owners or operators of non-reactor batch process vents located at new or existing affected sources with 0.25 tons per year (0...

40 CFR 63.1407 - Non-reactor batch process vent provisions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Non-reactor batch process vent... § 63.1407 Non-reactor batch process vent provisions. (a) Emission standards. (1) Owners or operators of non-reactor batch process vents located at new or existing affected sources with 0.25 tons per year (0...

Stratigraphic architecture of hydromagmatic volcanoes that have undergone vent migration: a review of Korean case studies

NASA Astrophysics Data System (ADS)

Sohn, Y.

2011-12-01

Recent studies show that the architecture of hydromagmatic volcanoes is far more complex than formerly expected. A number of external factors, such as paleohydrology and tectonics, in addition to magmatic processes are thought to play a role in controlling the overall characteristics and architecture of these volcanoes. One of the main consequences of these controls is the migration of the active vent during eruption. Case studies of hydromagmatic volcanoes in Korea show that those volcanoes that have undergone vent migration are characterized by superposition or juxtaposition of multiple rim deposits of partial tuff rings and/or tuff cones that have contrasting lithofacies characteristics, bed attitudes, and paleoflow directions. Various causes of vent migration are inferred from these volcanoes. Large-scale collapse of fragile substrate is interpreted to have caused vent migration in the Early Pleistocene volcanoes of Jeju Island, which were built upon still unconsolidated continental shelf sediments. Late Pleistocene to Holocene volcanoes, which were built upon a stack of rigid, shield-forming lava flows, lack features due to large-scale substrate collapse and have generally simple and circular morphologies either of a tuff ring or of a tuff cone. However, ~600 m shift of the eruptive center is inferred from one of these volcanoes (Ilchulbong tuff cone). The vent migration in this volcano is interpreted to have occurred because the eruption was sourced by multiple magma batches with significant eruptive pauses in between. The Yangpori diatreme in a Miocene terrestrial half-graben basin in SE Korea is interpreted to be a subsurface equivalent of a hydromagmatic volcano that has undergone vent migration. The vent migration here is inferred to have had both vertical and lateral components and have been caused by an abrupt tectonic activity near the basin margin. In all these cases, rimbeds or diatreme fills derived from different source vents are bounded by either

46 CFR 153.350 - Location of B/3 vent discharges.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Location of B/3 vent discharges. 153.350 Section 153.350 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS... Venting Systems § 153.350 Location of B/3 vent discharges. Except as prescribed in § 153.353, a B/3...

Submarine fissure eruptions and hydrothermal vents on the southern Juan de Fuca Ridge: preliminary observations from the submersible Alvin

USGS Publications Warehouse

Normark, W.R.

1986-01-01

The submersible Alvin was used to investigate 3 active hydrothermal discharge sites along the S Juan de Fuca Ridge in September 1984. The hydrothermal zones occur within a 10-30m-deep, 30-50m-wide cleft marking the center of the axial valley. This cleft is the eruptive locus for the axial valley. The hydrothermal vents coincide with the main eruptive vents along the cleft. Each hydrothermal zone has multiple discharge sites extending as much as 500m along the cleft. Sulfide deposits occur as clusters (15-100m2 area) of small chimneys (= or <2m high) and as individual and clustered fields of large, branched chimneys (= or <10m high). Recovered sulfide samples are predominantly the tops of chimneys and spires and typically contain more than 80% sphalerite and wurtzite with minor pyrrhotite, pyrite, marcasite, isocubanite, chalcopyrite, anhydrite, anhydrite, and amorphous silica. The associated hydrothermal fluids have the highest chlorinity of any reported to date.-Authors

Investigations Into Tank Venting for Propellant Resupply

NASA Technical Reports Server (NTRS)

Hearn, H. C.; Harrison, Robert A. (Technical Monitor)

2002-01-01

Models and simulations have been developed and applied to the evaluation of propellant tank ullage venting, which is integral to one approach for propellant resupply. The analytical effort was instrumental in identifying issues associated with resupply objectives, and it was used to help develop an operational procedure to accomplish the desired propellant transfer for a particular storable bipropellant system. Work on the project was not completed, and several topics have been identified as requiring further study; these include the potential for liquid entrainment during the low-g and thermal/freezing effects in the vent line and orifice. Verification of the feasibility of this propellant venting and resupply approach still requires additional analyses as well as testing to investigate the fluid and thermodynamic phenomena involved.

Nanoparticulate, sub-micron and micron sized particles emanating from hydrothermal vents

NASA Astrophysics Data System (ADS)

Luther, G. W., III; Gartman, A.; Findlay, A.; Yucel, M.; Chan, C. S. Y.

2015-12-01

Recent data from Geotraces cruises over the MAR and SEPR indicate dissolved and particulate Fe enrichment in waters 1000 and 4000 km from their vent sources, respectively. Deep-sea hydrothermal vents and the waters in the reactive mixing zone above vent orifices have been suggested to be an important source of fine material that can pass through normal filters (0.2 and 0.4 μm). In this work, nanoparticles are defined operationally as that which can pass through a 0.2 μm filter. We investigated two vent sites (Lau Basin and the MAR). Chimneys from both vent sites have fluids that can be sulfide rich or metal rich. We also present chemical and physical chemical data (SEM-EDS, TEM, XRD, EELS) showing some of the materials found in these (nano)particulate phases including pyrite, metal sulfides, silicate and aluminosilicate material. Enrichment of Mg and K in the latter suggest that reverse weathering may occur in the waters within 1-2 meters of the vent orifice where vent waters mix with cold oxygenated bottom waters.

On Small Disturbance Ascent Vent Behavior

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2015-01-01

As a spacecraft undergoes ascent in a launch vehicle, its ambient pressure environment transitions from one atmosphere to high vacuum in a matter of a few minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. These pressure differentials are often restricted to low levels to prevent violation of container integrity. Such vents usually consist of fixed orifices, ducts, or combinations of both. Duct conductance behavior is fundamentally different from that for orifices in pressure driven flows governing the launch vehicle ascent depressurization environment. Duct conductance is governed by the average pressure across its length, while orifice conductance is dictated by a pressure ratio. Hence, one cannot define a valid equivalent orifice for a given duct across a range of pressure levels. This presentation discusses development of expressions for these two types of vent elements in the limit of small pressure differentials, explores conditions for their validity, and compares their features regarding ascent depressurization performance.

46 CFR 153.352 - B/3 and 4 m venting system outlets.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 5 2011-10-01 2011-10-01 false B/3 and 4 m venting system outlets. 153.352 Section 153.352 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES... Cargo Venting Systems § 153.352 B/3 and 4 m venting system outlets. A B/3 or 4 m venting system outlet...

46 CFR 153.352 - B/3 and 4 m venting system outlets.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false B/3 and 4 m venting system outlets. 153.352 Section 153.352 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES... Cargo Venting Systems § 153.352 B/3 and 4 m venting system outlets. A B/3 or 4 m venting system outlet...

40 CFR 63.1321 - Batch process vents provisions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1321 Batch process vents..., owners and operators of new and existing affected sources with batch process vents shall comply with the... applicable reporting requirements in § 63.1327. (b) New SAN batch affected sources. Owners and operators of...

46 CFR 56.50-85 - Tank-vent piping.

Code of Federal Regulations, 2012 CFR

2012-10-01

... this requirement. (4) Tank vents must extend above the weather deck, except vents from fresh water tanks, bilge oily-water holding tanks, bilge slop tanks, and tanks containing Grade E combustible... barges in inland service and for Great Lakes vessels, the height from the deck to any point where water...

46 CFR 56.50-85 - Tank-vent piping.

Code of Federal Regulations, 2014 CFR

2014-10-01

... this requirement. (4) Tank vents must extend above the weather deck, except vents from fresh water tanks, bilge oily-water holding tanks, bilge slop tanks, and tanks containing Grade E combustible... barges in inland service and for Great Lakes vessels, the height from the deck to any point where water...

46 CFR 56.50-85 - Tank-vent piping.

Code of Federal Regulations, 2013 CFR

2013-10-01

... this requirement. (4) Tank vents must extend above the weather deck, except vents from fresh water tanks, bilge oily-water holding tanks, bilge slop tanks, and tanks containing Grade E combustible... barges in inland service and for Great Lakes vessels, the height from the deck to any point where water...

40 CFR 264.1087 - Standards: Closed-vent systems and control devices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Closed-vent systems and control devices. 264.1087 Section 264.1087 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY....1087 Standards: Closed-vent systems and control devices. (a) This section applies to each closed-vent...

Management of turbidity current venting in reservoirs under different bed slopes.

PubMed

Chamoun, Sabine; De Cesare, Giovanni; Schleiss, Anton J

2017-12-15

The lifetime and efficiency of dams is endangered by the process of sedimentation. To ensure the sustainable use of reservoirs, many sediment management techniques exist, among which venting of turbidity currents. Nevertheless, a number of practical questions remain unanswered due to a lack of systematic investigations. The present research introduces venting and evaluates its performance using an experimental model. In the latter, turbidity currents travel on a smooth bed towards the dam and venting is applied through a rectangular bottom outlet. The combined effect of outflow discharge and bed slopes on the sediment release efficiency of venting is studied based on different criteria. Several outflow discharges are tested using three different bed slopes (i.e., 0%, 2.4% and 5.0%). Steeper slopes yield higher venting efficiency. Additionally, the optimal outflow discharge leading to the largest venting efficiency with the lowest water loss increases when moving from the horizontal bed to the inclined positions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Exopolysaccharides Isolated from Hydrothermal Vent Bacteria Can Modulate the Complement System

PubMed Central

Courtois, Anthony; Berthou, Christian; Guézennec, Jean

2014-01-01

The complement system is involved in the defence against bacterial infection, or in the elimination of tumour cells. However, disturbances in this system contributes to the pathogenesis of various inflammatory diseases. The efficiency of therapeutic anti-tumour antibodies is enhanced when the complement system is stimulated. In contrast, cancer cells are able to inhibit the complement system and thus proliferate. Some marine molecules are currently being developed as new drugs for use in humans. Among them, known exopolyssacharides (EPSs) generally originate from fungi, but few studies have been performed on bacterial EPSs and even fewer on EPSs extracted from deep-sea hydrothermal vent microbes. For use in humans, these high molecular weight EPSs must be depolymerised. Furthermore, the over-sulphation of EPSs can modify their biological activity. The aim of this study was to investigate the immunodulation of the complement system by either native or over-sulphated low molecular weight EPSs isolated from vent bacteria in order to find pro or anti-activators of complement. PMID:24736648

Hydrothermal venting along Earth's fastest spreading center: East Pacific Rise, 27.5°-32.3°

NASA Astrophysics Data System (ADS)

Baker, E. T.; Hey, R. N.; Lupton, J. E.; Resing, J. A.; Feely, R. A.; Gharib, J. J.; Massoth, G. J.; Sansone, F. J.; Kleinrock, M.; Martinez, F.; Naar, D. F.; Rodrigo, C.; Bohnenstiehl, D.; Pardee, D.

2002-07-01

During March/April 1998 we conducted detailed mapping and sampling of hydrothermal plumes along six segments of Earth's fasting spreading mid-ocean ridge, 27.5°-32.3°S on the East Pacific Rise. We compared the distribution and chemistry of hydrothermal plumes to geological indicators of long-term (spreading rate) and moderate-term (ridge inflation) variations in magmatic budget. In this large-offset, propagating rift setting, these geological indices span virtually the entire range found along fast spreading ridges worldwide. Hydrothermal plumes overlaid ~60% of the length of superfast (>130 km/Myr) spreading axis surveyed and defined at least 14 separate vent fields. We observed no plumes over the slower spreading propagating segments. Finer-scale variations in the magmatic budget also correlated with hydrothermal activity, as the location of the five most intense plumes corresponded to subsegment peaks in ridge inflation. Along the entire ridge crest, the more inflated a ridge location the more likely it was to be overlain by a hydrothermal plume. Plume chemistry mostly reflected discharge from mature vent fields apparently unperturbed by magmatic activity within the last few years. Plume samples with high volatile/metal ratios, generally indicating recent seafloor volcanism, were scarce. Along-axis trends in both volatile (3He; CH4; ΔpH, a proxy for CO2; and particulate S) and nonvolatile (Fe, Mn) species showed a first-order agreement with the trend of ridge inflation. Nevertheless, a broad correspondence between the concentration of volatile species in plumes and geological proxies of magma supply identifies a pervasive magmatic imprint on this superfast spreading group of ridge segments.

Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps.

PubMed

Portail, Marie; Olu, Karine; Dubois, Stanislas F; Escobar-Briones, Elva; Gelinas, Yves; Menot, Lénaick; Sarrazin, Jozée

In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the

Food-Web Complexity in Guaymas Basin Hydrothermal Vents and Cold Seeps

PubMed Central

Olu, Karine; Dubois, Stanislas F.; Escobar-Briones, Elva; Gelinas, Yves; Menot, Lénaick; Sarrazin, Jozée

2016-01-01

In the Guaymas Basin, the presence of cold seeps and hydrothermal vents in close proximity, similar sedimentary settings and comparable depths offers a unique opportunity to assess and compare the functioning of these deep-sea chemosynthetic ecosystems. The food webs of five seep and four vent assemblages were studied using stable carbon and nitrogen isotope analyses. Although the two ecosystems shared similar potential basal sources, their food webs differed: seeps relied predominantly on methanotrophy and thiotrophy via the Calvin-Benson-Bassham (CBB) cycle and vents on petroleum-derived organic matter and thiotrophy via the CBB and reductive tricarboxylic acid (rTCA) cycles. In contrast to symbiotic species, the heterotrophic fauna exhibited high trophic flexibility among assemblages, suggesting weak trophic links to the metabolic diversity of chemosynthetic primary producers. At both ecosystems, food webs did not appear to be organised through predator-prey links but rather through weak trophic relationships among co-occurring species. Examples of trophic or spatial niche differentiation highlighted the importance of species-sorting processes within chemosynthetic ecosystems. Variability in food web structure, addressed through Bayesian metrics, revealed consistent trends across ecosystems. Food-web complexity significantly decreased with increasing methane concentrations, a common proxy for the intensity of seep and vent fluid fluxes. Although high fluid-fluxes have the potential to enhance primary productivity, they generate environmental constraints that may limit microbial diversity, colonisation of consumers and the structuring role of competitive interactions, leading to an overall reduction of food-web complexity and an increase in trophic redundancy. Heterogeneity provided by foundation species was identified as an additional structuring factor. According to their biological activities, foundation species may have the potential to partly release the

Payload bay atmospheric vent airflow testing at the Vibration and Acoustic Test Facility

NASA Technical Reports Server (NTRS)

Johnston, James D., Jr.

1988-01-01

Several concerns related to venting the Space Shuttle Orbiter payload bay during launch led to laboratory experiments with a flight-type vent box installed in the wall of a subsonic wind tunnel. This report describes the test setups and procedures used to acquire data for characterization of airflow through the vent box and acoustic tones radiated from the vent-box cavity. A flexible boundary-layer spoiler which reduced the vent-tone amplitude is described.

40 CFR 61.349 - Standards: Closed-vent systems and control devices.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Emission Standard for Benzene Waste Operations § 61.349 Standards: Closed-vent systems and control devices... efficiency of 95 weight percent or greater, or shall recover or control the benzene emissions vented to it..., or shall recover or control the benzene emissions vented to it with an efficiency of 98 weight...

40 CFR 61.349 - Standards: Closed-vent systems and control devices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Emission Standard for Benzene Waste Operations § 61.349 Standards: Closed-vent systems and control devices... efficiency of 95 weight percent or greater, or shall recover or control the benzene emissions vented to it..., or shall recover or control the benzene emissions vented to it with an efficiency of 98 weight...

40 CFR 63.491 - Batch front-end process vents-recordkeeping requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (b)(2): (i) For an incinerator or non-combustion control device, the percent reduction of organic HAP... the process vent stream is introduced with combustion air or is used as a secondary fuel and is not... combustion device to control halogenated batch front-end process vents or halogenated aggregate batch vent...

A quantitative look at the demise of a basaltic vent: The death of Kupaianaha, Kilauea Volcano, Hawai'i

USGS Publications Warehouse

Kauahikaua, J.; Mangan, M.; Heliker, C.; Mattox, T.

1996-01-01

The Kupaianaha vent, the source of the 48th episode of the 1983-to-present Pu'u 'O'o-Kupaianaha eruption, erupted nearly continuously from July 1986 until February 1992. This investigation documents the geophysical and geologic monitoring of the final 10 months of activity at the Kupaianaha vent. Detailed very low frequency (VLF) electromagnetic profiles across the single lava tube transporting lava from the vent were used to determine the cross-sectional area of the molten lava within the tube. Combined with measurements of lava velocity, these data provide an estimate of the lava output of Kupaianaha. In addition, lava temperatures (calculated from analysis of quenched glass) and bulk-rock chemistry were obtained for samples taken from the tube at the same site. The combined data set shows the lava flux from Kupaianaha vent declining linearly from 250000 m3/day in April 1991 to 54000 m3/day by November 1991. During that time surface breakouts of lava from weak points along the tube occurred progressively closer to the vent, consistent with declining efficiency in lava transport. There were no significant changes in lava temperature or in bulk MgO content during this period. Another eruptive episode (the 49th) began uprift of Kupaianaha on 8 November 1991 and erupted lava concurrently with Kupaianaha for 18 days. Lava flux from Kupaianaha decreased in response to this new episode, but the response was delayed by approximately 1 day. After 14 November 1991, lava velocities were no longer measurable in the tube because the lava stream beneath the skylight had crusted over; however, the VLF-derived electrical conductances documented the decreasing flux of molten lava through the tube. Kupaianaha remained active, but output continued to decrease until early February 1992 when the last active surface flows were seen. In November 1991 we used the linearly decreasing effusion rate to accurately predict the date for the death of the Kupaianaha vent. The linear nature of

A quantitative look at the demise of a basaltic vent: the death of Kupaianaha, Kilauea Volcano, Hawai'i

NASA Astrophysics Data System (ADS)

Kauahikaua, J.; Mangan, M.; Heliker, C.; Mattox, T.

1996-07-01

The Kupaianaha vent, the source of the 48th episode of the 1983-to-present Pu'u 'O'o Kupaianaha eruption, erupted nearly continuously from July 1986 until February 1992. This investigation documents the geophysical and geologic monitoring of the final 10 months of activity at the Kupaianaha vent. Detailed very low frequency (VLF) electromagnetic profiles across the single lava tube transporting lava from the vent were used to determine the cross-sectional area of the molten lava within the tube. Combined with measurements of lava velocity, these data provide an estimate of the lava output of Kupaianaha. In addition, lava temperatures (calculated from analysis of quenched glass) and bulk-rock chemistry were obtained for samples taken from the tube at the same site. The combined data set shows the lava flux from Kupaianaha vent declining linearly from 250 000 m3/day in April 1991 to 54 000 m3/day by November 1991. During that time surface breakouts of lava from weak points along the tube occurred progressively closer to the vent, consistent with declining efficiency in lava transport. There were no significant changes in lava temperature or in bulk MgO content during this period. Another eruptive episode (the 49th) began uprift of Kupaianaha on 8 November 1991 and erupted lava concurrently with Kupaianaha for 18 days. Lava flux from Kupaianaha decreased in response to this new episode, but the response was delayed by approximately 1 day. After 14 November 1991, lava velocities were no longer measurable in the tube because the lava stream beneath the skylight had crusted over; however, the VLF-derived electrical conductances documented the decreasing flux of molten lava through the tube. Kupaianaha remained active, but output continued to decrease until early February 1992 when the last active surface flows were seen. In November 1991 we used the linearly decreasing effusion rate to accurately predict the date for the death of the Kupaianaha vent. The linear nature of

Feeding behaviour: hydrothermal vent crabs feast on sea 'snow'.

PubMed

Jeng, M-S; Ng, N K; Ng, P K L

2004-12-23

The crab Xenograpsus testudinatus lives at enormously high densities around the sulphur-rich hydrothermal vents found in shallow waters off Taiwan, even though this acidic environment is low in nutrients. Here we show that these crabs swarm out of their crevices at slack water and feed on the vast numbers of zooplankton that are killed by the vents' sulphurous plumes, and that rain down like marine 'snow'. This opportunistic feeding behaviour explains how the crabs are able to survive in the adverse toxic environment of these shallow hydrothermal vents.

46 CFR 38.20-5 - Venting-T/ALL.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 1 2011-10-01 2011-10-01 false Venting-T/ALL. 38.20-5 Section 38.20-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Venting and Ventilation § 38.20-5 Venting—T/ALL. (a) Safety relief valves on cargo tanks in barges may be connected to...

46 CFR 38.20-5 - Venting-T/ALL.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Venting-T/ALL. 38.20-5 Section 38.20-5 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS LIQUEFIED FLAMMABLE GASES Venting and Ventilation § 38.20-5 Venting—T/ALL. (a) Safety relief valves on cargo tanks in barges may be connected to...

Adsorptive conversion of nitrogen dioxide from etching vent gases over activated carbon.

PubMed

Fang, Mei-Ling; Wu, Ching-Yi; Chou, Ming-Shean

2018-04-13

Some metal etching operations emit limited flow rates of waste gases with reddish-brown NO 2 fume, which may cause visual and acidic-odor complaints, as well as negative health effects. In this study, tests were performed by passing caustic-treated waste gases vented from Al-etching operations through columns packed either with virgin or regenerated granular activated carbon (GAC) to test their adsorptive conversion performance of NO 2 in the gases. The gases contained 5-55 ppm NO 2 and acetic and nitric acids of below 3 ppm. Exhausted carbon was regenerated by scrubbing it with caustic solution and water, and dried for further adsorption tests. Results indicate that with an (empty bed residence time (EBRT) of 0.15 sec for the gas through the GAC-packed space, around 60% of the influent NO 2 of 54 ppm could be removed, and 47% of the removed NO 2 was converted by and desorbed from the carbon as NO. GAC used in the present study could be regenerated at least twice to restore its capacity for NO 2 adsorption. Within EBRTs of 0.076-0.18 sec, the adsorptive conversion capacity was linearly varied with EBRT. In practice, with an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) -1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Some metal etching operations emit waste gases with reddish-brown (yellow when diluted) NO 2 fume which may cause visual and acidic-odor complaints, as well as negative health effects. This study provides a simple process for the adsorptive conversion of NO 2 in caustic-treated waste gases vented from metal-etching operations through a GAC column. With an EBRT of 0.20 sec, a conversion capacity of 0.80 kg NO 2 (kg GAC) -1 with an influent NO 2 of 40 ppm can be used as a basis for system design. Saturated GAC can be regenerated at least twice by simply scrubbing it with aqueous caustic solution.

Constraints of gas venting activity for the interstitial water geochemistry at the shallow gas hydrate site, eastern margin of the Japan Sea; results from high resolution time-series fluid sampling by OsmoSampler

NASA Astrophysics Data System (ADS)

Owari, S.; Tomaru, H.; Matsumoto, R.

2016-12-01

We have conducted ROV researches in the eastern margin of the Japan Sea where active gas venting and outcropping of gas hydrates were observed near the seafloor and have found the strength and location of venting had changed within a few days. These observations indicate the seafloor environments with the shallow gas hydrate system could have changed for short period compared to a geological time scale. We have applied a long-term osmotic fluid sampling system "OsmoSampler" on the active gas hydrate system for one year in order to document how the gas venting and gas hydrate activity have changed the geochemical environments near the seafloor. All the major ion concentrations in the interstitial water show synchronous increase and decrease repeatedly in three to five days, reflecting the incorporation and release of fresh water in gas hydrates in response to the gas concentration change near the sampling site. Dissolved methane concentration increases rapidly and excessively (over several mM) in the first 40 days corresponding to the active gas venting. The increases of methane concentration are often associated with high ion concentration during high water pressure period, indicating excess gas release from shallow gas pockets. Contrarily, enhanced gas hydrate growth may plug the fluid-gas paths in shallow sediment, reducing gas hydrate formation due to the decrease of methane flux. This study was conducted under the commission from AIST as a part of the methane hydrate research project funded by METI (the Ministry of Economy, Trade and Industry, Japan).

Effects of venting on wind noise levels measured at the eardrum.

PubMed

Chung, King

2013-01-01

Wind noise can be a nuisance to hearing aid users. With the advent of sophisticated feedback reduction algorithms, people with higher degrees of hearing loss are fit with larger vents than previously allowed, and more people with lesser degrees of hearing loss are fit with open hearing aids. The purpose of this study was to examine the effects of venting on wind noise levels in the ear canal for hearing aids with omnidirectional and directional microphones. Two behind-the-ear hearing aids were programmed when they were worn on a Knowles Electronics Manikin for Acoustic Research. The hearing aid worn on the right ear was programmed to the omnidirectional microphone mode and the one on the left to the directional microphone mode. The hearing aids were adjusted to linear amplification with flat frequency response in an anechoic chamber. Gains below 10 dB were used to avoid output limiting of wind noise levels at low input levels. Wind noise samples were recorded at the eardrum location in a wind tunnel at wind velocities ranging from a gentle to a strong breeze. The hearing aids were coupled to #13 tubings (i.e., open vent), or conventional skeleton earmolds with no vent, pressure vents, or 3mm vents. Polar and spectral characteristics of wind noise were analyzed off-line using MatLab programs. Wind noise levels in the ear canals were mostly predicted by vent-induced frequency response changes in the conventional earmold conditions for both omnidirectional and directional hearing aids. The open vent condition, however, yielded the lowest levels, which could not be entirely predicted by the frequency response changes of the hearing aids. This indicated that a wind-related vent effect permitted an additional amount of sound reduction in the ear canal, which could not be explained by known vent effects. For the microphone location, form factor, and gain settings tested, open fit hearing aids yielded lower noise levels at the eardrum location than conventional behind

Empirical Profiling of Cold Hydrogen Plumes Formed from Venting Of LH2 Storage Vessels: Preprint

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

Buttner, William J; Rivkin, Carl H; Schmidt, Kara

Liquid hydrogen (LH2) storage is a viable approach to assuring sufficient hydrogen capacity at commercial fuelling stations. Presently, LH2 is produced at remote facilities and then transported to the end-use site by road vehicles (i.e., LH2 tanker trucks). Venting of hydrogen to depressurize the transport storage tank is a routine part of the LH2 delivery process. The behaviour of cold hydrogen plumes has not been well-characterized because empirical field data is essentially non-existent. The NFPA 2 Hydrogen Storage Safety Task Group, which consists of hydrogen producers, safety experts, and CFD modellers, has identified the lack of understanding of hydrogen dispersionmore » during LH2 venting of storage vessel as a critical gap for establishing safety distances at LH2 facilities, especially commercial hydrogen fuelling stations. To address this need, the NREL sensor laboratory, in collaboration with the NFPA 2 Safety Task Group developed the Cold Hydrogen Plume Analyzer to empirically characterize the hydrogen plume formed during LH2 storage tank venting. A prototype Analyzer was developed and field-deployed at an actual LH2 venting operation with critical findings that included: - H2 being detected as much as 2 m lower than the release point, which is not predicted by existing models - A small and inconsistent correlation between oxygen depletion and the hydrogen concentration - A negligible to non-existent correlation between in-situ temperature and the hydrogen concentration The Analyzer is currently being upgraded for enhanced metrological capabilities including improved real-time spatial and temporal profiling of the plume and tracking of prevailing weather conditions. Additional deployments are planned to monitor plume behaviour under different wind, humidity, and temperatures. This data will be shared with the NFPA 2 Safety Task Group and ultimately will be used support theoretical models and code requirements prescribed in NFPA 2.« less

14 CFR 29.653 - Pressure venting and drainage of rotor blades.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pressure venting and drainage of rotor... § 29.653 Pressure venting and drainage of rotor blades. (a) For each rotor blade— (1) There must be means for venting the internal pressure of the blade; (2) Drainage holes must be provided for the blade...

14 CFR 27.653 - Pressure venting and drainage of rotor blades.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pressure venting and drainage of rotor....653 Pressure venting and drainage of rotor blades. (a) For each rotor blade— (1) There must be means for venting the internal pressure of the blade; (2) Drainage holes must be provided for the blade; and...

OPERATING PARAMETERS TO MINIMIZE EMISSIONS DURING ROTARY KILN EMERGENCY SAFETY VENT OPENINGS

EPA Science Inventory

Certain designs of hazardous waste incinerator systems include emergency safety vents (ESVs). ESVs (also called dump stacks, vent stacks, emergency by-pass stacks, thermal relief valves, and pressure relief valves) are regarded as true emergency devices. Their purpose is to vent ...

30 CFR 250.1160 - When may I flare or vent gas?

Code of Federal Regulations, 2014 CFR

2014-07-01

... Requirements Flaring, Venting, and Burning Hydrocarbons § 250.1160 When may I flare or vent gas? (a) You must... production facilities) or is used as an additive necessary to burn waste products, such as H2S The volume of gas flared or vented may not exceed the amount necessary for its intended purpose. Burning waste...

Response of key stress-related genes of the seagrass Posidonia oceanica in the vicinity of submarine volcanic vents

NASA Astrophysics Data System (ADS)

Lauritano, C.; Ruocco, M.; Dattolo, E.; Buia, M. C.; Silva, J.; Santos, R.; Olivé, I.; Costa, M. M.; Procaccini, G.

2015-03-01

Submarine volcanic vents are being used as natural laboratories to assess the effects of CO2 on marine organisms and communities, as this gas is the main component of emissions. Seagrasses should positively react to increased dissolved carbon, but in vicinity of volcanic vents there may be toxic substances, that can have indirect effects on seagrasses. Here we analysed the expression of 35 stress-related genes in the Mediterranean keystone seagrass species P. oceanica in the vicinity of submerged volcanic vents located in the Islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR) was used to characterize the expression levels of genes. Fifty one per cent of genes analysed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls both in Ischia and Panarea locations, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The expression levels of genes involved in free radical detoxification indicate that, in contrast with Ischia, P. oceanica at the Panarea vent face stressors that result in the production of reactive oxygen species triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. Overall, our study reveals that P. oceanica is generally under higher stress in the vicinity of the vents at Panarea than at Ischia, possibly resulting from environmental and evolutionary differences existing between the two volcanic sites. This is the first study analysing gene responses in marine plants living near natural CO2 vents and our results call for a careful consideration of factors, other than CO2 and acidification, that can cause stress to seagrasses and other organisms near volcanic vents.

Cultivation mutualism between a deep-sea vent galatheid crab and its chemosynthetic epibionts

NASA Astrophysics Data System (ADS)

Watsuji, Tomo-o.; Tsubaki, Remi; Chen, Chong; Nagai, Yukiko; Nakagawa, Satoshi; Yamamoto, Masahiro; Nishiura, Daisuke; Toyofuku, Takashi; Takai, Ken

2017-09-01

Since the discovery of deep-sea hydrothermal vents in 1977, chemosynthesis-based ecosystems have been found in a wide range of habitats, such as hydrocarbon seeps, coastal sediments and terrestrial caves. Several invertebrates found in dark ecosystems harbor chemosynthetic bacteria (epibionts) on the surfaces of their specialised tissues; in particular, a vent galatheid crab Shinkaia crosnieri consumes the epibionts thriving on their setae as the primary nutritional source. In this study, we found that the water stream is the key to the nutritional symbiosis between S. crosnieri and chemosynthetic epibionts. The chemosynthetic functions of epibionts were highly activated by the water flow, and observations in the laboratory supported rheotaxis by S. crosnieri. In addition, endogenous water flow generated by respiratory water ventilation of S. crosnieri stimulated the chemosynthetic activity of epibionts under static conditions. These results point out that the epibionts are cultivated by the active behaviors of S. crosnieri, potentially representing the first example of a cultivation mutualism in chemosynthetic ectosymbiosis.

Astronomical and atmospheric impacts on deep-sea hydrothermal vent invertebrates

PubMed Central

Legendre, Pierre; Matabos, Marjolaine; Mihály, Steve; Lee, Raymond W.; Sarradin, Pierre-Marie; Arango, Claudia P.; Sarrazin, Jozée

2017-01-01

Ocean tides and winter surface storms are among the main factors driving the dynamics and spatial structure of marine coastal species, but the understanding of their impact on deep-sea and hydrothermal vent communities is still limited. Multidisciplinary deep-sea observatories offer an essential tool to study behavioural rhythms and interactions between hydrothermal community dynamics and environmental fluctuations. Here, we investigated whether species associated with a Ridgeia piscesae tubeworm vent assemblage respond to local ocean dynamics. By tracking variations in vent macrofaunal abundance at different temporal scales, we provide the first evidence that tides and winter surface storms influence the distribution patterns of mobile and non-symbiotic hydrothermal species (i.e. pycnogonids Sericosura sp. and Polynoidae polychaetes) at more than 2 km depth. Local ocean dynamics affected the mixing between hydrothermal fluid inputs and surrounding seawater, modifying the environmental conditions in vent habitats. We suggest that hydrothermal species respond to these habitat modifications by adjusting their behaviour to ensure optimal living conditions. This behaviour may reflect a specific adaptation of vent species to their highly variable habitat. PMID:28381618

Quaternary fault-controlled volcanic vents and crustal thinning: new insights from the magma-rich Tyrrhenian passive margin (Italy)

NASA Astrophysics Data System (ADS)

Cardello, Giovanni Luca; Conti, Alessia; Consorti, Lorenzo; Do Couto, Damien

2017-04-01

The discover of monogenic Quaternary volcanic vents, that were recently mapped along major fault zones both inland and offshore the Tyrrhenian magma-rich passive margin, poses questions about: timing and role they had into Plio-Pleistocene crustal thinning with relevant consequences for the hazard assessment of an area inhabited by some 0.5 million people. The present-day margin is stretched over 100 km between the Volsci Range (VR) and the Pontian escarpment, being defined by moderate shallow seismicity (Mw≤4.6), relative high geothermal gradient and ongoing hydrothermal activity. Although major central volcanoes (e.g., Colli Albani), occurring at major fault intersections are well studied, smaller volcanic fields were so far unconstrained. Both field survey in the VR and offshore high-resolution geophysical data, allow us to: 1) better define the anatomy of the poorly known VR volcanic field; 2) furnish new insights on the regional Quaternary dynamics; 3) propose modes and reason of magma emplacement. The VR is composed of about 40 punctual and linear monogenic and mostly phreatomagmatic vents occurring at the edges of the Apennine carbonate fold-and-thrust belt and within the VR backbone. Volcanites are characterized by zeolitized to incoherent tuffs and surge deposits locally covered by lavas and slope deposits. Most explosive units host carbonate-rich lithics with different degrees of rounding and decarbonation, which frequently belong to Albian-Cenomanian aquifers. By comparing cross-section with lithic analyses we demonstrate that fragmentation, transport, progressive disintegration and decarbonation occur at multiple depths, depending on the fold-and-thrust belt setting. Thus, along the same vent zone, juvenile lithic composition proves repeated fragmentation within pressured-aquifers, testifying for fissural activity with implications for local seismic and volcanic assessment. Pyroclastic deposits occur as well in the Pontina and Fondi coastal plains at

76 FR 44457 - Application of Regulations on Fuel Venting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-26

... GEnx-2B and GEnx-1B engines, respectively. These GE engines include an advanced technology fuel system...-0746] Application of Regulations on Fuel Venting AGENCY: Federal Aviation Administration (FAA), DOT... regarding fuel venting requirements. DATES: We must receive your comments by August 25, 2011. ADDRESSES...

In-Situ pH Measurements in Mid-Ocean Ridge Hydrothermal Vent Fluids: Constraints on Subseafloor Alteration Processes at Crustal Depths

NASA Astrophysics Data System (ADS)

Schaen, A. T.; Ding, K.; Seyfried, W. E.

2013-12-01

Developments in electrochemistry and material science have facilitated the construction of ceramic (YSZ) based chemical sensor systems that can be used to measure and monitor pH and redox in aqueous fluids at elevated temperatures and pressures. In recent years, these sensor systems have been deployed to acquire real-time and time series in-situ data for high-temperature hydrothermal vent fluids at the Main Endeavour Field (Juan de Fuca Ridge), 9oN (East Pacific Rise), and at the ultramafic-hosted Rainbow field (36oN, Mid-Atlantic Ridge). Here we review in-situ pH data measured at these sites and apply these data to estimate the pH of fluids ascending to the seafloor from hydrothermal alteration zones deeper in the crust. In general, in-situ pH measured at virtually all vent sites is well in excess of that measured shipboard owing to the effects of temperature on the distribution of aqueous species and the solubility of metal sulfides, especially Cu and Zn, originally dissolved in the vent fluids. In situ pH measurements determined at MEF (Sully vent) and EPR 9oN (P-vent) in 2005 and 2008 were 4.4 ×0.02 and 5.05×0.05, respectively. The temperature and pressure (seafloor) of the vent fluids at each of the respective sites were 356oC and 220 bar, and 380oC and 250 bar. Plotting these data with respect to fluid density reveals that the in-situ pH of each vent fluid is approximately 1.5 pH units below neutrality. The density-pH (in-situ) correlation, however, is important because it provides a means from which the vent fluids were derived. Using dissolved silica and chloride from fluid samples at the MEF (Sully) suggest T/P conditions of approximately 435oC, 380 bar, based on quartz-fluid and NaCl-H2O systems. At the fluid density calculated for these conditions, pH (in-situ) is predicted to be ~6.2. Attempts are presently underway to assess the effect of the calculated pH on metal sulfide and silicate (e.g., plagioclase, chlorite) solubility in comparison with

Optical Detection of Organic Chemical Biosignatures at Hydrothermal Vents

NASA Technical Reports Server (NTRS)

Conrad, P. G.; Lane, A. L.; Bhartia, R.; Hug, W. H.

2004-01-01

We have developed a non-contact, optical life detection instrument that can detect organic chemical biosignatures in a number of different environments, including dry land, shallow aqueous, deep marine or in ice. Hence, the instrument is appropriate as a biosignature survey tool both for Mars exploration or in situ experiments in an ice-covered ocean such as one might wish to explore on Europa. Here, we report the results we obtained on an expedition aboard the Russian oceanographic vessel Akademik Mstislav Keldysh to hydrothermal vent sites in the Pacific Ocean using our life detection instrument MCDUVE, a multichannel, deep ultraviolet excitation fluorescence detector. MCDUVE detected organic material distribution on rocks near the vent, as well as direct detection of organisms, both microbial and microscopic. We also were able to detect organic material issuing directly from vent chimneys, measure the organic signature of the water column as we ascended, and passively observe the emission of light directly from some vents.

The use of photo-mosaics, bathymetry and sensor data into geographic information system for site description and faunal distribution analysis at the Menez Gwen Hydrothermal vent field

NASA Astrophysics Data System (ADS)

Marcon, Y.; Sahling, H.; Bohrmann, G.

2012-04-01

The Menez Gwen hydrothermal vent is located on the Mid-Atlantic Ridge at a depth of about 800m. Although it has been the focus of several expeditions and studies, the sites of active venting at Menez Gwen are still under described, and it is not possible to get a global picture of the sites from the published data. Exploration of deep-sea environments is commonly performed using remotely operated vehicles (ROV) equipped with sensors, cameras and powerful lights. But strong attenuation of light in the deep-sea constrains visual surveys to be carried out from a few meters only above the seafloor, thus limiting the extent of the field of view. Moreover, ROV-mounted positioning systems usually lack accuracy and cannot be relied on for accurate relative positioning of sensor measurements, samplings, and features of interest. Such limitations are hindrances for many applications. In particular, site description or mapping of deep-sea benthic fauna over an area of study usually requires lengthy surveys, and reliability of navigation data becomes a major issue. Also, studying small-scale spatial variations of a physicochemical parameter needs positions of sensor measurements or samplings to be known precisely. To overcome this problem, maps of the seafloor can be generated in the form of geo-referenced video- or photo-mosaics. Mosaics are constructed by assembling overlapping images together into a larger image of the scene. To reduce the effects of drift in the navigation data, the construction of the mosaics uses robust feature detection and mapping capabilities to precisely relate consecutive images together. After geo-referencing in a Geographic Information System (GIS), points of measurements and sampling can be accurately pinpointed onto the mosaics to allow for spatial analyses. During cruise M82/3 to the Menez Gwen hydrothermal vent system, high-resolution photo-mosaics of several sites of hydrothermal activity were constructed and geo-referenced into GIS systems

Ephemerality of discrete methane vents in lake sediments

USGS Publications Warehouse

Scandella, Benjamin P.; Pillsbury, Liam; Weber, Thomas; Ruppel, Carolyn D.; Hemond, Harold F.; Juanes, Ruben

2016-01-01

Methane is a potent greenhouse gas whose emission from sediments in inland waters and shallow oceans may both contribute to global warming and be exacerbated by it. The fraction of methane emitted by sediments that bypasses dissolution in the water column and reaches the atmosphere as bubbles depends on the mode and spatiotemporal characteristics of venting from the sediments. Earlier studies have concluded that hot spots—persistent, high-flux vents—dominate the regional ebullitive flux from submerged sediments. Here the spatial structure, persistence, and variability in the intensity of methane venting are analyzed using a high-resolution multibeam sonar record acquired at the bottom of a lake during multiple deployments over a 9 month period. We confirm that ebullition is strongly episodic, with distinct regimes of high flux and low flux largely controlled by changes in hydrostatic pressure. Our analysis shows that the spatial pattern of ebullition becomes homogeneous at the sonar's resolution over time scales of hours (for high-flux periods) or days (for low-flux periods), demonstrating that vents are ephemeral rather than persistent, and suggesting that long-term, lake-wide ebullition dynamics may be modeled without resolving the fine-scale spatial structure of venting.

Predicting Backdrafting and Spillage for Natural-Draft Gas Combustion Appliances: Validating VENT-II

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

Rapp, Vi H.; Pastor-Perez, Albert; Singer, Brett C.

2013-04-01

VENT-II is a computer program designed to provide detailed analysis of natural draft and induced draft combustion appliance vent-systems (i.e., furnace or water heater). This program is capable of predicting house depressurization thresholds that lead to backdrafting and spillage of combustion appliances; however, validation reports of the program being applied for this purpose are not readily available. The purpose of this report is to assess VENT-II’s ability to predict combustion gas spillage events due to house depressurization by comparing VENT-II simulated results with experimental data for four appliance configurations. The results show that VENT-II correctly predicts depressurizations resulting in spillagemore » for natural draft appliances operating in cold and mild outdoor conditions, but not for hot conditions. In the latter case, the predicted depressurizations depend on whether the vent section is defined as part of the vent connector or the common vent when setting up the model. Overall, the VENTII solver requires further investigation before it can be used reliably to predict spillage caused by depressurization over a full year of weather conditions, especially where hot conditions occur.« less

Effects of Hemagglutination Activity in the Serum of a Deep-Sea Vent Endemic Crab, Shinkaia Crosnieri, on Non-Symbiotic and Symbiotic Bacteria

PubMed Central

Fujiyoshi, So; Tateno, Hiroaki; Watsuji, Tomoo; Yamaguchi, Hideyuki; Fukushima, Daisuke; Mino, Sayaka; Sugimura, Makoto; Sawabe, Tomoo; Takai, Ken; Sawayama, Shigeki; Nakagawa, Satoshi

2015-01-01

In deep-sea hydrothermal environments, most invertebrates associate with dense populations of symbiotic microorganisms in order to obtain nutrition. The molecular interactions between deep-sea animals and environmental microbes, including their symbionts, have not yet been elucidated in detail. Hemagglutinins/lectins, which are carbohydrate-binding proteins, have recently been reported to play important roles in a wide array of biological processes, including the recognition and control of non-self materials. We herein assessed hemagglutination activity in the serum of a deep-sea vent endemic crab, Shinkaia crosnieri, which harbors chemosynthetic epibionts on its plumose setae. Horse and rabbit erythrocytes were agglutinated using this serum (opt. pH 7.5 and opt. temperature 15°C). Agglutinating activity was inhibited by eight kinds of sugars and several divalent cations, did not require any divalent metal ions, and remained detectable even after heating the serum at 100°C for 30 min. By using fluorescently labeled serum, we demonstrated that deep-sea crab serum components bound to the epibionts even in the presence of sugars. This study represents the first immunological assessment of a deep-sea vent endemic crab and demonstrated the possibility of a non-lectin-mediated symbiont-host interaction. PMID:26212518

SEAFLOOR MANIFESTATIONS OF GAS VENTING AND NEAR SEAFLOOR GAS HYDRATE OCCURRENCES

NASA Astrophysics Data System (ADS)

Paull, C. K.; Ussler, W.; Caress, D. W.; Thomas, H.; Lundsten, E.; Riedel, M.; Lapham, L.

2009-12-01

High-resolution multibeam bathymetry and chirp seismic profiles collected with an AUV complimented by ROV observations and sampling reveal the fine scale geomorphology and seafloor structures associated with gas venting and/or near subsurface gas hydrate accumulations along the Pacific North American continental margin. Sites from Santa Monica Basin, northern and southern Hydrate Ridge, Barkley Canyon, Bullseye Vent and three previously unexplored vent sites near Bullseye Vent have been recently investigated. The new AUV data allow the identification of features and seafloor textures that were previously undetected and reveal the impact of gas venting, gas hydrate development and related phenomena on the seafloor morphology. Distinct geomorphic characteristics are interpreted to represent different stages in the development and evolution of the seafloor in these areas. The more mature features include distinct (>10 m high) elevated features (e.g., Santa Monica Mounds and the Hydrate Ridge Pinnacle), widespread areas where methane-derived carbonates are exposed on the surrounding seafloor (e.g., both Hydrate Ridge sites, and an unnamed ridge north of Bullseye Vent), circular seafloor craters with diameters of 3 to 50 m that appear to be associated with missing sections of the original seafloor (e.g., Bullseye Vent, northern Hydrate Ridge, and an unnamed ridge north of Bullseye Vent). Smaller mound-like features (<10 m in diameter and 1-3 m higher than the surrounding seafloor occur at Barkley Canyon and a newly explored vent system called Spinnaker Vent 6 km NW of Bullseye vent. Solid lens of gas hydrate are occasionally exposed along fractures on the sides of these mounds and suggest that these are push-up features associated with gas hydrate growth within the near seafloor sediments. The existence of both extensive methane-derived carbonates and chemosynthetic biological communities characterized by Vesicomya clams and Lamellibrachia tubeworms (which are slow

Medium Fidelity Simulation of Oxygen Tank Venting

NASA Technical Reports Server (NTRS)

Sweet, Adam; Kurien, James; Lau, Sonie (Technical Monitor)

2001-01-01

The item to he cleared is a medium-fidelity software simulation model of a vented cryogenic tank. Such tanks are commonly used to transport cryogenic liquids such as liquid oxygen via truck, and have appeared on liquid-fueled rockets for decades. This simulation model works with the HCC simulation system that was developed by Xerox PARC and NASA Ames Research Center. HCC has been previously cleared for distribution. When used with the HCC software, the model generates simulated readings for the tank pressure and temperature as the simulated cryogenic liquid boils off and is vented. Failures (such as a broken vent valve) can be injected into the simulation to produce readings corresponding to the failure. Release of this simulation will allow researchers to test their software diagnosis systems by attempting to diagnose the simulated failure from the simulated readings. This model does not contain any encryption software nor can it perform any control tasks that might be export controlled.

Isotopic Approaches to Allying Productivity and Sulfur Metabolism in Three Symbiotic Hydrothermal Vent Molluscs

NASA Astrophysics Data System (ADS)

Beinart, R.; Gartman, A.; Sanders, J. G.; Luther, G. W.; Girguis, P. R.

2012-12-01

Symbioses between animals and chemosynthetic bacteria predominate at hydrothermal vents. In these associations, the endosymbiotic bacteria utilize chemical reductants for the energy to support autotrophy, providing primary nutrition for the host. Despite their ubiquity at vents worldwide, little is known about the rates of productivity of these symbioses under different physico-chemical regimes or how their metabolism effects the local geochemical environment. To address this matter, we used high-pressure flow through incubations and stable isotopic tracers to maintain three genera of symbiotic mollusc - the gastropods Alviniconcha and Ifremeria, and the mussel Bathymodiolus - at vent-like conditions. Via the incorporation of isotopically labeled compounds, we assessed their productivity when using different reduced sulfur species as reductants. Using cyclic voltammetry, mass spectrometry and discrete geochemical analyses, we concurrently measured their effect on sulfur flux from the vessels. We found that the symbionts of all three genera can support autotrophy with hydrogen sulfide and thiosulfate, though at different rates. Additionally, by examining the rate of isotopic incorporation into biomass, we revealed intra-generic variability in productivity among the individuals in our experimental assemblages that are likely related to differences in the geochemical regime along the length of reactor. These geochemical gradients are due to the activity of other individuals within the vessel, since those organisms closest to the influent of the vent-like water had the highest measured carbon incorporation. Finally, we measured the uptake and excretion of sulfur species, which illustrate the degree to which these symbioses might impact local sulfur chemistry in situ. These experiments show that A) access to particular sulfur species differentially affects the productivity of vent symbioses, suggesting that competition for these substrates, both within and between host

Can high-temperature, high-heat flux hydrothermal vent fields be explained by thermal convection in the lower crust along fast-spreading Mid-Ocean Ridges?

NASA Astrophysics Data System (ADS)

Fontaine, Fabrice J.; Rabinowicz, M.; Cannat, M.

2017-05-01

We present numerical models to explore possible couplings along the axis of fast-spreading ridges, between hydrothermal convection in the upper crust and magmatic flow in the lower crust. In an end-member category of models corresponding to effective viscosities μM lower than 1013 Pa.s in a melt-rich lower crustal along-axis corridor and permeability k not exceeding ˜10-16 m2 in the upper crust, the hot, melt-rich, gabbroic lower crust convects as a viscous fluid, with convection rolls parallel to the ridge axis. In these models, we show that the magmatic-hydrothermal interface settles at realistic depths for fast ridges, i.e., 1-2 km below seafloor. Convection cells in both horizons are strongly coupled and kilometer-wide hydrothermal upflows/plumes, spaced by 8-10 km, arise on top of the magmatic upflows. Such magmatic-hydrothermal convective couplings may explain the distribution of vent fields along the East (EPR) and South-East Pacific Rise (SEPR). The lower crustal plumes deliver melt locally at the top of the magmatic horizon possibly explaining the observed distribution of melt-rich regions/pockets in the axial melt lenses of EPR and SEPR. Crystallization of this melt provides the necessary latent heat to sustain permanent ˜100 MW vents fields. Our models also contribute to current discussions on how the lower crust forms at fast ridges: they provide a possible mechanism for focused transport of melt-rich crystal mushes from moho level to the axial melt lens where they further crystallize, feed eruptions, and are transported both along and off-axis to produce the lower crust.

A Reactive-Transport Model Describing Methanogen Growth and Methane Production in Diffuse Flow Vents at Axial Seamount

NASA Astrophysics Data System (ADS)

Algar, C. K.

2015-12-01

Hydrogenotrophic methanogenesis is an important mode of metabolism in deep-sea hydrothermal vents. Diffuse vent fluids often show a depletion in hydrogen with a corresponding increase in methane relative to pure-mixing of end member fluid and seawater, and genomic surveys show an enrichment in genetic sequences associated with known methanogens. However, because we cannot directly sample the subseafloor habitat where these organisms are living, constraining the size and activity of these populations remains a challenge and limits our ability to quantify the role they play in vent biogeochemistry. Reactive-transport modeling may provide a useful tool for approaching this problem. Here we present a reactive-transport model describing methane production along the flow-path of hydrothermal fluid from its high temperature end-member to diffuse venting at the seafloor. The model is set up to reflect conditions at several diffuse vents in the Axial Seamount. The model describes the growth of the two dominant thermophilic methanogens, Methanothermococcus and Methanocaldococcus, observed at Axial seamount. Monod and Arrhenius constants for Methanothermococcus thermolithotrophicus and Methanocaldococcus jannaschii were obtained for the model using chemostat and bottle experiments at varying temperatures. The model is used to investigate the influence of different mixing regimes on the subseafloor populations of these methanogens. By varying the model flow path length and subseafloor cell concentrations, and fitting to observed hydrogen and methane concentrations in the venting fluid, the subseafloor biomass, fluid residence time, and methane production rate can be constrained.

Predicting the response of the deep-ocean microbiome to geochemical perturbations by hydrothermal vents.

PubMed

Reed, Daniel C; Breier, John A; Jiang, Houshuo; Anantharaman, Karthik; Klausmeier, Christopher A; Toner, Brandy M; Hancock, Cathrine; Speer, Kevin; Thurnherr, Andreas M; Dick, Gregory J

2015-08-01

Submarine hydrothermal vents perturb the deep-ocean microbiome by injecting reduced chemical species into the water column that act as an energy source for chemosynthetic organisms. These systems thus provide excellent natural laboratories for studying the response of microbial communities to shifts in marine geochemistry. The present study explores the processes that regulate coupled microbial-geochemical dynamics in hydrothermal plumes by means of a novel mathematical model, which combines thermodynamics, growth and reaction kinetics, and transport processes derived from a fluid dynamics model. Simulations of a plume located in the ABE vent field of the Lau basin were able to reproduce metagenomic observations well and demonstrated that the magnitude of primary production and rate of autotrophic growth are largely regulated by the energetics of metabolisms and the availability of electron donors, as opposed to kinetic parameters. Ambient seawater was the dominant source of microbes to the plume and sulphur oxidisers constituted almost 90% of the modelled community in the neutrally-buoyant plume. Data from drifters deployed in the region allowed the different time scales of metabolisms to be cast in a spatial context, which demonstrated spatial succession in the microbial community. While growth was shown to occur over distances of tens of kilometers, microbes persisted over hundreds of kilometers. Given that high-temperature hydrothermal systems are found less than 100 km apart on average, plumes may act as important vectors between different vent fields and other environments that are hospitable to similar organisms, such as oil spills and oxygen minimum zones.

Predicting the response of the deep-ocean microbiome to geochemical perturbations by hydrothermal vents

PubMed Central

Reed, Daniel C; Breier, John A; Jiang, Houshuo; Anantharaman, Karthik; Klausmeier, Christopher A; Toner, Brandy M; Hancock, Cathrine; Speer, Kevin; Thurnherr, Andreas M; Dick, Gregory J

2015-01-01

Submarine hydrothermal vents perturb the deep-ocean microbiome by injecting reduced chemical species into the water column that act as an energy source for chemosynthetic organisms. These systems thus provide excellent natural laboratories for studying the response of microbial communities to shifts in marine geochemistry. The present study explores the processes that regulate coupled microbial-geochemical dynamics in hydrothermal plumes by means of a novel mathematical model, which combines thermodynamics, growth and reaction kinetics, and transport processes derived from a fluid dynamics model. Simulations of a plume located in the ABE vent field of the Lau basin were able to reproduce metagenomic observations well and demonstrated that the magnitude of primary production and rate of autotrophic growth are largely regulated by the energetics of metabolisms and the availability of electron donors, as opposed to kinetic parameters. Ambient seawater was the dominant source of microbes to the plume and sulphur oxidisers constituted almost 90% of the modelled community in the neutrally-buoyant plume. Data from drifters deployed in the region allowed the different time scales of metabolisms to be cast in a spatial context, which demonstrated spatial succession in the microbial community. While growth was shown to occur over distances of tens of kilometers, microbes persisted over hundreds of kilometers. Given that high-temperature hydrothermal systems are found less than 100 km apart on average, plumes may act as important vectors between different vent fields and other environments that are hospitable to similar organisms, such as oil spills and oxygen minimum zones. PMID:25658053

Venting during prophylactic nailing for femoral metastases: current orthopedic practice.

PubMed

Dalgorf, Dustin; Borkhoff, Cornelia M; Stephen, David J G; Finkelstein, Joel; Kreder, Hans J

2003-12-01

Reamed intramedullary nailing, recommended for impending fracture of a femur weakened by bone metastases, causes a rise in intramedullary pressure and increases the risk of a fat embolism syndrome. The pressure can be equalized by the technique of venting--drilling a hole into the distal cortex of the femur. Our objective was to study the current practice of orthopedic surgeons in Ontario with respect to venting during prophylactic intramedullary nailing for an impending femoral fracture due to bone metastases. We mailed a questionnaire to all orthopedic surgeons from the Province of Ontario listed in the 1999 Canadian Medical Directory or on the Canadian Orthopaedic Association membership list, asking if they vent when prophylactically nailing an impending pathologic femoral fracture. The responses were modelled as a function of surgeon volume and year of graduation. Of the 415 surveys mailed, 223 (54%) surgeons responded. Of these, 81% reported having prophylactically treated a femoral metastatic lesion during the previous year; 67% treated 1 to 3 metastatic lesions and 14% treated more than 3; 19% did not treat a metastatic femoral lesion prophylactically. Over two-thirds of surgeons had never considered venting, whereas one-third always or sometimes vented the femoral canal. More recent graduates were 3 times more likely to vent than earlier (before 1980) graduates (odds ratio [OR] = 3.2, 95% confidence interval [CI] 1.6-6.5) as were those who treat a greater number of impending fractures (OR = 1.4, 95% CI 1.1-1.7). Although there is a theoretical rationale for routine venting, there is disagreement among Ontario orthopedic surgeons regarding the use of this technique during prophylactic nailing for femoral metastatic lesions. Prospective evidence will be required to warrant a change in the standard of care.

U-Th systematics and 230Th ages of carbonate chimneys at the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Ludwig, Kristin A.; Shen, Chuan-Chou; Kelley, Deborah S.; Cheng, Hai; Edwards, R. Lawrence

2011-04-01

The Lost City Hydrothermal Field (LCHF) is a serpentinite-hosted vent field located 15 km west of the spreading axis of the Mid-Atlantic Ridge. In this study, uranium-thorium (U-Th) geochronological techniques have been used to examine the U-Th systematics of hydrothermal fluids and the 230Th ages of hydrothermally-precipitated carbonate chimneys at the LCHF. Fluid sample analyses indicate that endmember fluids likely contain only 0.0073 ng/g U or less compared to 3.28 ± 0.03 ng/g of U in ambient seawater. For fluid samples containing only 2-21% ambient seawater (1.1-11 mmol/kg Mg), Th concentration is 0.11-0.13 pg/g and surrounding seawater concentrations average 0.133 ± 0.016 pg/g. The 230Th/ 232Th atomic ratios of the vent fluids range from 1 (±10) × 10 -6 to 11 (±5) × 10 -6, are less than those of seawater, and indicate that the vent fluids may contribute a minor amount of non-radiogenic 230Th to the LCHF carbonate chimney deposits. Chimney 238U concentrations range from 1 to 10 μg/g and the average chimney corrected initial δ 234U is 147.2 ± 0.8, which is not significantly different from the ambient seawater value of 146.5 ± 0.6. Carbonate 232Th concentrations range broadly from 0.0038 ± 0.0003 to 125 ± 16 ng/g and 230Th/ 232Th atomic ratios vary from near seawater values of 43 (±8) × 10 -6 up to 530 (±25) × 10 -3. Chimney ages, corrected for initial 230Th, range from 17 ± 6 yrs to 120 ± 13 kyrs. The youngest chimneys are at the intersection of two active, steeply-dipping normal faults that cut the Atlantis Massif; the oldest chimneys are located in the southwest portion of the field. Vent deposits on a steep, fault-bounded wall on the east side of the field are all <4 kyrs old, indicating that mass wasting in this region is relatively recent. Comparison of results to prior age-dating investigations of submarine hydrothermal systems shows that the LCHF is the most long-lived hydrothermal system known to date. It is likely that seismic

First hydrothermal discoveries on the Australian-Antarctic Ridge: Discharge sites, plume chemistry, and vent organisms

NASA Astrophysics Data System (ADS)

Hahm, Doshik; Baker, Edward T.; Siek Rhee, Tae; Won, Yong-Jin; Resing, Joseph A.; Lupton, John E.; Lee, Won-Kyung; Kim, Minjeong; Park, Sung-Hyun

2015-09-01

The Australian-Antarctic Ridge (AAR) is one of the largest unexplored regions of the global mid-ocean ridge system. Here, we report a multiyear effort to locate and characterize hydrothermal activity on two first-order segments of the AAR: KR1 and KR2. To locate vent sites on each segment, we used profiles collected by Miniature Autonomous Plume Recorders on rock corers during R/V Araon cruises in March and December of 2011. Optical and oxidation-reduction-potential anomalies indicate multiple active sites on both segments. Seven profiles on KR2 found 3 sites, each separated by ˜25 km. Forty profiles on KR1 identified 17 sites, some within a few kilometer of each other. The spatial density of hydrothermal activity along KR1 and KR2 (plume incidence of 0.34) is consistent with the global trend for a spreading rate of ˜70 mm/yr. The densest area of hydrothermal activity, named "Mujin," occurred along the 20 km-long inflated section near the segment center of KR1. Continuous plume surveys conducted in January-February of 2013 on R/V Araon found CH4/3He (1 - 15 × 106) and CH4/Mn (0.01-0.5) ratios in the plume samples, consistent with a basaltic-hosted system and typical of ridges with intermediate spreading rates. Additionally, some of the plume samples exhibited slightly higher ratios of H2/3He and Fe/Mn than others, suggesting that those plumes are supported by a younger hydrothermal system that may have experienced a recent eruption. The Mujin-field was populated by Kiwa crabs and seven-armed Paulasterias starfish previously recorded on the East Scotia Ridge, raising the possibility of circum-Antarctic biogeographic connections of vent fauna.

14 CFR 34.11 - Standard for fuel venting emissions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No fuel venting emissions shall be discharged into the atmosphere from any new or in-use aircraft gas... include one of the following: (1) Incorporation of an FAA-approved system that recirculates the fuel back...

14 CFR 34.11 - Standard for fuel venting emissions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No fuel venting emissions shall be discharged into the atmosphere from any new or in-use aircraft gas... include one of the following: (1) Incorporation of an FAA-approved system that recirculates the fuel back...

14 CFR 34.11 - Standard for fuel venting emissions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... Emissions (New and In-Use Aircraft Gas Turbine Engines) § 34.11 Standard for fuel venting emissions. (a) No fuel venting emissions shall be discharged into the atmosphere from any new or in-use aircraft gas... include one of the following: (1) Incorporation of an FAA-approved system that recirculates the fuel back...

Simulating a Submarine Hydrothermal Vent

NASA Image and Video Library

2013-01-16

A team of scientists at NASA Jet Propulsion Laboratory is testing whether organic molecules can be brewed in a simulated ocean vent. Pictured here is Lauren White, a member of the NASA Astrobiology Icy Worlds team.

Characterization of Chemosynthetic Microbial Mats Associated with Intertidal Hydrothermal Sulfur Vents in White Point, San Pedro, CA, USA

PubMed Central

Miranda, Priscilla J.; McLain, Nathan K.; Hatzenpichler, Roland; Orphan, Victoria J.; Dillon, Jesse G.

2016-01-01

The shallow-sea hydrothermal vents at White Point (WP) in Palos Verdes on the southern California coast support microbial mats and provide easily accessed settings in which to study chemolithoautotrophic sulfur cycling. Previous studies have cultured sulfur-oxidizing bacteria from the WP mats; however, almost nothing is known about the in situ diversity and activity of the microorganisms in these habitats. We studied the diversity, micron-scale spatial associations and metabolic activity of the mat community via sequence analysis of 16S rRNA and aprA genes, fluorescence in situ hybridization (FISH) microscopy and sulfate reduction rate (SRR) measurements. Sequence analysis revealed a diverse group of bacteria, dominated by sulfur cycling gamma-, epsilon-, and deltaproteobacterial lineages such as Marithrix, Sulfurovum, and Desulfuromusa. FISH microscopy suggests a close physical association between sulfur-oxidizing and sulfur-reducing genotypes, while radiotracer studies showed low, but detectable, SRR. Comparative 16S rRNA gene sequence analyses indicate the WP sulfur vent microbial mat community is similar, but distinct from other hydrothermal vent communities representing a range of biotopes and lithologic settings. These findings suggest a complete biological sulfur cycle is operating in the WP mat ecosystem mediated by diverse bacterial lineages, with some similarity with deep-sea hydrothermal vent communities. PMID:27512390

Characterizing Microbial Community and Geochemical Dynamics at Hydrothermal Vents Using Osmotically Driven Continuous Fluid Samplers

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

Robidart, Julie C.; Callister, Stephen J.; Song, Peng F.

2013-05-07

Microbes play a key role in mediating all aquatic biogeochemical cycles, and ongoing efforts are aimed at better understanding the relationships between microbial phylogenetic and physiological diversity, and habitat physical and chemical characteristics. Establishing such relationships is facilitated by sampling and studying microbiology and geochemistry at the appropriate spatial and temporal scales, to access information on the past and current environmental state that contributes to observed microbial abundances and activities. A modest number of sampling systems exist to date, few of which can be used in remote, harsh environments such as hydrothermal vents, where the ephemeral nature of venting underscoresmore » the necessity for higher resolution sampling. We have developed a robust, continuous fluid sampling system for co-registered microbial and biogeochemical analyses. The osmosis-powered bio-osmosampling system (BOSS) use no electricity, collects fluids with daily resolution or better, can be deployed in harsh, inaccessible environments and can sample fluids continuously for up to five years. Here we present a series of tests to examine DNA, RNA and protein stability over time, as well as material compatability, via lab experiments. We also conducted two field deployments at deep-sea hydrothermal vents to assess changes in microbial diversity and protein expression as a function of the physico-chemical environment. Our data reveal significant changes in microbial community composition co-occurring with relatively modest changes in the geochemistry. These data additionally provide new insights into the distribution of an enigmatic sulfur oxidizing symbiont in its free-living state. Data from the second deployment reveal differences in the representation of peptides over time, underscoring the utility of the BOSS in meta-proteomic studies. In concert, these data demonstrate the efficacy of this approach, and illustrate the value of using this method to

Zero Gravity Cryogenic Vent System Concepts for Upper Stages

NASA Technical Reports Server (NTRS)

Flachbart, Robin H.; Holt, James B.; Hastings, Leon J.

1999-01-01

The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. Venting without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy is required. a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point. the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating, boil-off losses.

U-Th isotopic systematics and ages of carbonate chimneys at the Lost City Hydrothermal Field

NASA Astrophysics Data System (ADS)

Ludwig, K. A.; Shen, C.; Kelley, D. S.; Cheng, H.; Edwards, R.

2009-12-01

The Lost City Hydrothermal Field (LCHF) is a serpentinite-hosted vent field located 15 km west of the spreading axis of the Mid-Atlantic Ridge. In this study, uranium-thorium (U-Th) geochronological techniques have been used to examine the U-Th isotopic systematics of hydrothermal fluids and the 230Th ages of hydrothermally-precipitated carbonate chimneys at the LCHF. Fluid sample analyses indicate that endmember fluids likely contain only 0.0073 ng/g U or less compared to 3.28 ± 0.03 ng/g of U in ambient seawater. For fluid samples with <15 mmol/kg Mg, 232Th concentration is 0.11 to 0.13 pg/g and surrounding seawater concentration average is 0.133 ± 0.016 pg/g. The 230Th/232Th atomic ratios of the vent fluids range from 1 ± 10 to 26 ± 4 ×10-6 and are less than those of seawater. Chimney U is seawater-derived and 238U concentrations range from 1-10 μg/g and the mean chimney corrected initial δ234U is 146.9 ± 0.5, which is not significantly different from the ambient seawater value of 146.5 ± 0.6. Carbonate thorium concentrations range broadly from 0.035-125 ng/g and 230Th/232Th atomic ratios vary from near seawater values of 43 ± 8 × 10-6 up to 530 ± 25 × 10-3. Chimney ages range from 18 ± 6 yrs to 122 ± 12 kyrs. The youngest chimneys are at the intersection of two active, steeply-dipping normal faults that cut the Atlantis Massif; the oldest chimneys are located in the southwest portion of the field. Vent deposits on a steep, fault-bounded wall on the east side of the field are all <4 kyrs old, indicating that mass wasting in this region is relatively recent. Comparison of results to prior age-dating investigations of submarine hydrothermal systems shows that the LCHF is the most long-lived hydrothermal system known to date. It is likely that seismic activity and active faulting within the Atlantis Massif and the Atlantis Fracture Zone, coupled with volumetric expansion of the underlying serpentinized host rocks play major roles in sustaining

Preliminary Results on Mineralogy and Geochemistry of Loki's Castle Arctic Vents and Host Sediments

NASA Astrophysics Data System (ADS)

Barriga, Fernando; Carvalho, Carlos; Inês Cruz, M.; Dias, Ágata; Fonseca, Rita; Relvas, Jorge; Pedersen, Rolf

2010-05-01

The Loki's Castle hydrothermal vent field was discovered in the summer of 2008, during a cruise led by the Centre of Geobiology of the University of Bergen, integrated in the H2Deep Project (Eurocores, ESF). Loki's Castle is the northernmost hydrothermal vent field discovered to date. It is located at the junction between the Mohns Ridge and the South Knipovich Ridge, in the Norwegian-Greenland Sea, at almost 74°N. This junction shows unique features and apparently there is no transform fault to accommodate the deformation generated by the bending of the rift valley from WSW-ENE to almost N-S. The Knipovich Rigde, being a complex structure, is an ultra-slow spreading ridge, with an effective spreading rate of only ~ 6 mm/y. It is partly masked by a substantial cover of glacial and post-glacial sediments, estimated to be between 12 and 20 ky old, derived from the nearby Bear Island fan, to the East of the ridge. The Loki's Castle vent site is composed of several active, over 10 m tall chimneys, producing up to 320°C fluid, at the top of a very large sulphide mound, which is estimated to be around 200 m in diameter. About a dozen gravity cores were obtained in the overall area. From these we collected nearly 200 subsamples. Eh and pH were measured in all subsamples. The Portuguese component of the H2Deep project is aimed at characterizing, chemically and mineralogically, the sulphide chimneys and the collected sediments around the vents (up to 5 meters long gravity cores). These studies are aimed at understanding the ore-forming system, and its implications for submarine mineral exploration, as well as the relation of the microbial population with the hydrothermal component of sediments. Here we present an overview of preliminary data on the mineralogical assemblage found in the analyzed sediments and chimneys. The identification of the different mineral phases was obtained through petrographic observations of polished thin sections under the microscope (with both

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

PubMed

Fortunato, Caroline S; Huber, Julie A

2016-08-01

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

Hydrothermal Activity on the Mid-Cayman Rise: ROV Jason sampling and site characterization at the Von Damm and Piccard hydrothermal fields

NASA Astrophysics Data System (ADS)

German, C. R.

2012-12-01

In January 2012 our multi-national and multi-disciplinary team conducted a series of 10 ROV Jason dives to conduct first detailed and systematic sampling of the Mid Cayman Rise hydrothermal systems at the Von Damm and Piccard hydrothermal fields. At Von Damm, hydrothermal venting is focused at and around a large conical structure that is approximately 120 m in diameter and rises at least 80m from the surrounding, largely sedimented seafloor. Clear fluids emitted from multiple sites around the flanks of the mound fall in the temperature range 110-130°C and fall on a common mixing line with hotter (>200°C) clear fluids emitted from an 8m tall spire at the summit which show clear evidence of ultramafic influence. Outcrop close to the vent-site is rare and the cone itself appear to consist of clay minerals derived from highly altered host rock. The dominant fauna at the summit of Von Damm are a new species of chemosynthetic shrimp but elsewhere the site also hosts two distinct species of chemosynthetic tube worm as well as at least one species of gastropod. The adjacent Piccard site, at ~5000m depth comprises 7 distinct sulfide mounds, 3 of which are currently active: Beebe Vents, Beebe Woods and Beebe Sea. Beebe Vents consists of 5 vigorous black smoker chimneys with maximum temperatures in the range 400-403°C while at Beebe Woods a more highly colonized thicket of up to 8m tall chimneys includes predominantly beehive diffusers with rare black smokers emitting fluids up to 353°C. Beebe Sea a diffuse site emitting fluids at 38°C Tmax, is the largest of the currently active mounds and immediately abuts a tall (8m) rift that strikes NE-SW bisecting the host Axial Volcanic Ridge. The fauna at Piccard are less diverse than at Von Damm and, predominantly, comprise the same species of MCR shrimp, a distinct gastropod species and abundant anemones.

Spatial scaling of bacterial community diversity at shallow hydrothermal vents: a global comparison

NASA Astrophysics Data System (ADS)

Pop Ristova, P.; Hassenrueck, C.; Molari, M.; Fink, A.; Bühring, S. I.

2016-02-01

Marine shallow hydrothermal vents are extreme environments, often characterized by discharge of fluids with e.g. high temperatures, low pH, and laden with elements toxic to higher organisms. They occur at continental margins around the world's oceans, but represent fragmented, isolated habitats of locally small areal coverage. Microorganisms contribute the main biomass at shallow hydrothermal vent ecosystems and build the basis of the food chain by autotrophic fixation of carbon both via chemosynthesis and photosynthesis, occurring simultaneously. Despite their importance and unique capacity to adapt to these extreme environments, little is known about the spatial scales on which the alpha- and beta-diversity of microbial communities vary at shallow vents, and how the geochemical habitat heterogeneity influences shallow vent biodiversity. Here for the first time we investigated the spatial scaling of microbial biodiversity patterns and their interconnectivity at geochemically diverse shallow vents on a global scale. This study presents data on the comparison of bacterial community structures on large (> 1000 km) and small (0.1 - 100 m) spatial scales as derived from ARISA and Illumina sequencing. Despite the fragmented global distribution of shallow hydrothermal vents, similarity of vent bacterial communities decreased with geographic distance, confirming the ubiquity of distance-decay relationship. Moreover, at all investigated vents, pH was the main factor locally structuring these communities, while temperature influenced both the alpha- and beta-diversity.

Longterm monitoring of pressure, tilt and temperature at Logatchev Hydrothermal Vent Field, Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Villinger, H. W.; Gennerich, H.-H.; Fabian, M.

2009-04-01

The geophysical parameters of pressure, tilt, acceleration and temperature at the Logatchev Hydrothermal Vent Field (LHF) which is located in 3050m water depth at about 15˚ N at the Mid-Atlantic Ridge, were monitored with high resolution for more than two and a half years, from May 2005 until December 2007. An autonomously operating Ocean Bottom Pressure Station (OBP; resolution of 80 Pa in the first year, improved to 8 Pa afterwards, sampling period of 2 minutes in the first year, increased to 2 seconds afterwards) and a programmable Ocean Bottom Tiltmeter (OBT; resolution 1 rad, sampling period 6 seconds) measured local ocean-floor point motions derived from tilt and absolute pressure. In addition, vertical acceleration was measured using a MEMS accelerometer (resolution 10-5 m/s2, sampling rate 1.33 Hz) within the housing of the OBT. Numerous autonomous temperature loggers (resolution 0.001˚ C, sampling period 15 minutes) were installed at prominent places like mussel fields or soil fissures within the LHF. Time series are analyzed using Fourier-Transformation techniques but also using the novel approach called Empirical Mode Decomposition (EMD). Pressure records show a modulated background noise level with increased amplitudes lasting for several days to weeks, and most likely show signals generated by local earthquakes. Bottom water temperature has transients with peak-to-peak-amplitudes of up to 0.1˚ C, which correlate for a number of events directly with earthquake signals. A comparison of pressure, tilt, acceleration and temperature data events shows that all four records are correlated. For a few of those events a direct causal link can be firmly established. The study is funded by the Deutsche Forschungsgemeinschaft (DFG) and part of Priority Program 1144 ("From Mantle to Ocean: Energy-, Material- and Life-cycles at Spreading Axes").

Response of key stress-related genes of the seagrass Posidonia oceanica in the vicinity of submarine volcanic vents

NASA Astrophysics Data System (ADS)

Lauritano, C.; Ruocco, M.; Dattolo, E.; Buia, M. C.; Silva, J.; Santos, R.; Olivé, I.; Costa, M. M.; Procaccini, G.

2015-07-01

Submarine volcanic vents are being used as natural laboratories to assess the effects of increased ocean acidity and carbon dioxide (CO2) concentration on marine organisms and communities. However, in the vicinity of volcanic vents other factors in addition to CO2, which is the main gaseous component of the emissions, may directly or indirectly confound the biota responses to high CO2. Here we used for the first time the expression of antioxidant and stress-related genes of the seagrass Posidonia oceanica to assess the stress levels of the species. Our hypothesis is that unknown factors are causing metabolic stress that may confound the putative effects attributed to CO2 enrichment only. We analyzed the expression of 35 antioxidant and stress-related genes of P. oceanica in the vicinity of submerged volcanic vents located in the islands of Ischia and Panarea, Italy, and compared them with those from control sites away from the influence of vents. Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) was used to characterize gene expression patterns. Fifty-one percent of genes analyzed showed significant expression changes. Metal detoxification genes were mostly down-regulated in relation to controls at both Ischia and Panarea, indicating that P. oceanica does not increase the synthesis of heavy metal detoxification proteins in response to the environmental conditions present at the two vents. The up-regulation of genes involved in the free radical detoxification response (e.g., CAPX, SODCP and GR) indicates that, in contrast with Ischia, P. oceanica at the Panarea site faces stressors that result in the production of reactive oxygen species, triggering antioxidant responses. In addition, heat shock proteins were also activated at Panarea and not at Ischia. These proteins are activated to adjust stress-accumulated misfolded proteins and prevent their aggregation as a response to some stressors, not necessarily high temperature. This is the first

RNA Oligomerization in Laboratory Analogues of Alkaline Hydrothermal Vent Systems.

PubMed

Burcar, Bradley T; Barge, Laura M; Trail, Dustin; Watson, E Bruce; Russell, Michael J; McGown, Linda B

2015-07-01

Discovering pathways leading to long-chain RNA formation under feasible prebiotic conditions is an essential step toward demonstrating the viability of the RNA World hypothesis. Intensive research efforts have provided evidence of RNA oligomerization by using circular ribonucleotides, imidazole-activated ribonucleotides with montmorillonite catalyst, and ribonucleotides in the presence of lipids. Additionally, mineral surfaces such as borates, apatite, and calcite have been shown to catalyze the formation of small organic compounds from inorganic precursors (Cleaves, 2008 ), pointing to possible geological sites for the origins of life. Indeed, the catalytic properties of these particular minerals provide compelling evidence for alkaline hydrothermal vents as a potential site for the origins of life since, at these vents, large metal-rich chimney structures can form that have been shown to be energetically favorable to diverse forms of life. Here, we test the ability of iron- and sulfur-rich chimneys to support RNA oligomerization reactions using imidazole-activated and non-activated ribonucleotides. The chimneys were synthesized in the laboratory in aqueous "ocean" solutions under conditions consistent with current understanding of early Earth. Effects of elemental composition, pH, inclusion of catalytic montmorillonite clay, doping of chimneys with small organic compounds, and in situ ribonucleotide activation on RNA polymerization were investigated. These experiments, under certain conditions, showed successful dimerization by using unmodified ribonucleotides, with the generation of RNA oligomers up to 4 units in length when imidazole-activated ribonucleotides were used instead. Elemental analysis of the chimney precipitates and the reaction solutions showed that most of the metal cations that were determined were preferentially partitioned into the chimneys.

Occurrence and structural characterization of gas hydrates associated with a cold vent field, offshore Vancouver Island

NASA Astrophysics Data System (ADS)

Lu, Hailong; Moudrakovski, Igor; Riedel, Michael; Spence, George; Dutrisac, Regent; Ripmeester, John; Wright, Fred; Dallimore, Scott

2005-10-01

Gas hydrate samples recovered from a cold vent field offshore Vancouver Island were studied in detail both by macroscopic observations and instrumental methods (powder X-ray diffraction method (PXRD), nuclear magnetic resonance (NMR), and Raman spectroscopy). It was found that gas hydrates were massive from 2.64 to 2.94 m below seafloor (mbsf), elongated, nodular and tabular from 4.60 to 4.81 mbsf, and vein-like from 5.48 to 5.68 mbsf, showing a trend of decreasing hydrate content with increasing depth. All samples were determined to be structure I hydrate from PXRD, NMR, and Raman spectroscopies. The hydration numbers were estimated to be 6.1 ± 0.2 on average as determined from the methane distribution over the cage sites from NMR and Raman analytical results. Estimates of conversion levels indicated that ˜78% of the water in the massive samples was hydrate, down to a low value of ˜0.4% for the pore hydrate samples. The results are compared with measurements on synthetic hydrates and samples recovered from below the permafrost on the Mallik site. Differences in methane content and lattice parameters for synthetic and natural samples are relatively minor. Additional work is needed to address the presence of minor gas components and the heterogeneity of natural hydrate samples.

Vent modification of large ribbon parachutes to enhance cluster performance

NASA Technical Reports Server (NTRS)

Kolega, D. J.; Woodis, W. R.; Reuter, J. D.

1986-01-01

Due to uneven load sharing and lagging inflation rates, the design of the Large Main Parachute (LMP) cluster, used to recover the Space Shuttle steel case Solid Rocket Boosters, had to be modified. The cause of the problem was excessive variation in effective porosity in the crown area of the LMP during first stage inflation. The design modification consisted of adding horizontal ribbons above the existing vent band to reduce the vent porosity and better control the position and attitude of the vent lines. Performance of modified LMP's since introduction indicates that the load sharing between the clustered chutes has been significantly improved.

Visualization of the air flow behind the automotive benchmark vent

NASA Astrophysics Data System (ADS)

Pech, Ondrej; Jedelsky, Jan; Caletka, Petr; Jicha, Miroslav

2015-05-01

Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the flow behind the ventilation outlet. The article deals with the visualization of air flow from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of air flow axis were investigated.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents

USGS Publications Warehouse

Taylor, Vivien F.; Jackson, Brian P.; Siegfried, Matthew R.; Navratilova, Jana; Francesconi, Kevin A.; Kirshtein, Julie; Voytek, Mary

2012-01-01

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata, the vent chimney-dwelling mussel, Bathymodiolus azoricus, Branchipolynoe seepensis, a commensal worm of B. azoricus and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ13C and δ15N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata, whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a foodweb without algae or other photosynthetic life.

Arsenic speciation in food chains from mid-Atlantic hydrothermal vents.

PubMed

Taylor, Vivien F; Jackson, Brian P; Siegfried, Matthew; Navratilova, Jana; Francesconi, Kevin A; Kirshtein, Julie; Voytek, Mary

2012-05-04

Arsenic concentration and speciation were determined in benthic fauna collected from the Mid-Atlantic Ridge hydrothermal vents. The shrimp species, Rimicaris exoculata , the vent chimney-dwelling mussel, Bathymodiolus azoricus , Branchipolynoe seepensis , a commensal worm of B. azoricus , and the gastropod Peltospira smaragdina showed variations in As concentration and in stable isotope (δ 13 C and δ 15 N) signature between species, suggesting different sources of As uptake. Arsenic speciation showed arsenobetaine to be the dominant species in R. exoculata , whereas in B. azoricus and B. seepensis arsenosugars were most abundant, although arsenobetaine, dimethylarsinate, and inorganic arsenic were also observed, along with several unidentified species. Scrape samples from outside the vent chimneys, covered with microbial mat, which is a presumed food source for many vent organisms, contained high levels of total As, but organic species were not detectable. The formation of arsenosugars in pelagic environments is typically attributed to marine algae, and the pathway to arsenobetaine is still unknown. The occurrence of arsenosugars and arsenobetaine in these deep sea organisms, where primary production is chemolithoautotrophic and stable isotope analyses indicate food sources are of vent origin, suggests that organic arsenicals can occur in a food web without algae or other photosynthetic life.

Fluid geochemistry of cold seeps and hydrothermal vents in the Guaymas Basin, Gulf of California

NASA Astrophysics Data System (ADS)

Hensen, Christian; Geilert, Sonja; Scholz, Florian; Schmidt, Mark; Liebetrau, Volker; Kipfer, Rolf; Sarkar, Sudipta; Doll, Mechthild

2017-04-01

In this study, we present geochemical data from pore fluids and gases that were sampled at cold seeps and hydrothermal vents in the Guaymas Basin during Sonne cruise 241. The Guaymas Basin is a unique environment where magma intrudes into thick sequences of organic-rich sediments, thereby maturing host rocks and releasing large amounts of hydrocarbons. Geochemical measurements performed on samples from a recently discovered high-temperature vent field (Berndt et al., 2016) clearly support this paradigm. 3He/4He ratios agree with that of excess He from the southern part of the Guaymas Basin (Lupton, 1979) and suggest the same general MORB source, while isotopic data of hydrocarbon gases largely indicate a thermogenic, sedimentary source. Heat flow measurements performed in the vicinity of the smoker site are extremely high, exceeding 10 W/m2, indicating that hydrocarbon gas production (mainly CH4) is related to contact heating due to magmatic activity near the hydrothermal vents. Cold seeps are located up to some tens of kilometres off the rift axis and are typically characterized by chemosynthetic fauna assemblages at the seafloor. The occurrence of the seeps has also been related to sill intrusions. Seismic records typically show evidence for sediment mobilization in the deeper subsurface and blanked zones due to gas accumulations directly beneath the seeps. Despite these visual and geophysical indications for deep-sourced heat-driven fluid flow, pore water data are not indicative for geochemical reactions taking place at elevated temperatures. Major dissolved constituents do not show strong deviations from seawater and dissolved methane is typically of biogenic origin. In addition, heat flow values do not deviate from regional averages, and hence, these findings contradict the existing hypothesis of a sill-driven mechanism responsible for the formation of seafloor seepage sites. A preliminary interpretation is that fluid and gas mobilisation from sill activity

Population subdivision of hydrothermal vent polychaete Alvinella pompejana across equatorial and Easter Microplate boundaries.

PubMed

Jang, Sook-Jin; Park, Eunji; Lee, Won-Kyung; Johnson, Shannon B; Vrijenhoek, Robert C; Won, Yong-Jin

2016-10-28

The Equator and Easter Microplate regions of the eastern Pacific Ocean exhibit geomorphological and hydrological features that create barriers to dispersal for a number of animals associated with deep-sea hydrothermal vent habitats. This study examined effects of these boundaries on geographical subdivision of the vent polychaete Alvinella pompejana. DNA sequences from one mitochondrial and eleven nuclear genes were examined in samples collected from ten vent localities that comprise the species' known range from 23°N latitude on the East Pacific Rise to 38°S latitude on the Pacific Antarctic Ridge. Multi-locus genotypes inferred from these sequences clustered the individual worms into three metapopulation segments - the northern East Pacific Rise (NEPR), southern East Pacific Rise (SEPR), and northeastern Pacific Antarctic Ridge (PAR) - separated by the Equator and Easter Microplate boundaries. Genetic diversity estimators were negatively correlated with tectonic spreading rates. Application of the isolation-with-migration (IMa2) model provided information about divergence times and demographic parameters. The PAR and NEPR metapopulation segments were estimated to have split roughly 4.20 million years ago (Mya) (2.42-33.42 Mya, 95 % highest posterior density, (HPD)), followed by splitting of the SEPR and NEPR segments about 0.79 Mya (0.07-6.67 Mya, 95 % HPD). Estimates of gene flow between the neighboring regions were mostly low (2 Nm < 1). Estimates of effective population size decreased with southern latitudes: NEPR > SEPR > PAR. Highly effective dispersal capabilities allow A. pompejana to overcome the temporal instability and intermittent distribution of active hydrothermal vents in the eastern Pacific Ocean. Consequently, the species exhibits very high levels of genetic diversity compared with many co-distributed vent annelids and mollusks. Nonetheless, its levels of genetic diversity in partially isolated populations are inversely

Toward an integrated genetic model for vent-distal SEDEX deposits

NASA Astrophysics Data System (ADS)

Sangster, D. F.

2018-04-01

Although genetic models have been proposed for vent-proximal SEDEX deposits, an equivalent model for vent-distal deposits has not yet appeared. In view of this, it is the object of this paper to present a preliminary integrated vent-distal genetic model through exploration of four major components: (i) nature of the ore-forming fluid, (ii) role of density of the unconsolidated host sediments, (iii) dynamics of sulfate reduction and (iv) depositional environment. Two sub-groups of SEDEX Pb-Zn deposits, vent-proximal and vent-distal, are widely recognized today. Of the two, the latter is by far the largest in terms of metal content with each of the 13 largest containing in excess of 7.5 M (Zn+Pb) metal. In contrast, only one vent-proximal deposit (Sullivan) falls within this size range. Vent-proximal deposits are characteristically underlain by local networks of sulfide-filled veins (commonly regarded as feeder veins) surrounded by a discordant complex of host rock alteration. These attributes are missing in vent-distal deposits, which has led to the widespread view that vent-distal ore-forming fluids have migrated unknown distances away from their vent sites. Because of the characteristic fine grain size of ore minerals, critical fluid inclusion data are lacking for vent-distal ore-stage sulfides. Consequently, hypothetical fluids such as those which formed MVT deposits (120 °C, 20% NaCl equiv.) are considered to represent vent-distal fluids as well. Such high-salinity fluids are capable of carrying significant concentrations of Pb and Zn as chloride complexes while the relatively low temperatures preclude high Cu contents. Densities of such metalliferous brines result in bottom-hugging fluids that collect in shallow saucer-shaped depressions (collector basins). Lateral metal zoning in several deposits reveals the direction from which the brines came. Relative densities of the ore-forming fluid and sediment determine whether the ore-forming fluid stabilizes on top

Bus Vent Design Evolution for the Solar Dynamics Observatory

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2010-01-01

As a spacecraft undergoes ascent in a launch vehicle, its pressure environment transitions from one atmosphere to high vacuum in a matter of minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. Opposing the need to vent these volumes freely into space are thermal, optical, and electrostatic requirements for limiting or prohibiting the intrusion of unwanted energy into the same cavities. Bus vent design evolution is discussed for the Solar Dynamics Observatory. Design changes were influenced by a number of factors and concerns, such as contamination control, electrostatic discharge, changes in bus material, and driving fairing ascent pressure for a launch vehicle that was just entering service as this satellite project had gotten underway.

40 CFR 63.1322 - Batch process vents-reference control technology.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Batch process vents-reference control technology. 63.1322 Section 63.1322 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Batch process vents—reference control technology. (a) Batch process vents. The owner or operator of a...

40 CFR 63.113 - Process vent provisions-reference control technology.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1...

40 CFR 63.1322 - Batch process vents-reference control technology.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 12 2013-07-01 2013-07-01 false Batch process vents-reference control... (CONTINUED) National Emission Standards for Hazardous Air Pollutant Emissions: Group IV Polymers and Resins § 63.1322 Batch process vents—reference control technology. (a) Batch process vents. The owner or...

40 CFR 63.113 - Process vent provisions-reference control technology.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 10 2012-07-01 2012-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1...

40 CFR 63.113 - Process vent provisions-reference control technology.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 10 2013-07-01 2013-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1...

40 CFR 63.113 - Process vent provisions-reference control technology.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 9 2011-07-01 2011-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1...

40 CFR 63.113 - Process vent provisions-reference control technology.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 10 2014-07-01 2014-07-01 false Process vent provisions-reference control technology. 63.113 Section 63.113 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 63.113 Process vent provisions—reference control technology. (a) The owner or operator of a Group 1...

40 CFR 63.1322 - Batch process vents-reference control technology.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 12 2012-07-01 2011-07-01 true Batch process vents-reference control technology. 63.1322 Section 63.1322 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Batch process vents—reference control technology. (a) Batch process vents. The owner or operator of a...

40 CFR 63.1322 - Batch process vents-reference control technology.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Batch process vents-reference control technology. 63.1322 Section 63.1322 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... § 63.1322 Batch process vents—reference control technology. (a) Batch process vents. The owner or...

40 CFR 63.1322 - Batch process vents-reference control technology.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Batch process vents-reference control technology. 63.1322 Section 63.1322 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Batch process vents—reference control technology. (a) Batch process vents. The owner or operator of a...

Optimizing the night time with dome vents and SNR-QSO at CFHT

NASA Astrophysics Data System (ADS)

Devost, Daniel; Mahoney, Billy; Moutou, Claire; CFHT QSO Team, CFHT software Group

2017-06-01

Night time is a precious and costly commodity and it is important to get everything we can out of every second of every night of observing. In 2012 the Canada-France-Hawaii Telescope started operating 12 new vent doors installed on the dome over the course of the previous two years. The project was highly successful and seeing measurements show that venting the dome greatly enhances image quality at the focal plane. In order to capitalize on the gains brought by the new vents, the observatory started exploring a new mode of observation called SNR-QSO. This mode consist of a new implementation inside our Queued Service Observation (QSO) system. Exposure times are adjusted for each frame depending on the weather conditions in order to reach a specific depth, Signal to Noise Ratio (SNR) at a certain magnitude. The goal of this new mode is to capitalize on the exquisite seeing provided by Maunakea, complemented by the minimized dome turbulence, to use the least amount of time to reach the depth required by the science programs. Specific implementations were successfully tested on two different instruments, our wide field camera MegaCam and our high resolution spectrograph ESPaDOnS. I will present the methods used for each instrument to achieve SNR observing and the gains produced by these new observing modes in order to reach the scientific goals of accepted programs in a shorter amount of time.

Development and relationship of monogenetic and polygenetic volcanic fields in time and space.

NASA Astrophysics Data System (ADS)

Germa, Aurelie; Connor, Chuck; Connor, Laura; Malservisi, Rocco

2013-04-01

The classification of volcanic systems, developed by G. P. L. Walker and colleagues, relates volcano morphology to magma transport and eruption processes. In general, distributed monogenetic volcanic fields are characterized by infrequent eruptions, low average output rate, and a low spatial intensity of the eruptive vents. In contrast, central-vent-dominated systems, such as stratovolcanoes, central volcanoes and lava shields are characterized by frequent eruptions, higher average flux rates, and higher spatial intensity of eruptive vents. However, it has been observed that a stratovolcano is often associated to parasitic monogenetic vents on its flanks, related to the central silicic systems, and surrounded by an apron of monogenetic edifices that are part of the volcanic field but independent from the principal central system. It appears from spatial distribution and time-volume relationships that surface area of monogenetic fields reflects the lateral extent of the magma source region and the lack of magma focusing mechanisms. In contrast, magma is focused through a unique conduit system for polygenetic volcanoes, provided by a thermally and mechanically favorable pathway toward the surface that is maintained by frequent and favorable stress conditions. We plan to relate surface observations of spatio-temporal location of eruptive vents and evolution of the field area through time to processes that control magma focusing during ascent and storage in the crust. We choose to study fields that range from dispersed to central-vent dominated, through transitional fields (central felsic system with peripheral field of monogenetic vents independent from the rhyolitic system). We investigate different well-studied volcanic fields in the Western US and Western Europe in order to assess influence of the geodynamic setting and tectonic stress on the spatial distribution of magmatism. In summary, incremental spatial intensity maps should reveal how fast a central conduit

Vented Cavity Radiant Barrier Assembly And Method

DOEpatents

Dinwoodie, Thomas L.; Jackaway, Adam D.

2000-05-16

A vented cavity radiant barrier assembly (2) includes a barrier (12), typically a PV module, having inner and outer surfaces (18, 22). A support assembly (14) is secured to the barrier and extends inwardly from the inner surface of the barrier to a building surface (14) creating a vented cavity (24) between the building surface and the barrier inner surface. A low emissivity element (20) is mounted at or between the building surface and the barrier inner surface. At least part of the cavity exit (30) is higher than the cavity entrance (28) to promote cooling air flow through the cavity.

Bacterial and archaeal communities in the deep-sea sediments of inactive hydrothermal vents in the Southwest India Ridge

NASA Astrophysics Data System (ADS)

Zhang, Likui; Kang, Manyu; Xu, Jiajun; Xu, Jian; Shuai, Yinjie; Zhou, Xiaojian; Yang, Zhihui; Ma, Kesen

2016-05-01

Active deep-sea hydrothermal vents harbor abundant thermophilic and hyperthermophilic microorganisms. However, microbial communities in inactive hydrothermal vents have not been well documented. Here, we investigated bacterial and archaeal communities in the two deep-sea sediments (named as TVG4 and TVG11) collected from inactive hydrothermal vents in the Southwest India Ridge using the high-throughput sequencing technology of Illumina MiSeq2500 platform. Based on the V4 region of 16S rRNA gene, sequence analysis showed that bacterial communities in the two samples were dominated by Proteobacteria, followed by Bacteroidetes, Actinobacteria and Firmicutes. Furthermore, archaeal communities in the two samples were dominated by Thaumarchaeota and Euryarchaeota. Comparative analysis showed that (i) TVG4 displayed the higher bacterial richness and lower archaeal richness than TVG11; (ii) the two samples had more divergence in archaeal communities than bacterial communities. Bacteria and archaea that are potentially associated with nitrogen, sulfur metal and methane cycling were detected in the two samples. Overall, we first provided a comparative picture of bacterial and archaeal communities and revealed their potentially ecological roles in the deep-sea environments of inactive hydrothermal vents in the Southwest Indian Ridge, augmenting microbial communities in inactive hydrothermal vents.

Hydrogen may be an energy source for endosymbiotic bacteria of the vent mussel Bathymodiolus puteoserpentis

NASA Astrophysics Data System (ADS)

Zielinski, F.; Pape, T.; Wenzhöfer, F.; Seifert, R.; Dubilier, N.

2005-12-01

The ultramafic hosted Logatchev hydrothermal vent field at the slow spreading Mid-Atlantic Ridge (MAR) exhibits unusually high hydrogen concentrations due to serpentinization of ultramafic rocks. Endmember H2-concentrations here have been calculated to be as high as 12 mM which is significantly higher than at most other vent sites along the MAR. Hydrogen is a potential energy source for bacteria providing an energy yield of roughly 240 kJ/mol if oxidized with oxygen. Hence, the energy yield is even higher than for conventional aerobic respiration which liberates 220 kJ/mol. The ability to use H2 as an energy source has been shown for a variety of free-living bacteria. However, to date no other energy sources besides methane and sulfide have been identified for vent (or seep) symbionts. Here we show that H2 is consumed by endosymbiotic bacteria of the Logatchev vent mussel Bathymodiolus puteoserpentis. B. puteoserpentis is known to live in dual symbiosis with methane- and sulfide-oxidizing bacteria that occur intracellularly in specialized gill cells called bacteriocytes. The methanotrophic symbionts use methane as both an energy and carbon source whereas the thiotrophic symbionts use H2S as an energy and dissolved CO2 as a carbon source. Hydrothermal fluids carrying methane and sulfide provide the energy for the bacteria and the bacteria in turn provide the mussel with carbon compounds. The mussel on the other hand supplies its symbionts with a constant fluid flow and, by hosting them offers an ideal ecological niche. Freshly dissected gill pieces of B. puteoserpentis incubated in chilled sea water containing hydrogen gas readily consumed H2. The consumption of H2 over time was significantly higher in gill tissues than in symbiont-free mussel tissue indicating that the symbiotic bacteria are responsible for the observed activity. H2-consumption rates were similar in mussels from two different sampling sites, Irina II: 37 nmol h-1 (ml gill)-1 and Quest: 31 nmol h-1

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 12 2014-07-01 2014-07-01 false Glycol dehydration unit process vent... Storage Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 12 2013-07-01 2013-07-01 false Glycol dehydration unit process vent... Storage Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as...

10 CFR 50.46a - Acceptance criteria for reactor coolant system venting systems.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Acceptance criteria for reactor coolant system venting... criteria for reactor coolant system venting systems. Each nuclear power reactor must be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required...

10 CFR 50.46a - Acceptance criteria for reactor coolant system venting systems.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Acceptance criteria for reactor coolant system venting... criteria for reactor coolant system venting systems. Each nuclear power reactor must be provided with high point vents for the reactor coolant system, for the reactor vessel head, and for other systems required...

Characteristics of the cultivable bacteria from sediments associated with two deep-sea hydrothermal vents in Okinawa Trough.

PubMed

Sun, Qing-lei; Wang, Ming-qing; Sun, Li

2015-12-01

In this study, different culture-dependent methods were used to examine the cultivable heterotrophic bacteria in the sediments associated with two deep-sea hydrothermal vents (named HV1 and HV2) located at Iheya Ridge and Iheya North in Okinawa Trough. The two vents differed in morphology, with HV1 exhibiting diffuse flows while HV2 being a black smoker with a chimney-like structure. A total of 213 isolates were identified by near full-length 16S rRNA gene sequence analysis. Of these isolates, 128 were from HV1 and 85 were from HV2. The bacterial community structures were, in large parts, similar between HV1 and HV2. Nevertheless, differences between HV1 and HV2 were observed in one phylum, one class, 4 orders, 10 families, and 20 genera. Bioactivity analysis revealed that 25 isolates belonging to 9 different genera exhibited extracellular protease activities, 21 isolates from 11 genera exhibited extracellular lipase activities, and 13 isolates of 8 genera displayed antimicrobial activities. This is the first observation of a large population of bacteria with extracellular bioactivities existing in deep-sea hydrothermal vents. Taken together, the results of this study provide new insights into the characteristics of the cultivable heterotrophic bacteria in deep-sea hydrothermal ecosystems.

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 12 2012-07-01 2011-07-01 true Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 11 2010-07-01 2010-07-01 true Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 11 2013-07-01 2013-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as specified in either...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 10 2011-07-01 2011-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 11 2014-07-01 2014-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart that must be controlled for air emissions as specified in either...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 10 2010-07-01 2010-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.1275 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 11 2011-07-01 2011-07-01 false Glycol dehydration unit process vent... Facilities § 63.1275 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

40 CFR 63.765 - Glycol dehydration unit process vent standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 11 2012-07-01 2012-07-01 false Glycol dehydration unit process vent... Facilities § 63.765 Glycol dehydration unit process vent standards. (a) This section applies to each glycol dehydration unit subject to this subpart with an actual annual average natural gas flowrate equal to or...

Impact of vent pipe diameter on characteristics of waste degradation in semi-aerobic bioreactor landfill.

PubMed

Jiang, Guobin; Liu, Dan; Chen, Weiming; Ye, Zhicheng; Liu, Hong; Li, Qibin

2017-10-01

The evolution mechanism of a vent pipe diameter on a waste-stabilization process in semi-aerobic bioreactor landfills was analyzed from the organic-matter concentration, biodegradability, spectral characteristics of dissolved organic matter, correlations and principal-component analysis. Waste samples were collected at different distances from the vent pipe and from different landfill layers in semi-aerobic bioreactor landfills with different vent pipe diameters. An increase in vent pipe diameter favored waste degradation. Waste degradation in landfills can be promoted slightly when the vent pipe diameter increases from 25 to 50 mm. It could be promoted significantly when the vent pipe diameter was increased to 75 mm. The vent pipe diameter is important in waste degradation in the middle layer of landfills. The dissolved organic matter in the waste is composed mainly of long-wave humus (humin), short-wave humus (fulvic acid) and tryptophan. The humification levels of the waste that was located at the center of vent pipes with 25-, 50- and 75-mm diameters were 2.2682, 4.0520 and 7.6419 Raman units, respectively. The appropriate vent pipe diameter for semi-aerobic bioreactor landfills with an 800-mm diameter was 75 mm. The effect of different vent pipe diameters on the degree of waste stabilization is reflected by two main components. Component 1 is related mainly to the content of fulvic acid, biologically degradable material and organic matter. Component 2 is related mainly to the content of tryptophan and humin from the higher vascular plants.

Environmental controls on chemoautotrophic primary producers at deep-sea vents

NASA Astrophysics Data System (ADS)

Le Bris, Nadine; Mullineaux, Lauren; Sievert, Stefan

2014-05-01

High biomasses and fast growth rates of dominant chemosynthetic species characterize hydrothermal ecosystems, raising the issue of their contribution to energy transfer and carbon cycling in the deep-sea. Addressing this issue, however, needs to account for the temporal instability of hydrothermal systems, both, in terms of biological colonization and habitat conditions. Volcanic eruptions on mid-ocean ridges offer the opportunity to investigate the environmental conditions favoring the successive modes of chemoautotrophic primary production (i.e. free living microbes and symbiotic invertebrates). In that perspective, habitat-scale approaches distinguish from vent field-scale approaches based on fluid composition and provide relevant information on environmental constraints exerted at different stages of colonization focusing on parameters linked with physiological limits and available energy. Investigation of habitat physicochemical properties along a typical successional sequence of recolonization at 9°50'N EPR diffuse-flow vents, between 2006 and 2014, was performed in order to examine potential changes in environmental features associated with chemoautotrophic primary producers, from early microbial colonizers to symbiotic invertebrates. Combined in situ measurements of temperature, pH and hydrogen sulfide were used and their variability documented over a series of assemblages characterizing recolonization stages. The distributions of mature assemblages of dominant invertebrate species associate with substantial differences in habitat conditions, pointing to a strong influence of habitat properties on potential productivity. Among the differences observed, however, the amplitude and rate of environmental fluctuation appear more important than average conditions in the succession, highlighting the role of spatial heterogeneity and temporal dynamics as a control on primary producers. Invertebrate species acting as engineer species are expected to play a primary

40 CFR 63.644 - Monitoring provisions for miscellaneous process vents.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) of this section, each owner or operator of a Group 1 miscellaneous process vent that uses a... detecting the presence of a pilot flame is required. (3) Any boiler or process heater with a design heat... less than 44 megawatts design heat capacity where the vent stream is not introduced into the flame zone...

40 CFR 63.644 - Monitoring provisions for miscellaneous process vents.

Code of Federal Regulations, 2011 CFR

2011-07-01

...) of this section, each owner or operator of a Group 1 miscellaneous process vent that uses a... detecting the presence of a pilot flame is required. (3) Any boiler or process heater with a design heat... less than 44 megawatts design heat capacity where the vent stream is not introduced into the flame zone...

Model for the Evolution of an Oceanic Core Complex and its Hydrothermal Vent on the Ultraslow-Spreading Mid Cayman Spreading Center

NASA Astrophysics Data System (ADS)

Harding, J.; Van Avendonk, H. J.; Hayman, N. W.; Grevemeyer, I.; Peirce, C.

2016-12-01

The Mid Cayman Spreading Center (MCSC) is an ultraslow-spreading center (15 mm yr-1 full rate) along the Caribbean-North American plate boundary. Despite the paradigm that ultraslow-spreading centers are amagmatic and cold, two hydrothermal vent fields have recently been discovered along the MCSC. The Beebe Vent Field is a black smoker in the northern axial deep, and the Von Damm Vent Field (VDVF) is a moderate-temperature, talc precipitating vent found atop an oceanic core complex (OCC). This OCC, "Mt. Dent", is a large (3 km high) massif that formed beneath a detachment fault, which exhumed lower crustal and upper mantle material. The CaySeis Experiment was conducted in April, 2015 in order to collect wide-angle refraction data of the MCSC crust and upper mantle. We modeled the across-axis crustal structure of Mt. Dent as well as the surrounding lithosphere using 2.5D P-wave tomography. Using this tomographic model, along with geochemistry, we propose a model for the formation and evolution of the OCC Mt. Dent and the VDVF. A detachment fault formed in a magma-poor environment due to a pulse of magmatism, producing a large gabbro body that was then exhumed and rotated into the OCC footwall. Once magmatism waned and the gabbroic body cooled, the OCC was faulted and fractured due to plate flexure and increased tectonic extensional stress in the naturally cold and thick lithosphere. These faults provide a permeable and deep network of hydrothermal pathways that mine deep lithospheric heat and expose gabbro and fresh mantle peridotite. This model is consistent with the basalt geochemistry, hydrothermal fluid geochemistry, and the distribution of brittle vs. ductile structures along the detachment shear zone. The VDVF is therefore a product of a pulse of magmatism in an overall melt-poor environment, conditions that may be found at other ultraslow-spreading ridges.

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.

Exploratory Investigation of Aerodynamic Characteristics of Helicopter Tail Boom Cross-Section Models with Passive Venting

NASA Technical Reports Server (NTRS)

Banks, Daniel W.; Kelley, Henry L.

2000-01-01

Two large-scale, two-dimensional helicopter tail boom models were used to determine the effects of passive venting on boom down loads and side forces in hovering crosswind conditions. The models were oval shaped and trapezoidal shaped. Completely porous and solid configurations, partial venting in various symmetric and asymmetric configurations, and strakes were tested. Calculations were made to evaluate the trends of venting and strakes on power required when applied to a UH-60 class helicopter. Compared with the UH-60 baseline, passive venting reduced side force but increased down load at flow conditions representing right sideward flight. Selective asymmetric venting resulted in side force benefits close to the fully porous case. Calculated trends on the effects of venting on power required indicated that the high asymmetric oval configuration was the most effective venting configuration for side force reduction, and the high asymmetric with a single strake was the most effective for overall power reduction. Also, curves of side force versus flow angle were noticeable smoother for the vented configurations compared with the solid baseline configuration; this indicated a potential for smoother flight in low-speed crosswind conditions.

Community Structure of Macrobiota and Environmental Parameters in Shallow Water Hydrothermal Vents off Kueishan Island, Taiwan

PubMed Central

Chan, Benny Kwok Kan; Wang, Teng-Wei; Chen, Pin-Chen; Lin, Chia-Wei; Chan, Tin-Yam; Tsang, Ling Ming

2016-01-01

Hydrothermal vents represent a unique habitat in the marine ecosystem characterized with high water temperature and toxic acidic chemistry. Vents are distributed at depths ranging from a few meters to several thousand meters. The biological communities of shallow-water vents have, however, been insufficiently studied in most biogeographic areas. We attempted to characterize the macrofauna and macroflora community inhabiting the shallow-water vents off Kueishan Island, Taiwan, to identify the main abiotic factors shaping the community structure and the species distribution. We determined that positively buoyant vent fluid exhibits a more pronounced negative impact to species on the surface water than on the bottom layer. Species richness increased with horizontal distance from the vent, and continuing for a distance of 2000 m, indicating that the vent fluid may exert a negative impact over several kilometers. The community structure off Kueishan Island displayed numerous transitions along the horizontal gradient, which were broadly congruent with changes in environmental conditions. Combination of variation in Ca2+, Cl-, temperature, pH and depth were revealed to show the strongest correlation with the change in benthic community structure, suggesting multiple factors of vent fluid were influencing the associated fauna. Only the vent crabs of Kueishan Island may have an obligated relationship with vents and inhabit the vent mouths because other fauna found nearby are opportunistic taxa that are more tolerant to acidic and toxic environments. PMID:26849440

CFD analysis of gas explosions vented through relief pipes.

PubMed

Ferrara, G; Di Benedetto, A; Salzano, E; Russo, G

2006-09-21

Vent devices for gas and dust explosions are often ducted to safe locations by means of relief pipes. However, the presence of the duct increases the severity of explosion if compared to simply vented vessels (i.e. compared to cases where no duct is present). Besides, the identification of the key phenomena controlling the violence of explosion has not yet been gained. Multidimensional models coupling, mass, momentum and energy conservation equations can be valuable tools for the analysis of such complex explosion phenomena. In this work, gas explosions vented through ducts have been modelled by a two-dimensional (2D) axi-symmetric computational fluid dynamic (CFD) model based on the unsteady Reynolds Averaged Navier Stokes (RANS) approach in which the laminar, flamelet and distributed combustion models have been implemented. Numerical test have been carried out by varying ignition position, duct diameter and length. Results have evidenced that the severity of ducted explosions is mainly driven by the vigorous secondary explosion occurring in the duct (burn-up) rather than by the duct flow resistance or acoustic enhancement. Moreover, it has been found out that the burn-up affects explosion severity due to the reduction of venting rate rather than to the burning rate enhancement through turbulization.

Reactor pressure vessel head vents and methods of using the same

DOEpatents

Gels, John L; Keck, David J; Deaver, Gerald A

2014-10-28

Internal head vents are usable in nuclear reactors and include piping inside of the reactor pressure vessel with a vent in the reactor upper head. Piping extends downward from the upper head and passes outside of the reactor to permit the gas to escape or be forcibly vented outside of the reactor without external piping on the upper head. The piping may include upper and lowers section that removably mate where the upper head joins to the reactor pressure vessel. The removable mating may include a compressible bellows and corresponding funnel. The piping is fabricated of nuclear-reactor-safe materials, including carbon steel, stainless steel, and/or a Ni--Cr--Fe alloy. Methods install an internal head vent in a nuclear reactor by securing piping to an internal surface of an upper head of the nuclear reactor and/or securing piping to an internal surface of a reactor pressure vessel.

Diversity and phylogenetic analyses of bacteria from a shallow-water hydrothermal vent in Milos island (Greece).

PubMed

Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena; Yakimov, Michail; Vetriani, Costantino

2013-01-01

Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34 × 10(8) cells g(-1). The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94%), revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology.

Diversity and phylogenetic analyses of bacteria from a shallow-water hydrothermal vent in Milos island (Greece)

PubMed Central

Giovannelli, Donato; d'Errico, Giuseppe; Manini, Elena; Yakimov, Michail; Vetriani, Costantino

2013-01-01

Studies of shallow-water hydrothermal vents have been lagging behind their deep-sea counterparts. Hence, the importance of these systems and their contribution to the local and regional diversity and biogeochemistry is unclear. This study analyzes the bacterial community along a transect at the shallow-water hydrothermal vent system of Milos island, Greece. The abundance and biomass of the prokaryotic community is comparable to areas not affected by hydrothermal activity and was, on average, 1.34 × 108 cells g−1. The abundance, biomass and diversity of the prokaryotic community increased with the distance from the center of the vent and appeared to be controlled by the temperature gradient rather than the trophic conditions. The retrieved 16S rRNA gene fragments matched sequences from a variety of geothermal environments, although the average similarity was low (94%), revealing previously undiscovered taxa. Epsilonproteobacteria constituted the majority of the population along the transect, with an average contribution to the total diversity of 60%. The larger cluster of 16S rRNA gene sequences was related to chemolithoautotrophic Sulfurovum spp., an Epsilonproteobacterium so far detected only at deep-sea hydrothermal vents. The presence of previously unknown lineages of Epsilonproteobacteria could be related to the abundance of organic matter in these systems, which may support alternative metabolic strategies to chemolithoautotrophy. The relative contribution of Gammaproteobacteria to the Milos microbial community increased along the transect as the distance from the center of the vent increased. Further attempts to isolate key species from these ecosystems will be critical to shed light on their evolution and ecology. PMID:23847607

A finite element analysis of novel vented dental abutment geometries for cement‐retained crown restorations

PubMed Central

Rodriguez, Lucas C.; Saba, Juliana N.; Meyer, Clark A.; Chung, Kwok‐Hung; Wadhwani, Chandur

2016-01-01

Abstract Recent literature indicates that the long‐term success of dental implants is, in part, attributed to how dental crowns are attached to their associated implants. The commonly utilized method for crown attachment – cementation, has been criticized because of recent links between residual cement and peri‐implant disease. Residual cement extrusion from crown‐abutment margins post‐crown seating is a growing concern. This study aimed at (1) identifying key abutment features, which would improve dental cement flow characteristics, and (2) understanding how these features would impact the mechanical stability of the abutment under functional loads. Computational fluid dynamic modeling was used to evaluate cement flow in novel abutment geometries. These models were then evaluated using 3D‐printed surrogate models. Finite element analysis also provided an understanding of how the mechanical stability of these abutments was altered after key features were incorporated into the geometry. The findings demonstrated that the key features involved in improved venting of the abutment during crown seating were (1) addition of vents, (2) diameter of the vents, (3) location of the vents, (4) addition of a plastic screw insert, and (5) thickness of the abutment wall. This study culminated in a novel design for a vented abutment consisting of 8 vents located radially around the abutment neck‐margin plus a plastic insert to guide the cement during seating and provide retrievability to the abutment system.Venting of the dental abutment has been shown to decrease the risk of undetected residual dental cement post‐cement‐retained crown seating. This article will utilize a finite element analysis approach toward optimizing dental abutment designs for improved dental cement venting. Features investigated include (1) addition of vents, (2) diameter of vents, (3) location of vents, (4) addition of plastic screw insert, and (5) thickness of abutment wall. PMID

A finite element analysis of novel vented dental abutment geometries for cement-retained crown restorations.

PubMed

Rodriguez, Lucas C; Saba, Juliana N; Meyer, Clark A; Chung, Kwok-Hung; Wadhwani, Chandur; Rodrigues, Danieli C

2016-11-01

Recent literature indicates that the long-term success of dental implants is, in part, attributed to how dental crowns are attached to their associated implants. The commonly utilized method for crown attachment - cementation, has been criticized because of recent links between residual cement and peri-implant disease. Residual cement extrusion from crown-abutment margins post-crown seating is a growing concern. This study aimed at (1) identifying key abutment features, which would improve dental cement flow characteristics, and (2) understanding how these features would impact the mechanical stability of the abutment under functional loads. Computational fluid dynamic modeling was used to evaluate cement flow in novel abutment geometries. These models were then evaluated using 3D-printed surrogate models. Finite element analysis also provided an understanding of how the mechanical stability of these abutments was altered after key features were incorporated into the geometry. The findings demonstrated that the key features involved in improved venting of the abutment during crown seating were (1) addition of vents, (2) diameter of the vents, (3) location of the vents, (4) addition of a plastic screw insert, and (5) thickness of the abutment wall. This study culminated in a novel design for a vented abutment consisting of 8 vents located radially around the abutment neck-margin plus a plastic insert to guide the cement during seating and provide retrievability to the abutment system.Venting of the dental abutment has been shown to decrease the risk of undetected residual dental cement post-cement-retained crown seating. This article will utilize a finite element analysis approach toward optimizing dental abutment designs for improved dental cement venting. Features investigated include (1) addition of vents, (2) diameter of vents, (3) location of vents, (4) addition of plastic screw insert, and (5) thickness of abutment wall.

Analysis of the signals recorded by a single OBS/H near the active Longqi hydrothermal vent at the ultraslow spreading Southwest Indian Ridge (49°39´E)

NASA Astrophysics Data System (ADS)

Liu, Y.; Tao, C.; Cai, L.; Qiu, L.

2016-12-01

We developed a long-period seismic monitoring experiment near the active Longqi hydrothermal vent from January to April during the Chinese cruise DY115-34 in 2014. During the 102-day experiment, more than 2,000 seismic signals recorded by a single Ocean bottom Seismometer with Hydrophone (OBS/H) are associated with tectonic activity and magma migration in the hydrothermal field. We classified these signals into four typical classes based on their time-frequency characteristics: 1. more than1800 volcano-tectonic microearthquakes (VTMs) with clear onset of P and S phases, Ts-Tp delay time less than 2 s and small local magnitude; 2. 3 regional earthquakes used to determinate sensor orientation; 3. about a hundred short duration events (SDEs) whose have several narrow peaks in frequency range and high amplitude with an exponential decaying coda in seismograms; 4. several special acoustic signals that have the similar feature in waveform recorded by seismometers and hydrophone, with uncertain of generated by biological or geological activity. Analysis of signals based on its feature: First, located the 1549 VTMs with high signal to noise ratio (SNR) by the single station location (SSL) method based on polarization analysis, the results shows that hypocenters mainly beneath the axial valley ridge (AVR) and extended to upper mantle with depth of 15 km, it indicates magma is still active now beneath the AVR in the Longqi field. Second, activities of earthquakes have a certain rule, during the first 6 days, there is an active period with 21.6 events per day, After a long quiet period of 78 days (3.4 events per day), a larger scale and a longer duration of the earthquakes activity is coming with 79.7 events per day. This reflects the law of intermittent magmatic and hydrothermal activity in the Longqi field. Moreover, complex frequencies characteristics of SDEs ascribed to clusters of some monochromatic waves around different frequencies suggest that SDEs are the combination

Development and field application of a 6-bottle serial gas-tight fluid sampler for collecting seafloor cold seep and hydrothermal vent fluids with autonomous operation capability

NASA Astrophysics Data System (ADS)

Wu, S.; Ding, K.; Yang, C.; Seyfried, W. E., Jr.; Tan, C.; Schaen, A. T.; Luhmann, A. J.

2014-12-01

A 6-bottle serial gas-tight sampler (so-called "six-shooter") was developed for application with deep-sea vent fluids. The new device is composed of a custom-made 6-channel valve manifold and six sampling bottles which are circularly distributed around the valve manifold. Each valve channel consists of a high-pressure titanium cartridge valve and a motor-driven actuator. A sampling snorkel is connected to the inlet of the manifold that delivers the incoming fluid to different bottles. Each sampling bottle has a 160 ml-volume chamber and an accumulator chamber inside where compressed nitrogen is used to maintain the sample at near in-situ pressure. An electronics chamber that is located at the center of the sampler is used to carry out all sampling operations, autonomously, if desired. The sampler is of a compact circular configuration with a diameter of 26 cm and a length of 54 cm. During the SVC cruise AT 26-12, the sampler was deployed by DSV2 Alvin at a cold seep site MC036 with a depth of 1090 m in the Gulf of Mexico. The sampler collected fluid samples automatically following the tidal cycle to monitor the potential impact of the tide cycle on the fluid chemistry of cold seep in a period of two day. During the cruise AT 26-17, the sampler was used with newly upgraded DSV2 Alvin three times at the hydrothermal vent sites along Axial Seamount and Main Endeavor Field on Juan de Fuca Ridge. During a 4-day deployment at Anemone diffuse site (Axial Caldera), the sampler was set to work in an autonomous mode to collect fluid samples according to the preset interval. During other dives, the sampler was manually controlled via ICL (Inductively Coupled Link) communication through the hull. Gas-tight fluid samples were collected from different hydrothermal vents with temperatures between 267 ℃ and 335 ℃ at the depth up to 2200 m. The field results indicate unique advantages of the design. It can be deployed in extended time period with remote operation or working

Rapid growth of mineral deposits at artificial seafloor hydrothermal vents

PubMed Central

Nozaki, Tatsuo; Ishibashi, Jun-Ichiro; Shimada, Kazuhiko; Nagase, Toshiro; Takaya, Yutaro; Kato, Yasuhiro; Kawagucci, Shinsuke; Watsuji, Tomoo; Shibuya, Takazo; Yamada, Ryoichi; Saruhashi, Tomokazu; Kyo, Masanori; Takai, Ken

2016-01-01

Seafloor massive sulphide deposits are potential resources for base and precious metals (Cu-Pb-Zn ± Ag ± Au), but difficulties in estimating precise reserves and assessing environmental impacts hinder exploration and commercial mining. Here, we report petrological and geochemical properties of sulphide chimneys less than 2 years old that formed where scientific boreholes vented hydrothermal fluids in the Iheya-North field, Okinawa Trough, in East China Sea. One of these infant chimneys, dominated by Cu-Pb-Zn-rich sulphide minerals, grew a height of 15 m within 25 months. Portions of infant chimneys are dominated by sulphate minerals. Some infant chimneys are sulphide-rich similar to high-grade Cu-Pb-Zn bodies on land, albeit with relatively low As and Sb concentrations. The high growth rate reaching the 15 m height within 25 months is attributed to the large hydrothermal vent more than 50 cm in diameter created by the borehole, which induced slow mixing with the ambient seawater and enhanced efficiency of sulphide deposition. These observations suggest the possibility of cultivating seafloor sulphide deposits and even controlling their growth and grades through manipulations of how to mix and quench hydrothermal fluids with the ambient seawater. PMID:26911272

The Tiptop coal-mine fire, Kentucky: Preliminary investigation of the measurement of mercury and other hazardous gases from coal-fire gas vents

USGS Publications Warehouse

Hower, J.C.; Henke, K.; O'Keefe, J.M.K.; Engle, M.A.; Blake, D.R.; Stracher, G.B.

2009-01-01

The Tiptop underground coal-mine fire in the Skyline coalbed of the Middle Pennsylvanian Breathitt Formation was investigated in rural northern Breathitt County, Kentucky, in May 2008 and January 2009, for the purpose of determining the concentrations of carbon dioxide (CO2), carbon monoxide (CO), and mercury (Hg) in the vent and for measuring gas-vent temperatures. At the time of our visits, concentrations of CO2 peaked at 2.0% and > 6.0% (v/v) and CO at 600 ppm and > 700 ppm during field analysis in May 2008 and January 2009, respectively. For comparison, these concentrations exceed the U.S. Occupational Safety & Health Administration (OSHA) eight-hour safe exposure limits (0.5% CO2 and 50 ppm CO), although the site is not currently mined. Mercury, as Hg0, in excess of 500 and 2100 ??g/m3, in May and January, respectively, in the field, also exceeded the OSHA eight-hour exposure limit (50 ??g/m3). Carbonyl sulfide, dimethyl sulfide, carbon disulfide, and a suite of organic compounds were determined at two vents for the first sampling event. All gases are diluted by air as they exit and migrate away from a gas vent, but temperature inversions and other meteorological conditions could lead to unhealthy concentrations in the nearby towns. Variation in gas temperatures, nearly 300 ??C during the January visit to the fire versus < 50 ??C in May, demonstrates the large temporal variability in fire intensity at the Tiptop mine. These preliminary results suggest that emissions from coal fires may be important, but additional data are required that address the reasons for significant variations in the composition, flow, and temperature of vent gases. ?? 2009 Elsevier B.V.

First insights into macro- and meiofaunal colonisation patterns on paired wood/slate substrata at Atlantic deep-sea hydrothermal vents

NASA Astrophysics Data System (ADS)

Cuvelier, Daphne; Beesau, Julie; Ivanenko, Viatcheslav N.; Zeppilli, Daniela; Sarradin, Pierre-Marie; Sarrazin, Jozée

2014-05-01

In 2006, paired wood and slate panels, each equipped with a temperature probe, were deployed on three different localities on and around the Eiffel Tower edifice (Lucky Strike vent field, Mid-Atlantic Ridge) within close proximity of visible hydrothermal activity. Recovery of these panels took place in 2008. For this two-year deployment period, the composition of colonising organisms (both macro-and meiofauna) was assessed, along with image analyses of the deployment sites in 2006 and 2008. Very few significant differences in colonisation between organic (wood) and inorganic (slate) panels were revealed. Rather, the locality of deployment and the local environmental conditions and hydrothermal activity were found to influence taxonomic composition. Variability in microhabitat conditions and biological interactions were hypothesised to interact jointly in shaping new faunal communities on the colonisation substrata.

Larvae from afar colonize deep-sea hydrothermal vents after a catastrophic eruption

PubMed Central

Mullineaux, Lauren S.; Adams, Diane K.; Mills, Susan W.; Beaulieu, Stace E.

2010-01-01

The planktonic larval stage is a critical component of life history in marine benthic species because it confers the ability to disperse, potentially connecting remote populations and leading to colonization of new sites. Larval-mediated connectivity is particularly intriguing in deep-sea hydrothermal vent communities, where the habitat is patchy, transient, and often separated by tens or hundreds of kilometers. A recent catastrophic eruption at vents near 9°50′N on the East Pacific Rise created a natural clearance experiment and provided an opportunity to study larval supply in the absence of local source populations. Previous field observations have suggested that established vent populations may retain larvae and be largely self-sustaining. If this hypothesis is correct, the removal of local populations should result in a dramatic change in the flux, and possibly species composition, of settling larvae. Fortuitously, monitoring of larval supply and colonization at the site had been established before the eruption and resumed shortly afterward. We detected a striking change in species composition of larvae and colonists after the eruption, most notably the appearance of the gastropod Ctenopelta porifera, an immigrant from possibly more than 300 km away, and the disappearance of a suite of species that formerly had been prominent. This switch demonstrates that larval supply can change markedly after removal of local source populations, enabling recolonization via immigrants from distant sites with different species composition. Population connectivity at this site appears to be temporally variable, depending not only on stochasticity in larval supply, but also on the presence of resident populations. PMID:20385811

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

33 CFR 159.61 - Vents.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE... to minimize clogging by either the contents of the tank or climatic conditions such as snow or ice. ...

33 CFR 159.61 - Vents.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE... to minimize clogging by either the contents of the tank or climatic conditions such as snow or ice. ...

33 CFR 159.61 - Vents.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE... to minimize clogging by either the contents of the tank or climatic conditions such as snow or ice. ...

33 CFR 159.61 - Vents.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Vents. 159.61 Section 159.61 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION MARINE... to minimize clogging by either the contents of the tank or climatic conditions such as snow or ice. ...

Event Detection for Hydrothermal Plumes: A case study at Grotto Vent

NASA Astrophysics Data System (ADS)

Bemis, K. G.; Ozer, S.; Xu, G.; Rona, P. A.; Silver, D.

2012-12-01

Evidence is mounting that geologic events such as volcanic eruptions (and intrusions) and earthquakes (near and far) influence the flow rates and temperatures of hydrothermal systems. Connecting such suppositions to observations of hydrothermal output is challenging, but new ongoing time series have the potential to capture such events. This study explores using activity detection, a technique modified from computer vision, to identify pre-defined events within an extended time series recorded by COVIS (Cabled Observatory Vent Imaging Sonar) and applies it to a time series, with gaps, from Sept 2010 to the present; available measurements include plume orientation, plume rise rate, and diffuse flow area at the NEPTUNE Canada Observatory at Grotto Vent, Main Endeavour Field, Juan de Fuca Ridge. Activity detection is the process of finding a pattern (activity) in a data set containing many different types of patterns. Among many approaches proposed to model and detect activities, we have chosen a graph-based technique, Petri Nets, as they do not require training data to model the activity. They use the domain expert's knowledge to build the activity as a combination of feature states and their transitions (actions). Starting from a conceptual model of how hydrothermal plumes respond to daily tides, we have developed a Petri Net based detection algorithm that identifies deviations from the specified response. Initially we assumed that the orientation of the plume would change smoothly and symmetrically in a consistent daily pattern. However, results indicate that the rate of directional changes varies. The present Petri Net detects unusually large and rapid changes in direction or amount of bending; however inspection of Figure 1 suggests that many of the events detected may be artifacts resulting from gaps in the data or from the large temporal spacing. Still, considerable complexity overlies the "normal" tidal response pattern (the data has a dominant frequency of

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.

S-33 constraints on the seawater sulfate contribution in modern seafloor hydrothermal vent sulfides

USGS Publications Warehouse

Ono, Shuhei; Shanks, Wayne C.; Rouxel, O.J.; Rumble, D.

2007-01-01

Sulfide sulfur in mid-oceanic ridge hydrothermal vents is derived from leaching of basaltic-sulfide and seawater-derived sulfate that is reduced during high temperature water rock interaction. Conventional sulfur isotope studies, however, are inconclusive about the mass-balance between the two sources because 34S/32S ratios of vent fluid H2S and chimney sulfide minerals may reflect not only the mixing ratio but also isotope exchange between sulfate and sulfide. Here, we show that high-precision analysis of S-33 can provide a unique constraint because isotope mixing and isotope exchange result in different ??33S (?????33S-0.515 ??34S) values of up to 0.04??? even if ??34S values are identical. Detection of such small ??33S differences is technically feasible by using the SF6 dual-inlet mass-spectrometry protocol that has been improved to achieve a precision as good as 0.006??? (2??). Sulfide minerals (marcasite, pyrite, chalcopyrite, and sphalerite) and vent H2S collected from four active seafloor hydrothermal vent sites, East Pacific Rise (EPR) 9-10??N, 13??N, and 21??S and Mid-Atlantic Ridge (MAR) 37??N yield ??33S values ranging from -0.002 to 0.033 and ??34S from -0.5??? to 5.3???. The combined ??34S and ??33S systematics reveal that 73 to 89% of vent sulfides are derived from leaching from basaltic sulfide and only 11 to 27% from seawater-derived sulfate. Pyrite from EPR 13??N and marcasite from MAR 37??N are in isotope disequilibrium not only in ??34S but also in ??33S with respect to associated sphalerite and chalcopyrite, suggesting non-equilibrium sulfur isotope exchange between seawater sulfate and sulfide during pyrite precipitation. Seafloor hydrothermal vent sulfides are characterized by low ??33S values compared with biogenic sulfides, suggesting little or no contribution of sulfide from microbial sulfate reduction into hydrothermal sulfides at sediment-free mid-oceanic ridge systems. We conclude that 33S is an effective new tracer for interplay among

When did decapods invade hydrothermal vents? Clues from the Western Pacific and Indian Oceans.

PubMed

Yang, Jin-Shu; Lu, Bo; Chen, Dian-Fu; Yu, Yan-Qin; Yang, Fan; Nagasawa, Hiromichi; Tsuchida, Shinji; Fujiwara, Yoshihiro; Yang, Wei-Jun

2013-02-01

Hydrothermal vents are typically located in midocean ridges and back-arc basins and are usually generated by the movement of tectonic plates. Life thrives in these environments despite the extreme conditions. In addition to chemoautotrophic bacteria, decapod crustaceans are dominant in many of the hydrothermal vents discovered to date. Contrary to the hypothesis that these species are remnants of relic fauna, increasing evidence supports the notion that hydrothermal vent decapods have diversified in more recent times with previous research attributing the origin of alvinocarid shrimps to the Miocene. This study investigated seven representative decapod species from four hydrothermal vents throughout the Western Pacific and Indian Oceans. A partitioned mix-model phylogenomic analysis of mitochondrial DNA produced a consistent phylogenetic topology of these vent-endemic species. Additionally, molecular dating analysis calibrated using multiple fossils suggested that both bythograeid crabs and alvinocarid shrimps originated in the late Mesozoic and early Cenozoic. Although of limited sampling, our estimates support the extinction/repopulation hypothesis, which postulates recent diversification times for most hydrothermal vent species due to their mass extinction by global deep-water anoxic/dysoxic events during the Late Cretaceous and Early Tertiary. The continental-derived property of the West Pacific province is compatible with the possibility that vent decapods diversified from ancestors from shallow-water regions such as cold seeps. Our results move us a step closer toward understanding the evolutionary origin of hydrothermal vent species and their distribution in the Western Pacific-Indian Ocean Region.

Exploring the influence of vent location and eruption style on tephra fall hazard from the Okataina Volcanic Centre, New Zealand

NASA Astrophysics Data System (ADS)

Thompson, Mary Anne; Lindsay, Jan M.; Sandri, Laura; Biass, Sébastien; Bonadonna, Costanza; Jolly, Gill; Marzocchi, Warner

2015-05-01

Uncertainties in modelling volcanic hazards are often amplified in geographically large systems which have a diverse eruption history that comprises variable eruption styles from many different vent locations. The ~700 km2 Okataina Volcanic Centre (OVC) is a caldera complex in New Zealand which has displayed a range of eruption styles and compositions over its current phase of activity (26 ka-present), including one basaltic maar-forming eruption, one basaltic Plinian eruption and nine rhyolitic Plinian eruptions. All three of these eruption styles occurred within the past 3.5 ky, and any of these styles could occur in the event of a future eruption. The location of a future eruption is also unknown. Future vents could potentially open in one of three different areas which have been activated in the past 26 ky at the OVC: the Tarawera linear vent zone (LVZ) (five eruptions), the Haroharo LVZ (five eruptions) or outside of these LVZs (one eruption). A future rhyolitic or basaltic Plinian eruption from the OVC is likely to generate widespread tephra fall in loads that will cause significant disruption and have severe socio-economic impacts. Past OVC tephra hazard studies have focused on evaluating hazard from a rhyolitic Plinian eruption at select vent locations in the OVC's Tarawera LVZ. Here, we expand upon past studies by evaluating tephra hazard for all possible OVC eruption vent areas and for both rhyolitic and basaltic Plinian eruption styles, and explore how these parameters influence tephra hazard forecasts. Probabilistic volcanic hazard model BET_VH and advection-diffusion model TEPHRA2 were used to assess the hazard of accumulating ≥10 kg m-2 of tephra from both basaltic Plinian and rhyolitic Plinian eruption styles, occurring from within the Tarawera LVZ, the Haroharo LVZ or other potential vent areas within the caldera. Our results highlight the importance of considering all the potential vent locations of a volcanic system, in order to capture the full

Modelling hydrothermal venting in volcanic sedimentary basins: Impact on hydrocarbon maturation and paleoclimate

NASA Astrophysics Data System (ADS)

Iyer, Karthik; Schmid, Daniel W.; Planke, Sverre; Millett, John

2017-06-01

Vent structures are intimately associated with sill intrusions in sedimentary basins globally and are thought to have been formed contemporaneously due to overpressure generated by gas generation during thermogenic breakdown of kerogen or boiling of water. Methane and other gases generated during this process may have driven catastrophic climate change in the geological past. In this study, we present a 2D FEM/FVM model that accounts for 'explosive' vent formation by fracturing of the host rock based on a case study in the Harstad Basin, offshore Norway. Overpressure generated by gas release during kerogen breakdown in the sill thermal aureole causes fracture formation. Fluid focusing and overpressure migration towards the sill tips results in vent formation after only few tens of years. The size of the vent depends on the region of overpressure accessed by the sill tip. Overpressure migration occurs in self-propagating waves before dissipating at the surface. The amount of methane generated in the system depends on TOC content and also on the type of kerogen present in the host rock. Generated methane moves with the fluids and vents at the surface through a single, large vent structure at the main sill tip matching first-order observations. Violent degassing takes place within the first couple of hundred years and occurs in bursts corresponding to the timing of overpressure waves. The amount of methane vented through a single vent is only a fraction (between 5 and 16%) of the methane generated at depth. Upscaling to the Vøring and Møre Basins, which are a part of the North Atlantic Igneous Province, and using realistic host rock carbon content and kerogen values results in a smaller amount of methane vented than previously estimated for the PETM. Our study, therefore, suggests that the negative carbon isotope excursion (CIE) observed in the fossil record could not have been caused by intrusions within the Vøring and Møre Basins alone and that a contribution

Genetic diversity and demographic instability in Riftia pachyptila tubeworms from eastern Pacific hydrothermal vents

PubMed Central

2011-01-01

Background Deep-sea hydrothermal vent animals occupy patchy and ephemeral habitats supported by chemosynthetic primary production. Volcanic and tectonic activities controlling the turnover of these habitats contribute to demographic instability that erodes genetic variation within and among colonies of these animals. We examined DNA sequences from one mitochondrial and three nuclear gene loci to assess genetic diversity in the siboglinid tubeworm, Riftia pachyptila, a widely distributed constituent of vents along the East Pacific Rise and Galápagos Rift. Results Genetic differentiation (FST) among populations increased with geographical distances, as expected under a linear stepping-stone model of dispersal. Low levels of DNA sequence diversity occurred at all four loci, allowing us to exclude the hypothesis that an idiosyncratic selective sweep eliminated mitochondrial diversity alone. Total gene diversity declined with tectonic spreading rates. The southernmost populations, which are subjected to superfast spreading rates and high probabilities of extinction, are relatively homogenous genetically. Conclusions Compared to other vent species, DNA sequence diversity is extremely low in R. pachyptila. Though its dispersal abilities appear to be effective, the low diversity, particularly in southern hemisphere populations, is consistent with frequent local extinction and (re)colonization events. PMID:21489281

40 CFR 265.1088 - Standards: Closed-vent systems and control devices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 25 2010-07-01 2010-07-01 false Standards: Closed-vent systems and control devices. 265.1088 Section 265.1088 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Containers § 265.1088 Standards: Closed-vent systems and control devices. (a) This section applies to each...

The pH and pCO2 dependence of sulfate reduction in shallow-sea hydrothermal CO2 - venting sediments (Milos Island, Greece).