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Sample records for extended marine oxygen

  1. Extending the Marine Microcosm Laboratory

    ERIC Educational Resources Information Center

    Ryswyk, Hal Van; Hall, Eric W.; Petesch, Steven J.; Wiedeman, Alice E.

    2007-01-01

    The traditional range of marine microcosm laboratory experiments is presented as an ideal environment to teach the entire analysis process. The microcosm lab provides student-centered approach with opportunities for collaborative learning and to develop critical communication skills.

  2. Identification of an Archean marine oxygen oasis

    SciTech Connect

    Riding, Dr Robert E; Fralick, Dr Philip; Liang, Liyuan

    2014-01-01

    The early Earth was essentially anoxic. A number of indicators suggest the presence of oxygenic photosynthesis 2700 3000 million years (Ma) ago, but direct evidence for molecular oxygen (O2) in seawater has remained elusive. Here we report rare earth element (REE) analyses of 2800 million year old shallowmarine limestones and deep-water iron-rich sediments at Steep Rock Lake, Canada. These show that the seawater from which extensive shallow-water limestones precipitated was oxygenated, whereas the adjacent deeper waters where iron-rich sediments formed were not. We propose that oxygen promoted limestone precipitation by oxidative removal of dissolved ferrous iron species, Fe(II), to insoluble Fe(III) oxyhydroxide, and estimate that at least 10.25 M oxygen concentration in seawater was required to accomplish this at Steep Rock. This agrees with the hypothesis that an ample supply of dissolved Fe(II) in Archean oceans would have hindered limestone formation. There is no direct evidence for the oxygen source at Steep Rock, but organic carbon isotope values and diverse stromatolites in the limestones suggest the presence of cyanobacteria. Our findings support the view that during the Archean significant oxygen levels first developed in protected nutrient-rich shallow marine habitats. They indicate that these environments were spatially restricted, transient, and promoted limestone precipitation. If Archean marine limestones in general reflect localized oxygenic removal of dissolved iron at the margins of otherwise anoxic iron-rich seas, then early oxygen oases are less elusive than has been assumed.

  3. Marine biogeochemistry: The ups and downs of ocean oxygen

    NASA Astrophysics Data System (ADS)

    Doney, Scott C.; Steinberg, Deborah K.

    2013-07-01

    The daily vertical migration of small marine animals transfers organic carbon from the surface ocean to depth. An assessment of acoustic data reveals that the depth of migration is closely tied to subsurface oxygen levels throughout much of the global ocean.

  4. Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Casciotti, Karen L.

    2016-01-01

    The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

  5. Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle.

    PubMed

    Casciotti, Karen L

    2016-01-01

    The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status. PMID:26747521

  6. Mars atmosphere during the Mariner 9 extended mission: Television results

    NASA Technical Reports Server (NTRS)

    Leovy, C. B.; Briggs, G. A.; Smith, B. A.

    1973-01-01

    Data from the Mariner 9 extended mission provide a record of seasonally varying processes from mid-spring to early summer in the Northern Hemisphere of Mars. Atmospheric phenomena observed by the television cameras during this period are: (1) A faint shelf of brightness near 20 km in height; (2) condensate clouds over Hellas in the early morning, (3) wave clouds over the south polar region indicating strong west to east winds; (4) faint wave clouds over the north polar cap indicating northeast to southwest flow off the cap; and (5) clouds over the major vocanos and Tithonius Lacus which show remarkable repeatability, strong topographic control, and, in some cases, evidence for convective structure.

  7. Reactive Oxygen Species and Autophagy Modulation in Non-Marine Drugs and Marine Drugs

    PubMed Central

    Farooqi, Ammad Ahmad; Fayyaz, Sundas; Hou, Ming-Feng; Li, Kun-Tzu; Tang, Jen-Yang; Chang, Hsueh-Wei

    2014-01-01

    It is becoming more understandable that an existing challenge for translational research is the development of pharmaceuticals that appropriately target reactive oxygen species (ROS)-mediated molecular networks in cancer cells. In line with this approach, there is an overwhelmingly increasing list of many non-marine drugs and marine drugs reported to be involved in inhibiting and suppressing cancer progression through ROS-mediated cell death. In this review, we describe the strategy of oxidative stress-based therapy and connect the ROS modulating effect to the regulation of apoptosis and autophagy. Finally, we focus on exploring the function and mechanism of cancer therapy by the autophagy modulators including inhibitors and inducers from non-marine drugs and marine drugs. PMID:25402829

  8. Oxygen diffusion in marine-derived tissue engineering scaffolds.

    PubMed

    Boccardi, E; Belova, I V; Murch, G E; Boccaccini, A R; Fiedler, T

    2015-06-01

    This paper addresses the computation of the effective diffusivity in new bioactive glass (BG) based tissue engineering scaffolds. High diffusivities facilitate the supply of oxygen and nutrients to grown tissue as well as the rapid disposal of toxic waste products. The present study addresses required novel types of bone tissue engineering BG scaffolds that are derived from natural marine sponges. Using the foam replication method, the scaffold geometry is defined by the porous structure of Spongia Agaricina and Spongia Lamella. These sponges present the advantage of attaining scaffolds with higher mechanical properties (2-4 MPa) due to a decrease in porosity (68-76%). The effective diffusivities of these structures are compared with that of conventional scaffolds based on polyurethane (PU) foam templates, characterised by high porosity (>90%) and lower mechanical properties (>0.05 MPa). Both the spatial and directional variations of diffusivity are investigated. Furthermore, the effect of scaffold decomposition due to immersion in simulated body fluid (SBF) on the diffusivity is addressed. Scaffolds based on natural marine sponges are characterised by lower oxygen diffusivity due to their lower porosity compared with the PU replica foams, which should enable the best oxygen supply to newly formed bone according the numerical results. The oxygen diffusivity of these new BG scaffolds increases over time as a consequence of the degradation in SBF. PMID:26111951

  9. Marine oxygen holes as a consequence of oceanic acidification

    NASA Astrophysics Data System (ADS)

    Hofmann, M.; Schellnhuber, H.-J.

    2009-04-01

    An increase of atmospheric CO2 levels will not only drive future global mean temperatures towards values unprecedented during the whole Quaternary, but will also lead to an acidification of sea water which could harm the marine biota. Here we assess possible impacts of elevated atmospheric CO2 concentrations on the marine biological carbon pump by utilizing a business-as-usual emission scenario of anthropogenic CO2. A corresponding release of 4075 Petagrams of Carbon in total has been applied to simulate the current millennium by employing an Earth System Model of Intermediate Complexity (EMIC). This work is focused on studying the implications of reduced biogenic calcification caused by an increasing degree of oceanic acidification on the marine biological carbon pump. The attenuation of biogenic calcification imposes a small negative feedback on rising atmospheric pCO2 levels, tending to stabilize the Earth's climate. Since mineral ballast, notably particulate CaCO3, plays a dominant role in carrying organic matter through the water column, a reduction of its export fluxes weakens the strength of the biological carbon pump. There is, however, a dramatic effect discovered in our model world with severe consequences: since organic matter is oxidized in shallow waters when mineral-ballast fluxes weaken, oxygen holes (hypoxic zones) start to expand considerably in the oceans with potentially harmful impacts on a variety of marine ecosystems. Our study indicates that unbridled ocean acidification would exacerbate the observed hypoxia trends due to various environmental factors as reported in recent empirical studies.

  10. Marine Nitrogen loss in Oxygen minimum zones: a modeling approach

    NASA Astrophysics Data System (ADS)

    Six, Katharina; Hense, Inga; Ilyina, Tatiana

    2015-04-01

    In the oxygen minimum zones (OMZ) of the global ocean fixed nitrogen is lost by two pathways: heterotrophic denitrification and anaerobic ammonium oxidation (anammox). Lab experiments show that denitrification and anammox occur at a ratio of about 70:30 depending on the amount and the C:N ratio of the available organic matter. However, observations in the OMZ are sparse and, thus, the contribution of anammox to the global loss of fixed nitrogen is still under debate. In addition, it is projected that the OMZ expand in the future due to global warming. This compels an urgent need to understand the controlling mechanisms of nitrogen loss in OMZ. Global biogeochemical ocean models assessed in the last IPCC have a rather poor representation of nitrogen related processes, primarily focusing on nitrate. These models do not include the nitrogen loss by anammox as they lack a representation of ammonium and nitrite. Here we present results of a more comprehensive marine nitrogen cycle including interactions between nitrate, nitrite, ammonium and organic matter in the water column and the sediments in the framework of HAMOCC, the global biogeochemical ocean model of the Max Planck Institute for Meteorology. The representation of a stepwise dissimilatory nitrate reduction to nitrite and ammonium captures observed features like the secondary nitrite maximum. We set up a global marine nitrogen budget and discuss changes in the subsurface oxygen distributions.

  11. Enzymatic Production of Extracellular Reactive Oxygen Species by Marine Microorganisms

    NASA Astrophysics Data System (ADS)

    Diaz, J. M.; Andeer, P. F.; Hansel, C. M.

    2014-12-01

    Reactive oxygen species (ROS) serve as intermediates in a myriad of biogeochemically important processes, including cell signaling pathways, cellular oxidative stress responses, and the transformation of both nutrient and toxic metals such as iron and mercury. Abiotic reactions involving the photo-oxidation of organic matter were once considered the only important sources of ROS in the environment. However, the recent discovery of substantial biological ROS production in marine systems has fundamentally shifted this paradigm. Within the last few decades, marine phytoplankton, including diatoms of the genus Thalassiosira, were discovered to produce ample extracellular quantities of the ROS superoxide. Even more recently, we discovered widespread production of extracellular superoxide by phylogenetically and ecologically diverse heterotrophic bacteria at environmentally significant levels (up to 20 amol cell-1 hr-1), which has introduced the revolutionary potential for substantial "dark" cycling of ROS. Despite the profound biogeochemical importance of extracellular biogenic ROS, the cellular mechanisms underlying the production of this ROS have remained elusive. Through the development of a gel-based assay to identify extracellular ROS-producing proteins, we have recently found that enzymes typically involved in antioxidant activity also produce superoxide when molecular oxygen is the only available electron acceptor. For example, large (~3600 amino acids) heme peroxidases are involved in extracellular superoxide production by a bacterium within the widespread Roseobacter clade. In Thalassiosira spp., extracellular superoxide is produced by flavoproteins such as glutathione reductase and ferredoxin NADP+ reductase. Thus, extracellular ROS production may occur via secreted and/or cell surface enzymes that modulate between producing and degrading ROS depending on prevailing geochemical and/or ecological conditions.

  12. NC10 Bacteria in a Marine Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Padilla, C. C.; Bristow, L. A.; Benson, C. R.; Sarode, N. D.; Girguis, P. R.; Glass, J. B.; DiChristina, T. J.; Thamdrup, B.; Stewart, F. J.

    2014-12-01

    Marine oxygen minimum zones (OMZs) are key regions of nitrogen cycling and nitrogen loss as N2. The potential for methane cycling to influence OMZ nitrogen budgets remains largely unknown. The anaerobic oxidation of methane (AOM) coupled to nitrite or nitrate reduction has been shown to be a potential source of methane consumption, N loss, and oxygen production in freshwater sediments, but has not been described for marine pelagic environments. Nitrite-dependent AOM is performed by bacteria of the candidate division NC10 through an intra-aerobic pathway involving the dismutation of nitric oxide to O2 and N2. We explored the potential that NC10-like bacteria are present and active in the anoxic, nitrite-rich OMZ of the Eastern Tropical North Pacific. Community transcriptome sequencing confirmed the expression of genes with top matches to the NC10 bacterium 'Candidatus Methylomirabilis oxyfera.' NC10-like transcripts increased in relative abundance with depth into the anoxic OMZ core and included genes of aerobic methanotrophy and denitrification, as well as high numbers of transcripts matching norZ nitric oxide reductase, hypothesized to play a role in the O2-yielding dismutation reaction. Phylogenetic analysis of OMZ particulate methane monooxygenase (pmoA) and 16S rRNA gene sequences recovered by PCR revealed multiple clades of NC10 phylotypes in the OMZ. Preliminary data from OMZ enrichments revealed methane-dependent nitrite consumption, but further characterization is required to identify the pathways and organisms mediating this process. These findings expand the known environmental range of NC10 and suggest the possibility of previously uncharacterized linkages between OMZ nitrogen and methane cycles.

  13. Using oxygen species to measure marine production in Drake Passage

    NASA Astrophysics Data System (ADS)

    Castro Morales, Karel; Cassar, Nicolas; Bender, Michael; Kaiser, Jan

    2010-05-01

    Marine biological production is key to understanding the global carbon cycle, particularly the role of the Southern Ocean as a sink of CO2. Measurements of oxygen in the surface ocean allow quantifying marine biological productivity, since CO2 and O2 are linked via photosynthesis and respiration. Measurements of O2/Ar ratios and dissolved O2 isotopologues, together with wind-speed gas exchange parameterizations, give estimates of biological oxygen air-sea fluxes (Fbio) and gross photosynthetic production (G) in the mixed layer (zmix). In the absence of vertical mixing, Fbio can be used as a proxy for net community production (N). O2/Ar ratios and O2 concentrations were measured continuously in the uncontaminated seawater supply on board the RRS James Clark Ross along two sections across Drake Passage (DP). The DP1 section (southbound, 27 February-3 March 2007) represented mid-summer; DP2 represented early autumn (northbound, 12-15 April, 2007). The time difference between the two transects was 40 days. Weighted average gas exchange rates were calculated using the WOCE-NODC ocean mixed layer depth climatology and ECMWF wind speeds over 60 days prior to sample collection. The WOCE-NODC climatology shows a deepening of the zmix by on average 46 m within 40 days. The sea surface temperature decreased about 2.4 °C from DP1 to DP2. This reflects the seasonal transition from late summer to early autumn. In agreement with previous observations, we observed a strong north-south gradient of biological oxygen production in the DP. Our results also show high temporal variability over the course of 40 days. During late summer, the physical supersaturation contributes to about 3.6% of the total O2 supersaturation (?O2) for the Subantarctic and Polar Frontal Zones (SAZ and PFZ, respectively). In the other hand, the biological O2 supersaturation (?O2/Ar) showed mainly positive and homogeneous values (~1%) along the Antarctic Zone and Southern Antarctic Circumpolar Current Zone

  14. Microbial cycling, oxidative weathering, and the triple oxygen isotope consequences for marine sulfate

    NASA Astrophysics Data System (ADS)

    Johnston, D. T.; Cowie, B.; Turchyn, A. V.; Antler, G.; Gill, B. C.; Berelson, W.

    2015-12-01

    Microorganisms are responsible for most geochemical sulfur cycling in the ocean. On both modern and geological time scales, stable isotope ratios often serve as a mechanism to track conspicuous or coupled microbial processes, which in turn inform burial fluxes. The most common example of this approach is the use of sulfur isotopes in sulfate and sulfide (both aqueous and in mineral form) to track everything from rates of microbial processes through to the presence/absence of certain metabolic processes in a given environment. The use of oxygen isotope ratios in sulfate has developed in a similar fashion, providing complementary information to that of sulfur isotopes. Through our current work, we will extend the application of oxygen isotopes to include the trace stable oxygen isotope, 17O. These data are facilitated by a new laser F2 fluorination technique running at Harvard, and accompanied by the calibration of a suite of common sulfate standards. At first blush, 16O - 17O - 18O systematics should carry mass-dependent microbial fractionations with process-specific mass laws that are resolvable at the level of our analytical precision. We look to calibrate these biogeochemical effects through the integrated picture captured in marine pore water sulfate profiles, where the 18O/16O is known to evolve. In compliment, riverine sulfate (the sulfate input to the ocean) is an oxidative weathering product and is posited to carry a memory effect of tropospheric O2. Interestingly, the 17O/16O of that O2 carries a mass-independent signal reflecting the balance between stratospheric reactions and Earth surface biospheric fluxes. Through this presentation, we look to calibrate the controls on the balance between biospheric and atmospheric contributions to the marine sulfate reservoir. This is enabled by a series of isotope mass-balance models and with the ultimate goal of developing the geological triple oxygen isotope records of sulfate as a new environmental proxy for paleo

  15. Biofilm history and oxygen availability interact to affect habitat selection in a marine invertebrate.

    PubMed

    Lagos, Marcelo E; White, Craig R; Marshall, Dustin J

    2016-07-01

    In marine systems, oxygen availability varies at small temporal and spatial scales, such that current oxygen levels may not reflect conditions of the past. Different studies have shown that marine invertebrate larvae can select settlement sites based on local oxygen levels and oxygenation history of the biofilm, but no study has examined the interaction of both. The influence of normoxic and hypoxic water and oxygenation history of biofilms on pre-settlement behavior and settlement of the bryozoan Bugula neritina was tested. Larvae used cues in a hierarchical way: the oxygen levels in the water prime larvae to respond, the response to different biofilms is contingent on oxygen levels in the water. When oxygen levels varied throughout biofilm formation, larvae responded differently depending on the history of the biofilm. It appears that B. neritina larvae integrate cues about current and historical oxygen levels to select the appropriate microhabitat and maximize their fitness. PMID:27169475

  16. Extending Hydrologic Information Systems to accommodate Arctic marine observations data

    NASA Astrophysics Data System (ADS)

    Hersh, Eric S.; Maidment, David R.

    2014-04-01

    The Chukchi Sea Offshore Monitoring in Drilling Area - Chemical and Benthos (COMIDA CAB) project characterizes the biota and chemistry of the continental shelf ecosystem of a region of the Chukchi Sea to form a baseline survey of environmental conditions before drilling for oil commences. This paper describes the COMIDA CAB project data and processing methods, which provide a novel approach to data tracking and archiving from marine sampling cruises. This approach features an adaptation of the Consortium of Universities for the Advancement of Hydrologic Science. Observations Data Model for application with physical, chemical, and biological oceanographic data - a new extension of the CUAHSI Hydrologic Information System - thus bringing hydroinformatics into the oceanographic realm. Environmental sampling has been carried out by five separate scientific teams who characterize particular classes of physical, chemical and biological variables, and who each have their own methods of processing samples in their laboratories following the two sampling cruises made to the Chukchi Sea in the summers of 2009 and 2010. The results of their observations and analyses are stored in data files, mostly in Excel format, whose structure is defined differently by each scientific team. In all, the 2009 and 2010 COMIDA CAB field efforts yielded a database of 510,405 data values. Of these, 474,129 were derived from continuous in-situ data sonde profiles and 36,276 were derived from non-sonde extracted samples of the sediment, epibenthos, and water column. These data values represent 301 variables measured at 65 sites and originated from 26 different source files. The biological observations represented 519 distinct taxa. The data from these files are transformed and synthesized into a comprehensive project database in which a set of standardized descriptors of each observed data value are specified and each data value is linked to the data file from which it was created to establish a

  17. Extending Marine Species Distribution Maps Using Non-Traditional Sources

    PubMed Central

    Moretzsohn, Fabio; Gibeaut, James

    2015-01-01

    Abstract Background Traditional sources of species occurrence data such as peer-reviewed journal articles and museum-curated collections are included in species databases after rigorous review by species experts and evaluators. The distribution maps created in this process are an important component of species survival evaluations, and are used to adapt, extend and sometimes contract polygons used in the distribution mapping process. New information During an IUCN Red List Gulf of Mexico Fishes Assessment Workshop held at The Harte Research Institute for Gulf of Mexico Studies, a session included an open discussion on the topic of including other sources of species occurrence data. During the last decade, advances in portable electronic devices and applications enable 'citizen scientists' to record images, location and data about species sightings, and submit that data to larger species databases. These applications typically generate point data. Attendees of the workshop expressed an interest in how that data could be incorporated into existing datasets, how best to ascertain the quality and value of that data, and what other alternate data sources are available. This paper addresses those issues, and provides recommendations to ensure quality data use. PMID:25941453

  18. Mariner Venus-Mercury 1973 project. Volume 2: Extended mission-Mercury 2 and 3 encounters

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The Mariner Venus/Mercury 1973 mission operations Extended Mission is described. The activities are summarized from shortly after Mercury I through the end of mission. The operational activities are reported by Mission Operations Systems functions providing a brief summary from each discipline. Based on these experiences recommendations for future projects are made.

  19. Respiratory Kinetics of Marine Bacteria Exposed to Decreasing Oxygen Concentrations

    PubMed Central

    Gong, Xianzhe; Garcia-Robledo, Emilio; Schramm, Andreas

    2015-01-01

    During aerobic respiration, microorganisms consume oxygen (O2) through the use of different types of terminal oxidases which have a wide range of affinities for O2. The Km values for O2 of these enzymes have been determined to be in the range of 3 to 200 nmol liter−1. In this study, we examined the time course of development of aerobic respiratory kinetics of four marine bacterial species (Dinoroseobacter shibae, Roseobacter denitrificans, Idiomarina loihiensis, and Marinobacter daepoensis) during exposure to decreasing O2 concentrations. The genomes of all four species have genes for both high-affinity and low-affinity terminal oxidases. The respiration rate of the bacteria was measured by the use of extremely sensitive optical trace O2 sensors (range, 1 to 1,000 nmol liter−1). Three of the four isolates exhibited apparent Km values of 30 to 60 nmol liter−1 when exposed to submicromolar O2 concentrations, but a decrease to values below 10 nmol liter−1 was observed when the respiration rate per cell was lowered and the cell size was decreased due to starvation. The fourth isolate did not reach a low respiration rate per cell during starvation and exhibited apparent Km values of about 20 nmol liter−1 throughout the experiment. The results clearly demonstrate not only that enzyme kinetics may limit O2 uptake but also that even individual cells may be diffusion limited and that this diffusion limitation is the most pronounced at high respiration rates. A decrease in cell size by starvation, due to limiting organic carbon, and thereby more efficient diffusion uptake may also contribute to lower apparent Km values. PMID:26682857

  20. Respiratory Kinetics of Marine Bacteria Exposed to Decreasing Oxygen Concentrations.

    PubMed

    Gong, Xianzhe; Garcia-Robledo, Emilio; Schramm, Andreas; Revsbech, Niels Peter

    2016-03-01

    During aerobic respiration, microorganisms consume oxygen (O2) through the use of different types of terminal oxidases which have a wide range of affinities for O2. The Km values for O2 of these enzymes have been determined to be in the range of 3 to 200 nmol liter(-1). In this study, we examined the time course of development of aerobic respiratory kinetics of four marine bacterial species (Dinoroseobacter shibae, Roseobacter denitrificans, Idiomarina loihiensis, and Marinobacter daepoensis) during exposure to decreasing O2 concentrations. The genomes of all four species have genes for both high-affinity and low-affinity terminal oxidases. The respiration rate of the bacteria was measured by the use of extremely sensitive optical trace O2 sensors (range, 1 to 1,000 nmol liter(-1)). Three of the four isolates exhibited apparent Km values of 30 to 60 nmol liter(-1) when exposed to submicromolar O2 concentrations, but a decrease to values below 10 nmol liter(-1) was observed when the respiration rate per cell was lowered and the cell size was decreased due to starvation. The fourth isolate did not reach a low respiration rate per cell during starvation and exhibited apparent Km values of about 20 nmol liter(-1) throughout the experiment. The results clearly demonstrate not only that enzyme kinetics may limit O2 uptake but also that even individual cells may be diffusion limited and that this diffusion limitation is the most pronounced at high respiration rates. A decrease in cell size by starvation, due to limiting organic carbon, and thereby more efficient diffusion uptake may also contribute to lower apparent Km values. PMID:26682857

  1. Habitat partitioning of marine benthic denitrifier communities in response to oxygen availability.

    PubMed

    Wittorf, Lea; Bonilla-Rosso, Germán; Jones, Christopher M; Bäckman, Ola; Hulth, Stefan; Hallin, Sara

    2016-08-01

    Denitrification is of global significance for the marine nitrogen budget and the main process for nitrogen loss in coastal sediments. This facultative anaerobic respiratory pathway is modular in nature and the final step, the reduction of nitrous oxide (N2 O), is performed by microorganisms with a complete denitrification pathway as well as those only capable of N2 O reduction. Fluctuating oxygen availability is a significant driver of denitrification in sediments, but the effects on the overall N2 O-reducing community that ultimately controls the emission of N2 O from marine sediments is not well known. To investigate the effects of different oxygen regimes on N2 O reducing communities, coastal marine surface sediment was incubated in microcosms under oxic, anoxic or oscillating oxygen conditions in the overlying water for 137 days. Quantification of the genetic potential for denitrification, anammox and respiratory ammonification indicated that denitrification supported nitrogen removal in these sediments. Furthermore, denitrifiers with a complete pathway were identified as the dominant community involved in N2 O reduction, rather than organisms that are only N2 O reducers. Specific lineages within each group were associated with different oxygen regimes suggesting that oxygen availability in the overlying water is associated with habitat partitioning of N2 O reducers in coastal marine surface sediments. PMID:26929183

  2. Phanerozoic atmosphere oxygen cycles revealed by trace elements in marine pyrite

    NASA Astrophysics Data System (ADS)

    Large, R. R.; Halpin, J.

    2014-12-01

    It is generally accepted that oxygen in the atmosphere rose in two major steps at around 2.4-2.2 and 0.7-0.5 billion years ago. The variation in atmosphere oxygen over the last 500 million years, is considered to have been relatively minor by comparison. Sedimentary pyrite from marine shales efficiently captures many trace elements from the oceans, providing a novel proxy for seawater chemistry. Here we use temporal changes in the selenium and cobalt content of Phanerozoic marine pyrite, coupled with the 87Sr/86Sr ratio in marine carbonate, to argue for five dramatic pO2 cycles, each starting with a period of oxygenation, followed by a period of de-oxygenation. The selenium proxy is based on the premise that increased erosion of continental rocks leads to the release of selenium as both the selenate and selenite species. Under neutral to alkaline, oxygenated conditions the selenate species remains highly soluble, where it can be readily transported via river systems to the ocean. Cobalt on the other hand becomes less soluble under increasing pO2 as the oxidized species Co2+ and CoO are immobilised by Fe and Mn oxyhydroxides, that form during weathering. Thus variations in the Se and Co composition of marine pyrite enable us to propose a new oxygenation proxy; the ratio Se/Co, which increases in marine pyrite during periods of increasing pO2 (oxygenation) and decreases during periods of decreasing pO2 (deoxygenation). The first half of each of the five Phanerozoic pO2 cycles involves an increase in atmosphere/ocean oxygenation driven initially by supercontinent dispersal, increased continental erosion and nutrient trace element flux to the oceans. Increased marine productivity leads to carbon and sulphur sequestration, producing metalliferous black shales, and further drives oxygenation to the peak of the cycle. The cycle downside suggests decreasing oxidative erosion and nutrient delivery, resulting in a drop in productivity. Continued drawdown of ocean trace

  3. Observations of Europa's Extended Atmosphere and Torus; Oxygen and the Discovery of Hydrogen

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Shemansky, D. E.; Hendrix, A. R.

    2003-05-01

    Cassini UVIS observed Europa in January 2001. With 0.25 mrad resolution we identify Europa as a point source of e- + O2 oxygen emission. We also recognize a spatially broader source apparently produced by electron and photon excitation of atomic oxygen. This second emission source may be indicative of a torus of atomic oxygen. Atomic hydrogen emission suggests a strong peak at Europa merged with a more complex spatially extended distribution, partially from a different source. UVIS observed Europa and its environment with 0.48 nm spectral resolution. The UVIS slit, with 64 spatial pixels, was oriented perpendicular to Jupiter's equatorial plane. The total extent of the slit was such that spatial coverage extended well beyond the orbital planes of the Galilean satellites. The total integration time in the January 6 observation was 17,000 seconds, and on January 12 integration time was 41,000 seconds. The UVIS data clearly shows the 130.4 nm and 135.6 nm emission features first detected by HST and attributed by Hall et al (1995) to a bound O2 atmosphere at Europa. These are actually atomic oxygen emission lines and using the intrinsic capability of the UVIS instrument we are able to identify both a closely bound O2 component to Europa's atmosphere and an extended atomic oxygen component. We will discuss the compatibility of our results with the torus of neutrals in Europa's orbit first reported by Mauk et al (2003) using the Cassini INCA instrument. We can identify the composition of this torus to be almost entirely hydrogen. Atomic oxygen forms a very minor component. We find the torus to be much smaller in extent than they reported, with a diameter of just 0.3 Jovian radii. Part of this work was performed at the Jet Propulsion Laboratory / California Institute of Technology.

  4. Extended time observations of California marine stratocumulus clouds from GOES for July 1983-1987

    NASA Technical Reports Server (NTRS)

    Minnis, Patrick; Harrison, Edwin F.; Young, David F.

    1990-01-01

    One of the goals of the First ISCCP Regional Experiment (FIRE) is to relate the relatively small scale (spatial and temporal) Intensive Field Observations (IFO) to larger time and space domains embodied in the Extended Time Observations (ETO) phase of the experiment. The data analyzed as part of the ETO are to be used to determine some climatological features of the limited area which encompasses the Marine Stratocumulus IFO which took place between 29 June and 19 July 1987 off the coast of southern California.

  5. DETERMINATION OF LETHAL DISSOLVED OXYGEN LEVELS FOR SELECTED MARINE AND ESTUARINE FISHES, CRUSTACEANS AND A BIVALVE

    EPA Science Inventory

    The objective of this study was to provide a database of the incipient lethal concentrations for reduced dissolved oxygen (DO) for selected marine and estuarine species including 12 species of fish, 9 crustaceans, and 1 bivalve. All species occur in the Virginian Province, USA, w...

  6. Measurement in a marine environment using low cost sensors of temperature and dissolved oxygen

    USGS Publications Warehouse

    Godshall, F.A.; Cory, R.L.; Phinney, D.E.

    1974-01-01

    Continuous records of physical parameters of the marine environment are difficult as well as expensive to obtain. This paper describes preliminary results of an investigative program with the purpose of developing low cost time integrating measurement and averaging devices for water temperature and dissolved oxygen. Measurements were made in an estuarine area of the Chesapeake Bay over two week periods. With chemical thermometers average water temperature for the two week period was found to be equal to average water temperature measured with thermocouples plus or minus 1.0 C. The slow diffusion of oxygen through the semipermiable sides of plastic bottles permitted the use of water filled bottles to obtain averaged oxygen measurements. Oxygen measurements for two week averaging times using 500 ml polyethylene bottles were found to vary from conventionally measured and averaged dissolved oxygen by about 1.8 mg/l. ?? 1974 Estuarine Research Federation.

  7. Oxygen limitations on marine animal distributions and the collapse of epibenthic community structure during shoaling hypoxia.

    PubMed

    Chu, Jackson W F; Tunnicliffe, Verena

    2015-08-01

    Deoxygenation in the global ocean is predicted to induce ecosystem-wide changes. Analysis of multidecadal oxygen time-series projects the northeast Pacific to be a current and future hot spot of oxygen loss. However, the response of marine communities to deoxygenation is unresolved due to the lack of applicable data on component species. We repeated the same benthic transect (n = 10, between 45 and 190 m depths) over 8 years in a seasonally hypoxic fjord using remotely operated vehicles equipped with oxygen sensors to establish the lower oxygen levels at which 26 common epibenthic species can occur in the wild. By timing our surveys to shoaling hypoxia events, we show that fish and crustacean populations persist even in severe hypoxia (<0.5 mL L(-1) ) with no mortality effects but that migration of mobile species occurs. Consequently, the immediate response to hypoxia expansion is the collapse of community structure; normally partitioned distributions of resident species coalesced and localized densities increased. After oxygen renewal and formation of steep oxygen gradients, former ranges re-established. High frequency data from the nearby VENUS subsea observatory show the average oxygen level at our site declined by ~0.05 mL L(-1) year(-1) over the period of our study. The increased annual duration of the hypoxic (<1.4 mL L(-1) ) and severely hypoxic periods appears to reflect the oxygen dynamics demonstrated in offshore source waters and the adjacent Strait of Georgia. Should the current trajectory of oxygen loss continue, community homogenization and reduced suitable habitat may become the dominant state of epibenthic systems in the northeast Pacific. In situ oxygen occurrences were not congruent with lethal and sublethal hypoxia thresholds calculated across the literature for major taxonomic groups indicating that research biases toward laboratory studies on Atlantic species are not globally applicable. Region-specific hypoxia thresholds are necessary to

  8. Evaluating the Impact of Changes in Oceanic Dissolved Oxygen on Marine Nitrous Oxide

    NASA Astrophysics Data System (ADS)

    Suntharalingam, Parvadha; Buitenhuis, Erik; Schmidtko, Sunke; Andrews, Oliver; LeQuere, Corinne

    2013-04-01

    Emissions of the greenhouse gas nitrous-oxide (N2O) from oceanic oxygen minimum zones (OMZs) in the Equatorial Pacific and Northwest Indian Ocean are believed to provide a significant portion of the global oceanic flux to the atmosphere. Mechanisms of marine N2O production and consumption in these regions display significant sensitivity to ambient oxygen, with high yields at low oxygen levels (O2 < 50 micromol/L), and N2O depletion via denitrification in anoxic zones. These OMZ regions display large gradients in sub-surface N2O, and high rates of N2O turnover that far exceed those observed in the open ocean. Recent studies have suggested that possible expansion of oceanic OMZs in a warming climate, could lead to significant changes in N2O emissions from these zones. In this analysis we employ a global ocean biogeochemistry model (NEMO-PlankTOM), which includes representation of the marine N2O cycle, to explore the impact of changes in dissolved oxygen on the ocean-atmosphere N2O flux. We focus on the period 1960-2000, and evaluate the impact of estimated changes in ocean oxygen from two alternative sources : (a) the observationally-based upper-ocean oxygen distributions and trends of Stramma et al. [2012]; (b) simulated oxygen distributions and temporal variations from a set of CMIP5 Earth System models. We will inter-compare the oceanic N2O estimates derived from these alternative scenarios of ocean de-oxygenation. We will also discuss the implications of our results for the ability to reliably predict changes in N2O emissions under potential expansion of oceanic OMZs, particularly in view of the recently noted discrepancies between observed and modeled trends in oceanic oxygen by Stramma et al. [2012].

  9. A novel approach to the assess biotic oxygen consumption in marine sediment communities

    NASA Astrophysics Data System (ADS)

    Baranov, Victor; Queiros, Ana; Widdicombe, Stephen; Stephens, Nick; Lessin, Gennadi; Krause, Stefan; Lewandowski, Joerg

    2016-04-01

    Bioturbation , the mixing of the sediment matrix by burrowing animals impacts sediment metabolism, including respiration through redistribution of particulate organics, changes in bacterial biota diversity and acitivity, as well as via burrowing fauna's own metabolism. Bioturbation, reflecting faunal activity, is also a proxy for the general sedimentary ecosystem health, and can be impacted by many of emerging marine environmental issues such as ocean acidification, warming and the occurrence of heat waves. Sedimentary oxygen consumption is often taken as a proxy for the activity of bioturbating fauna, but determining baselines can be difficult because of the confounding effects of other fauna and microbes present in sediments, as well as irnorganic processes that consume oxygen. Limitations therefore exist in current methodologies, and numerous confounding factors are hampering progress in this area. Here, we present novel method for the assessment of sediment respiration which is expected to be affected only by the biogenic oxygen consumption (namely aerobic respiration). As long as tracer reduction "immune" to inorganic oxygen consumption, so that measurements using this method can be used, alongside traditional methods, to decouple biological respiration from inorganic oxygen consumption reactions. The tracer is easily detectable, non-toxic and can be applied in systems with constant oxygen supply. The latter allow for incubation without the need to to work with unsealed experimental units, bringing procedural advantage over traditional methods. Consequently assessed bioturbating fauna is not exposed to hypoxia and additional stress. Here, we had applied system for the first time to investigate impacts of a common North-Atlantic bioturbator, the brittle star Amphiura filiformis, - on respiration of marine sediments. Two series of experiments were conducted with animals and sediment collected from Cawsand Bay, Plymouth, UK Preliminary results show that tracer

  10. Extended period of K/T boundary mass extinction in the marine realm

    NASA Technical Reports Server (NTRS)

    Keller, G.

    1988-01-01

    The Cretaceous/Tertiary (K/T) boundary mass extinction has been widely recognized as a nearly instantaneous catastrophy among marine plankton such as foraminifera. However, the suddenness of this extinction event may have been overemphasized because most pelagic K/T boundary sequences are stratigraphically incomplete and generally lack the earliest Tertiary (Zones P0 and P1a) either due to carbonate dissolution and/or non-deposition. Stratigraphically complete sections appear to be restricted to continental shelf regions with high sedimentation rates and deposition well above the CCD. Such sections have been recovered from El Kef, Tunisia (1) and Brazos River, Texas. Quantitative foraminiferal analysis of these sections indicate an extinction pattern beginning below the K/T boundary and ending above the boundary. These data imply that the mass extinction event was not geologically instantaneous, but occurred over an extended period of time. Evidence supporting this conclusion is discussed.

  11. Think laterally: horizontal gene transfer from symbiotic microbes may extend the phenotype of marine sessile hosts

    PubMed Central

    Degnan, Sandie M.

    2014-01-01

    Since the origin of the animal kingdom, marine animals have lived in association with viruses, prokaryotes and unicellular eukaryotes, often as symbionts. This long and continuous interaction has provided ample opportunity not only for the evolution of intimate interactions such as sharing of metabolic pathways, but also for horizontal gene transfer (HGT) of non-metazoan genes into metazoan genomes. The number of demonstrated cases of inter-kingdom HGT is currently small, such that it is not yet widely appreciated as a significant player in animal evolution. Sessile marine invertebrates that vertically inherit bacterial symbionts, that have no dedicated germ line, or that bud or excise pluripotent somatic cells during their life history may be particularly receptive to HGT from their symbionts. Closer scrutiny of the growing number of genomes being accrued for these animals may thus reveal HGT as a regular source of novel variation that can function to extend the host phenotype metabolically, morphologically, or even behaviorally. Taxonomic identification of symbionts will help to address the intriguing question of whether past HGT events may constrain contemporary symbioses. PMID:25477875

  12. Effect of shortening kraft pulping integrated with extended oxygen delignification on biorefinery process performance of eucalyptus.

    PubMed

    Li, Jing; Zhang, Chunyun; Hu, Huichao; Chai, Xin-Sheng

    2016-02-01

    The aim of this work was to study the impact of shortening kraft pulping (KP) process integrated with extended oxygen delignification (OD) on the biorefinery process performance of eucalyptus. Data showed that using kraft pulps with high kappa number could improve the delignification efficiency of OD, reduce hexenuronic acid formation in kraft pulps. Pulp viscosity for a target kappa number of ∼10 was comparable to that obtained from conventional KP and OD process. The energy and alkali consumption in the integrated biorefinery process could be optimized when using a KP pulp with kappa number of ∼27. The process could minimize the overall methanol formation, but greater amounts of carbonate and oxalate were formed. The information from this study will be helpful to the future implementation of short-time KP integrated with extended OD process in actual pulp mill applications for biorefinery, aiming at further improvement in the biorefinery effectiveness of hardwood. PMID:26706725

  13. Osseous skeletal material and fish scales in marine sediments under the oxygen minimum zone off northern and central Chile

    NASA Astrophysics Data System (ADS)

    Milessi, Andrés C.; Sellanes, Javier; Gallardo, Víctor A.; Lange, Carina B.

    2005-08-01

    The significance of whale falls for the study of the biogeography, evolution and biodiversity of deep-sea biota has been recently recognized by international programs since large carcasses are known to give rise to biogenic chemosynthetic ecosystems. However, the plain accumulation of smaller bone material in the shallower settings of the continental shelf and upper slope under the hypoxic conditions of the Oxygen Minimum Zone (OMZ), has received much less attention. Here we describe new findings of skeletal material and fish scales in marine sediments under the OMZ off northern and central Chile which, combined with previous reports for the study area, lead us to suggest the existence of a band in the benthos of accumulation of bones and scales extending at least twenty degrees in latitude (18-38° S). Future studies should focus on the characterization of biotic communities living upon these resources in order to elucidate their peculiarities and importance in the Eastern South Pacific.

  14. Climate change affects marine fishes through the oxygen limitation of thermal tolerance.

    PubMed

    Pörtner, Hans O; Knust, Rainer

    2007-01-01

    A cause-and-effect understanding of climate influences on ecosystems requires evaluation of thermal limits of member species and of their ability to cope with changing temperatures. Laboratory data available for marine fish and invertebrates from various climatic regions led to the hypothesis that, as a unifying principle, a mismatch between the demand for oxygen and the capacity of oxygen supply to tissues is the first mechanism to restrict whole-animal tolerance to thermal extremes. We show in the eelpout, Zoarces viviparus, a bioindicator fish species for environmental monitoring from North and Baltic Seas (Helcom), that thermally limited oxygen delivery closely matches environmental temperatures beyond which growth performance and abundance decrease. Decrements in aerobic performance in warming seas will thus be the first process to cause extinction or relocation to cooler waters. PMID:17204649

  15. Inhibition of nitrogenase by oxygen in marine cyanobacteria controls the global nitrogen and oxygen cycles

    NASA Astrophysics Data System (ADS)

    Berman-Frank, I.; Chen, Y.-B.; Gerchman, Y.; Dismukes, G. C.; Falkowski, P. G.

    2005-03-01

    Cyanobacterial N2-fixation supplies the vast majority of biologically accessible inorganic nitrogen to nutrient-poor aquatic ecosystems. The process, catalyzed by the heterodimeric protein complex, nitrogenase, is thought to predate that of oxygenic photosynthesis. Remarkably, while the enzyme plays such a critical role in Earth's biogeochemical cycles, the activity of nitrogenase in cyanobacteria is markedly inhibited in vivo at a post-translational level by the concentration of O2 in the contemporary atmosphere leading to metabolic and biogeochemical inefficiency in N2 fixation. We illustrate this crippling effect with data from Trichodesmium spp. an important contributor of "new nitrogen" to the world's subtropical and tropical oceans. The enzymatic inefficiency of nitrogenase imposes a major elemental taxation on diazotrophic cyanobacteria both in the costs of protein synthesis and for scarce trace elements, such as iron. This restriction has, in turn, led to a global limitation of fixed nitrogen in the contemporary oceans and provides a strong biological control on the upper bound of oxygen concentration in Earth's atmosphere.

  16. Using fluorochemical as oxygen carrier to enhance the growth of marine microalga Nannochloropsis oculata.

    PubMed

    Lee, Yu-Hsiang; Yeh, Yu-Ling; Lin, Keng-Hsien; Hsu, Yu-Chih

    2013-08-01

    The commercial value of marine Nannochloropsis oculata has been recognized due to its high content of eicosapentaenoic acid (>50% w/w). To make it as a profitable bioresource, one of the most desirable goals is to develop a quality-controlled, cost-effective, and large-scale photobioreactor for N. oculata growth. Generally, closed culture system can offer many advantages over open system such as small space requirement, controllable process and low risk of contamination. However, oxygen accumulation is often a detrimental factor for enclosed microalgal culture that has seriously hampered the development of microalga-related industries. In this study, we proposed to use fluorochemical as oxygen carrier to overcome the challenge where four liquid fluorochemicals namely perfluorooctyl bromide, perfluorodecalin, methoxynonafluorobutane, and ethoxynonafluorobutane were investigated separately. Our results showed that the microalgal proliferation with different fluorinated liquids was similar and comparable to the culture without a fluorochemical. When cultured in the photobioreactor with 60% oxygen atmosphere, the N. oculata can grow up in all the fluorochemical photobioreactors, but completely inhibited in the chamber without a fluorochemical. Moreover, the perfluorooctyl bromide system exhibited the most robust efficacy of oxygen removal in the culture media (perfluorooctyl bromide > perfluorodecalin > methoxynonafluorobutane > ethoxynonafluorobutane), and yielded a >3-fold increase of biomass production after 5 days. In summary, the developed fluorochemical photobioreactors offer a feasible means for N. oculata growth in closed and large-scale setting without effect of oxygen inhibition. PMID:23178985

  17. Meta-omic signatures of microbial metal and nitrogen cycling in marine oxygen minimum zones

    PubMed Central

    Glass, Jennifer B.; Kretz, Cecilia B.; Ganesh, Sangita; Ranjan, Piyush; Seston, Sherry L.; Buck, Kristen N.; Landing, William M.; Morton, Peter L.; Moffett, James W.; Giovannoni, Stephen J.; Vergin, Kevin L.; Stewart, Frank J.

    2015-01-01

    Iron (Fe) and copper (Cu) are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO3−, NO2−, Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metagenomes and 9 metatranscriptomes from Eastern Tropical North and South Pacific oxygen minimum zones and 7 metagenomes from the Bermuda Atlantic Time-series Station. Dissolved Fe concentrations increased sharply at upper oxic-anoxic transition zones, with the highest Fe:Cu molar ratio (1.8) occurring at the anoxic core of the Eastern Tropical North Pacific oxygen minimum zone and matching the predicted maximum ratio based on data from diverse ocean sites. The relative abundance of genes encoding Fe-binding proteins was negatively correlated with O2, driven by significant increases in genes encoding Fe-proteins involved in dissimilatory nitrogen metabolisms under anoxia. Transcripts encoding cytochrome c oxidase, the Fe- and Cu-containing terminal reductase in aerobic respiration, were positively correlated with O2 content. A comparison of the taxonomy of genes encoding Fe- and Cu-binding vs. bulk proteins in OMZs revealed that Planctomycetes represented a higher percentage of Fe genes while Thaumarchaeota represented a higher percentage of Cu genes, particularly at oxyclines. These results are broadly consistent with higher relative abundance of genes encoding Fe-proteins in the genome of a marine planctomycete vs. higher relative abundance of genes encoding Cu-proteins in the genome of a marine thaumarchaeote. These findings highlight the importance of metalloenzymes for microbial processes in oxygen minimum zones and suggest preferential Cu use in oxic habitats with Cu > Fe vs. preferential Fe use in anoxic niches with Fe > Cu. PMID:26441925

  18. Confounding effects of oxygen and temperature on the TEX86 signature of marine Thaumarchaeota

    PubMed Central

    Qin, Wei; Carlson, Laura T.; Armbrust, E. Virginia; Devol, Allan H.; Moffett, James W.; Stahl, David A.; Ingalls, Anitra E.

    2015-01-01

    Marine ammonia-oxidizing archaea (AOA) are among the most abundant of marine microorganisms, spanning nearly the entire water column of diverse oceanic provinces. Historical patterns of abundance are preserved in sediments in the form of their distinctive glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids. The correlation between the composition of GDGTs in surface sediment and the overlying annual average sea surface temperature forms the basis for a paleotemperature proxy (TEX86) that is used to reconstruct surface ocean temperature as far back as the Middle Jurassic. However, mounting evidence suggests that factors other than temperature could also play an important role in determining GDGT distributions. We here use a study set of four marine AOA isolates to demonstrate that these closely related strains generate different TEX86–temperature relationships and that oxygen (O2) concentration is at least as important as temperature in controlling TEX86 values in culture. All of the four strains characterized showed a unique membrane compositional response to temperature, with TEX86-inferred temperatures varying as much as 12 °C from the incubation temperatures. In addition, both linear and nonlinear TEX86–temperature relationships were characteristic of individual strains. Increasing relative abundance of GDGT-2 and GDGT-3 with increasing O2 limitation, at the expense of GDGT-1, led to significant elevations in TEX86-derived temperature. Although the adaptive significance of GDGT compositional changes in response to both temperature and O2 is unclear, this observation necessitates a reassessment of archaeal lipid-based paleotemperature proxies, particularly in records that span low-oxygen events or underlie oxygen minimum zones. PMID:26283385

  19. Meta-omic signatures of microbial metal and nitrogen cycling in marine oxygen minimum zones.

    PubMed

    Glass, Jennifer B; Kretz, Cecilia B; Ganesh, Sangita; Ranjan, Piyush; Seston, Sherry L; Buck, Kristen N; Landing, William M; Morton, Peter L; Moffett, James W; Giovannoni, Stephen J; Vergin, Kevin L; Stewart, Frank J

    2015-01-01

    Iron (Fe) and copper (Cu) are essential cofactors for microbial metalloenzymes, but little is known about the metalloenyzme inventory of anaerobic marine microbial communities despite their importance to the nitrogen cycle. We compared dissolved O2, NO[Formula: see text], NO[Formula: see text], Fe and Cu concentrations with nucleic acid sequences encoding Fe and Cu-binding proteins in 21 metagenomes and 9 metatranscriptomes from Eastern Tropical North and South Pacific oxygen minimum zones and 7 metagenomes from the Bermuda Atlantic Time-series Station. Dissolved Fe concentrations increased sharply at upper oxic-anoxic transition zones, with the highest Fe:Cu molar ratio (1.8) occurring at the anoxic core of the Eastern Tropical North Pacific oxygen minimum zone and matching the predicted maximum ratio based on data from diverse ocean sites. The relative abundance of genes encoding Fe-binding proteins was negatively correlated with O2, driven by significant increases in genes encoding Fe-proteins involved in dissimilatory nitrogen metabolisms under anoxia. Transcripts encoding cytochrome c oxidase, the Fe- and Cu-containing terminal reductase in aerobic respiration, were positively correlated with O2 content. A comparison of the taxonomy of genes encoding Fe- and Cu-binding vs. bulk proteins in OMZs revealed that Planctomycetes represented a higher percentage of Fe genes while Thaumarchaeota represented a higher percentage of Cu genes, particularly at oxyclines. These results are broadly consistent with higher relative abundance of genes encoding Fe-proteins in the genome of a marine planctomycete vs. higher relative abundance of genes encoding Cu-proteins in the genome of a marine thaumarchaeote. These findings highlight the importance of metalloenzymes for microbial processes in oxygen minimum zones and suggest preferential Cu use in oxic habitats with Cu > Fe vs. preferential Fe use in anoxic niches with Fe > Cu. PMID:26441925

  20. Confounding effects of oxygen and temperature on the TEX86 signature of marine Thaumarchaeota.

    PubMed

    Qin, Wei; Carlson, Laura T; Armbrust, E Virginia; Devol, Allan H; Moffett, James W; Stahl, David A; Ingalls, Anitra E

    2015-09-01

    Marine ammonia-oxidizing archaea (AOA) are among the most abundant of marine microorganisms, spanning nearly the entire water column of diverse oceanic provinces. Historical patterns of abundance are preserved in sediments in the form of their distinctive glycerol dibiphytanyl glycerol tetraether (GDGT) membrane lipids. The correlation between the composition of GDGTs in surface sediment and the overlying annual average sea surface temperature forms the basis for a paleotemperature proxy (TEX86) that is used to reconstruct surface ocean temperature as far back as the Middle Jurassic. However, mounting evidence suggests that factors other than temperature could also play an important role in determining GDGT distributions. We here use a study set of four marine AOA isolates to demonstrate that these closely related strains generate different TEX86-temperature relationships and that oxygen (O2) concentration is at least as important as temperature in controlling TEX86 values in culture. All of the four strains characterized showed a unique membrane compositional response to temperature, with TEX86-inferred temperatures varying as much as 12 °C from the incubation temperatures. In addition, both linear and nonlinear TEX86-temperature relationships were characteristic of individual strains. Increasing relative abundance of GDGT-2 and GDGT-3 with increasing O2 limitation, at the expense of GDGT-1, led to significant elevations in TEX86-derived temperature. Although the adaptive significance of GDGT compositional changes in response to both temperature and O2 is unclear, this observation necessitates a reassessment of archaeal lipid-based paleotemperature proxies, particularly in records that span low-oxygen events or underlie oxygen minimum zones. PMID:26283385

  1. Extended evaluation of polymeric and lipophilic sorbents for passive sampling of marine toxins.

    PubMed

    Zendong, Zita; Herrenknecht, Christine; Abadie, Eric; Brissard, Charline; Tixier, Céline; Mondeguer, Florence; Séchet, Véronique; Amzil, Zouher; Hess, Philipp

    2014-12-01

    has significantly extended the range of sorbents for passive sampling of marine toxins. In particular, sorbents were included that had previously been evaluated for polyhalogenated contaminants, pharmaceuticals, phytochemicals or veterinary residues. Moreover, this study has for the first time demonstrated the usefulness of the polymeric Oasis HLB and Strata-X sorbents in laboratory and field studies for various microalgal toxins. PMID:24709758

  2. When surfacers do not dive: multiple significance of extended surface times in marine turtles.

    PubMed

    Hochscheid, S; Bentivegna, F; Hamza, A; Hays, G C

    2010-04-01

    Marine turtles spend more than 90% of their life underwater and have been termed surfacers as opposed to divers. Nonetheless turtles have been reported occasionally to float motionless at the surface but the reasons for this behaviour are not clear. We investigated the location, timing and duration of extended surface times (ESTs) in 10 free-ranging loggerhead turtles (Caretta caretta) and the possible relationship to water temperature and diving activity recorded via satellite relay data loggers for 101-450 days. For one turtle that dived only in offshore areas, ESTs contributed 12% of the time whereas for the other turtles ESTs contributed 0.4-1.8% of the time. ESTs lasted on average 90 min but were mostly infrequent and irregular, excluding the involvement of a fundamental regulatory function. However, 82% of the ESTs occurred during daylight, mostly around noon, suggesting a dependence on solar radiation. For three turtles, there was an appreciable (7 degrees C to 10.5 degrees C) temperature decrease with depth for dives during periods when ESTs occurred frequently, suggesting a re-warming function of EST to compensate for decreased body temperatures, possibly to enhance digestive efficiency. A positive correlation between body mass and EST duration supported this explanation. By contrast, night-active turtles that exceeded their calculated aerobic dive limits in 7.6-16% of the dives engaged in nocturnal ESTs, probably for lactate clearance. This is the first evidence that loggerhead turtles may refrain from diving for at least two reasons, either to absorb solar radiation or to recover from anaerobic activity. PMID:20348345

  3. The Extended Oxygen Window Concept for Programming Saturation Decompressions Using Air and Nitrox.

    PubMed

    Kot, Jacek; Sicko, Zdzislaw; Doboszynski, Tadeusz

    2015-01-01

    Saturation decompression is a physiological process of transition from one steady state, full saturation with inert gas at pressure, to another one: standard conditions at surface. It is defined by the borderline condition for time spent at a particular depth (pressure) and inert gas in the breathing mixture (nitrogen, helium). It is a delicate and long lasting process during which single milliliters of inert gas are eliminated every minute, and any disturbance can lead to the creation of gas bubbles leading to decompression sickness (DCS). Most operational procedures rely on experimentally found parameters describing a continuous slow decompression rate. In Poland, the system for programming of continuous decompression after saturation with compressed air and nitrox has been developed as based on the concept of the Extended Oxygen Window (EOW). EOW mainly depends on the physiology of the metabolic oxygen window--also called inherent unsaturation or partial pressure vacancy--but also on metabolism of carbon dioxide, the existence of water vapor, as well as tissue tension. Initially, ambient pressure can be reduced at a higher rate allowing the elimination of inert gas from faster compartments using the EOW concept, and maximum outflow of nitrogen. Then, keeping a driving force for long decompression not exceeding the EOW allows optimal elimination of nitrogen from the limiting compartment with half-time of 360 min. The model has been theoretically verified through its application for estimation of risk of decompression sickness in published systems of air and nitrox saturation decompressions, where DCS cases were observed. Clear dose-reaction relation exists, and this confirms that any supersaturation over the EOW creates a risk for DCS. Using the concept of the EOW, 76 man-decompressions were conducted after air and nitrox saturations in depth range between 18 and 45 meters with no single case of DCS. In summary, the EOW concept describes physiology of

  4. The Extended Oxygen Window Concept for Programming Saturation Decompressions Using Air and Nitrox

    PubMed Central

    Kot, Jacek; Sicko, Zdzislaw

    2015-01-01

    Saturation decompression is a physiological process of transition from one steady state, full saturation with inert gas at pressure, to another one: standard conditions at surface. It is defined by the borderline condition for time spent at a particular depth (pressure) and inert gas in the breathing mixture (nitrogen, helium). It is a delicate and long lasting process during which single milliliters of inert gas are eliminated every minute, and any disturbance can lead to the creation of gas bubbles leading to decompression sickness (DCS). Most operational procedures rely on experimentally found parameters describing a continuous slow decompression rate. In Poland, the system for programming of continuous decompression after saturation with compressed air and nitrox has been developed as based on the concept of the Extended Oxygen Window (EOW). EOW mainly depends on the physiology of the metabolic oxygen window—also called inherent unsaturation or partial pressure vacancy—but also on metabolism of carbon dioxide, the existence of water vapor, as well as tissue tension. Initially, ambient pressure can be reduced at a higher rate allowing the elimination of inert gas from faster compartments using the EOW concept, and maximum outflow of nitrogen. Then, keeping a driving force for long decompression not exceeding the EOW allows optimal elimination of nitrogen from the limiting compartment with half-time of 360 min. The model has been theoretically verified through its application for estimation of risk of decompression sickness in published systems of air and nitrox saturation decompressions, where DCS cases were observed. Clear dose-reaction relation exists, and this confirms that any supersaturation over the EOW creates a risk for DCS. Using the concept of the EOW, 76 man-decompressions were conducted after air and nitrox saturations in depth range between 18 and 45 meters with no single case of DCS. In summary, the EOW concept describes physiology of

  5. Laboratory and marine study of photoluminescent sensors of oxygen dissolved in seawater

    NASA Astrophysics Data System (ADS)

    Vlasov, V. L.; Konovalov, B. V.; Mosharov, V. E.; Radchenko, V. N.; Khanaev, S. A.; Khlebnikov, D. V.

    2010-02-01

    The laboratory and marine study of photoluminescent sensors developed at the TsAGI has been conducted to create a highly sensitivity gauge of the oxygen dissolved in seawater. The advantages of the photoluminescent gauge over the electrochemical ones are the following: zero sensitivity to electromagnetic fields, the pH of the water, and the hydrogen sulphide and ions of heavy metals in the water; zero oxygen consumption; and no need for the water to be pumped through the device. A breadboard model of the photoluminescent gauge with LED excitation of the luminescence has been built. The laboratory tests of the model demonstrated the accuracy of the gauge to be as high as 0.05 ml/1 in air at a response time of 0.3 s for 63% relaxation. Comparative field tests of the breadboard model and the SBE 43 electrochemical oxygen gauge (Sea-Bird Electronics Corp.) have shown good agreement of the estimates of the oxygen content in the water and clarified the prospects of model’s performance improvement.

  6. Oxygen Minimum Zones and the Marine Nitrogen Cycle: a Modeling Approach

    NASA Astrophysics Data System (ADS)

    Six, K. D.

    2014-12-01

    In the oxygen minimum zones (OMZ) of the global ocean fixed nitrogen is lost primarily by heterotrophic denitrification and anaerobic ammonium oxidation by nitrite (anammox). As it is projected that the OMZ expand in future due to global warming there is an urgent need to understand the controlling mechanisms of nitrogen loss within these regions. However, most Earth system models (ESM) rather have a poor representation of nitrogen related processes, primarily focusing only on nitrate. This simplification of the nitrogen cycle could contribute to the common model bias of too large and too intense OMZ in most ESM. We set up a more comprehensive marine N-cycle including interactions between nitrate, nitrite, ammonium, and organic material in the water column and the sediments in the framework of the global biogeochemical ocean model of the Max Planck Institute for Meteorology. We present a global marine nitrogen budget and discuss changes in the subsurface oxygen distributions. We find that the representation of a stepwise dissimilatory nitrate reduction to nitrite and ammonium improves the simulated OMZs and captures observed features like the secondary nitrite maximum.

  7. Mitochondrial reactive oxygen species: Do they extend or shorten animal lifespan?

    PubMed

    Sanz, Alberto

    2016-08-01

    Testing the predictions of the Mitochondrial Free Radical Theory of Ageing (MFRTA) has provided a deep understanding of the role of reactive oxygen species (ROS) and mitochondria in the aging process. However those data, which support MFRTA are in the majority correlative (e.g. increasing oxidative damage with age). In contrast the majority of direct experimental data contradict MFRTA (e.g. changes in ROS levels do not alter longevity as expected). Unfortunately, in the past, ROS measurements have mainly been performed using isolated mitochondria, a method which is prone to experimental artifacts and does not reflect the complexity of the in vivo process. New technology to study different ROS (e.g. superoxide or hydrogen peroxide) in vivo is now available; these new methods combined with state-of-the-art genetic engineering technology will allow a deeper interrogation of, where, when and how free radicals affect aging and pathological processes. In fact data that combine these new approaches, indicate that boosting mitochondrial ROS in lower animals is a way to extend both healthy and maximum lifespan. In this review, I discuss the latest literature focused on the role of mitochondrial ROS in aging, and how these new discoveries are helping to better understand the role of mitochondria in health and disease. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy, July 2-6, 2016', edited by Prof. Paolo Bernardi. PMID:26997500

  8. Planktonic marine iron oxidizers drive iron mineralization under low-oxygen conditions.

    PubMed

    Field, E K; Kato, S; Findlay, A J; MacDonald, D J; Chiu, B K; Luther, G W; Chan, C S

    2016-09-01

    Observations of modern microbes have led to several hypotheses on how microbes precipitated the extensive iron formations in the geologic record, but we have yet to resolve the exact microbial contributions. An initial hypothesis was that cyanobacteria produced oxygen which oxidized iron abiotically; however, in modern environments such as microbial mats, where Fe(II) and O2 coexist, we commonly find microaerophilic chemolithotrophic iron-oxidizing bacteria producing Fe(III) oxyhydroxides. This suggests that such iron oxidizers could have inhabited niches in ancient coastal oceans where Fe(II) and O2 coexisted, and therefore contributed to banded iron formations (BIFs) and other ferruginous deposits. However, there is currently little evidence for planktonic marine iron oxidizers in modern analogs. Here, we demonstrate successful cultivation of planktonic microaerophilic iron-oxidizing Zetaproteobacteria from the Chesapeake Bay during seasonal stratification. Iron oxidizers were associated with low oxygen concentrations and active iron redox cycling in the oxic-anoxic transition zone (<3 μm O2 , <0.2 μm H2 S). While cyanobacteria were also detected in this transition zone, oxygen concentrations were too low to support significant rates of abiotic iron oxidation. Cyanobacteria may be providing oxygen for microaerophilic iron oxidation through a symbiotic relationship; at high Fe(II) levels, cyanobacteria would gain protection against Fe(II) toxicity. A Zetaproteobacteria isolate from this site oxidized iron at rates sufficient to account for deposition of geologic iron formations. In sum, our results suggest that once oxygenic photosynthesis evolved, microaerophilic chemolithotrophic iron oxidizers were likely important drivers of iron mineralization in ancient oceans. PMID:27384464

  9. Marine phosphate oxygen isotopes and organic matter remineralization in the oceans

    PubMed Central

    Colman, Albert S.; Blake, Ruth E.; Karl, David M.; Fogel, Marilyn L.; Turekian, Karl K.

    2005-01-01

    We show that the isotopic composition of oxygen (δ18O) in dissolved inorganic phosphate (Pi) reveals the balance between Pi transport and biological turnover rates in marine ecosystems. Our δ18Op of Pi (δ18Op) measurements herein indicate the importance of cell lysis in the regeneration of Pi in the euphotic zone. Depth profiles of the δ18Op in the Atlantic and Pacific Oceans are near a temperature-dependent isotopic equilibrium with water. Small deviations from equilibrium below the thermocline suggest that P remineralization in the deep ocean is a byproduct of microbial carbon and energy requirements. However, isotope effects associated with phosphohydrolase enzymes involved in P remineralization are quite large and could potentially lead to significant disequilibration of Pi oxygen. The observed near equilibration of deep water Pi likely calls for continued slow rates of microbial uptake and release of Pi and/or extracellular pyrophosphatase-mediated oxygen exchange between water and Pi along the deep water flow path. PMID:16141319

  10. Extending cassava root shelf life via reduction of reactive oxygen species production.

    PubMed

    Zidenga, Tawanda; Leyva-Guerrero, Elisa; Moon, Hangsik; Siritunga, Dimuth; Sayre, Richard

    2012-08-01

    One of the major constraints facing the large-scale production of cassava (Manihot esculenta) roots is the rapid postharvest physiological deterioration (PPD) that occurs within 72 h following harvest. One of the earliest recognized biochemical events during the initiation of PPD is a rapid burst of reactive oxygen species (ROS) accumulation. We have investigated the source of this oxidative burst to identify possible strategies to limit its extent and to extend cassava root shelf life. We provide evidence for a causal link between cyanogenesis and the onset of the oxidative burst that triggers PPD. By measuring ROS accumulation in transgenic low-cyanogen plants with and without cyanide complementation, we show that PPD is cyanide dependent, presumably resulting from a cyanide-dependent inhibition of respiration. To reduce cyanide-dependent ROS production in cassava root mitochondria, we generated transgenic plants expressing a codon-optimized Arabidopsis (Arabidopsis thaliana) mitochondrial alternative oxidase gene (AOX1A). Unlike cytochrome c oxidase, AOX is cyanide insensitive. Transgenic plants overexpressing AOX exhibited over a 10-fold reduction in ROS accumulation compared with wild-type plants. The reduction in ROS accumulation was associated with a delayed onset of PPD by 14 to 21 d after harvest of greenhouse-grown plants. The delay in PPD in transgenic plants was also observed under field conditions, but with a root biomass yield loss in the highest AOX-expressing lines. These data reveal a mechanism for PPD in cassava based on cyanide-induced oxidative stress as well as PPD control strategies involving inhibition of ROS production or its sequestration. PMID:22711743

  11. Response of phytoplankton and dissolved oxygen and related marine ecological parameters to typhoon tropical cyclone in the oceans

    NASA Astrophysics Data System (ADS)

    Tang, DanLing

    Typhoons (tropical cyclones, or hurricanes) are strong wind events in the weather system, which influence the upper ocean dynamics and the ecosystem, in particular upwelling, water temperature, salinity, chlorophyll-a (Chl-a) concentration and primary production and fish abundances. But little is known about the response of dissolved oxygen (DO) concentration to a typhoon in the open ocean. This paper investigates the impact of a typhoon on DO concentration and related ecological parameters using in-situ and remote sensing data. The in-situ data were collected one week after the passage of the super-typhoon Nanmadol in the northern South China Sea in 2011. An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track. At these stations, maximum DO concentration was found at a depth of around 5 m and maximum Chl-a concentration at depths between 50 m and 75 m. The layer of high DO concentration extends from the surface to a depth of 35 m and the concentrations stay almost constant down to this depth. Due to the passage of the typhoon, also a large sea level anomaly (21.6 cm) and a high value of Ekman pumping velocity (4.0×10-4 m s-1) are observed, indicating upwelling phenomenon. At the same time, also intrusion of Kuroshio waters in the form of a loop current into the South China Sea (SCS) was observed. We attribute the increase of DO concentration after the passage of the typhoon to three effects:1) entrainment of oxygen from the air into the upper water layer and strong vertical mixing of the water body due to the typhoon winds, 2) upwelling of cold nutrient-rich water which stimulates photosynthesis of phytoplankton and thus the generation of oxygen, which also increases the DO concentration due to cold water since the solubility of oxygen increase with decreasing water temperature, and, possibly, 3) transport of DO enriched waters

  12. Quantifying seascape structure: Extending terrestrial spatial pattern metrics to the marine realm

    USGS Publications Warehouse

    Wedding, L.M.; Christopher, L.A.; Pittman, S.J.; Friedlander, A.M.; Jorgensen, S.

    2011-01-01

    Spatial pattern metrics have routinely been applied to characterize and quantify structural features of terrestrial landscapes and have demonstrated great utility in landscape ecology and conservation planning. The important role of spatial structure in ecology and management is now commonly recognized, and recent advances in marine remote sensing technology have facilitated the application of spatial pattern metrics to the marine environment. However, it is not yet clear whether concepts, metrics, and statistical techniques developed for terrestrial ecosystems are relevant for marine species and seascapes. To address this gap in our knowledge, we reviewed, synthesized, and evaluated the utility and application of spatial pattern metrics in the marine science literature over the past 30 yr (1980 to 2010). In total, 23 studies characterized seascape structure, of which 17 quantified spatial patterns using a 2-dimensional patch-mosaic model and 5 used a continuously varying 3-dimensional surface model. Most seascape studies followed terrestrial-based studies in their search for ecological patterns and applied or modified existing metrics. Only 1 truly unique metric was found (hydrodynamic aperture applied to Pacific atolls). While there are still relatively few studies using spatial pattern metrics in the marine environment, they have suffered from similar misuse as reported for terrestrial studies, such as the lack of a priori considerations or the problem of collinearity between metrics. Spatial pattern metrics offer great potential for ecological research and environmental management in marine systems, and future studies should focus on (1) the dynamic boundary between the land and sea; (2) quantifying 3-dimensional spatial patterns; and (3) assessing and monitoring seascape change. ?? Inter-Research 2011.

  13. Oxygen isotopes of marine mollusc shells record Eocene elevation change in the Pyrenees

    NASA Astrophysics Data System (ADS)

    Huyghe, Damien; Mouthereau, Frédéric; Emmanuel, Laurent

    2012-09-01

    Constraining paleoaltimetry of collisional orogens is critical to understand the dynamics of topographic evolution and climate/tectonics retroactions. Here, we use oxygen stable-isotope record on oyster shells, preserved in marine foreland deposits, to examine the past elevation of the Pyrenees during the Eocene. Our approach is based on the comparison with the Paris basin, an intracratonic basin not influenced by orogenic growth. The finding of a shift of 1.5‰ between 49 and 41 Ma, indicating more negative δ18Oc in the south Pyrenean foreland, is interpreted to reflect the inflow of river water sourced from higher elevation in the Pyrenees. To test this and provide paleoelevation estimate, we adopt a morphologic-hydrological model accounting for the hypsometry of drainage basin. Our best fitting model shows that the Pyrenees rose up to 2000 m. This indicates that the Pyrenees reached high elevation in the Eocene, thus providing new critical constraints on their long-term orogenic development. δ18O of marine mollusc shells are proved potentially attractive for paleoelevation studies, especially for mountain belts where elevated continental surfaces have not been preserved.

  14. Oxygen Delivery from Hyperbarically Loaded Microtanks Extends Cell Viability in Anoxic Environments

    PubMed Central

    Cook, Colin A.; Hahn, Kathryn C.; Morrissette-McAlmon, Justin B.F.; Grayson, Warren L.

    2016-01-01

    Oxygen diffusion limitations within nascent tissue engineered (TE) grafts lead to the development of hypoxic regions, cell death, and graft failure. Previous efforts have been made to deliver oxygen within TE scaffolds, including peroxide-doping, perfluorocarbons, and hyperbaric oxygen therapy, to mitigate these effects and help maintain post transplantation cell viability, but these have suffered from significant drawbacks. Here we present a novel approach utilizing polymeric hollow-core microspheres that can be hyperbarically loaded with oxygen and subsequently provide prolonged oxygen delivery. These oxygen carriers are termed, microtanks. With an interest in orthopedic applications, we combined microtanks within polycaprolactone to form solid phase constructs with oxygen delivery capabilities. The mathematical laws governing oxygen delivery from microtank-loaded constructs are developed along with empirical validation. Constructs achieved periods of oxygen delivery out to 6 days, which was shown to prolong the survival of human adipose derived stem cells (hASCs) and human umbilical vein endothelial cells (HUVECs) as well as to enhance their cellular morphology under anoxic conditions. The results of this study suggest the microtank approach may be a feasible means of maintaining cell viability in TE scaffolds during the critical period of vascularization in vivo. PMID:25818444

  15. Oxygen delivery from hyperbarically loaded microtanks extends cell viability in anoxic environments.

    PubMed

    Cook, Colin A; Hahn, Kathryn C; Morrissette-McAlmon, Justin B F; Grayson, Warren L

    2015-06-01

    Oxygen diffusion limitations within nascent tissue engineered (TE) grafts lead to the development of hypoxic regions, cell death, and graft failure. Previous efforts have been made to deliver oxygen within TE scaffolds, including peroxide-doping, perfluorocarbons, and hyperbaric oxygen therapy, to mitigate these effects and help maintain post transplantation cell viability, but these have suffered from significant drawbacks. Here we present a novel approach utilizing polymeric hollow-core microspheres that can be hyperbarically loaded with oxygen and subsequently provide prolonged oxygen delivery. These oxygen carriers are termed, microtanks. With an interest in orthopedic applications, we combined microtanks within polycaprolactone to form solid phase constructs with oxygen delivery capabilities. The mathematical laws governing oxygen delivery from microtank-loaded constructs are developed along with empirical validation. Constructs achieved periods of oxygen delivery out to 6 days, which was shown to prolong the survival of human adipose derived stem cells (hASCs) and human umbilical vein endothelial cells (HUVECs) as well as to enhance their cellular morphology under anoxic conditions. The results of this study suggest the microtank approach may be a feasible means of maintaining cell viability in TE scaffolds during the critical period of vascularization in vivo. PMID:25818444

  16. Equilibrium oxygen isotope behavior of sulfate in marine sediments: A new paradigm

    NASA Astrophysics Data System (ADS)

    Blake, R.; Boettcher, M.; Surkov, A.; Ferdelman, T.; Jorgensen, B.

    2006-05-01

    We have determined the oxygen (18O/16O) and sulfur (34S/32S) isotope ratios of porewater sulfate to depths of over 400 mbsf in sediments from open-ocean and upwelling sites in the Eastern Equatorial Pacific ocean. Sulfate δ18O ranges from near-normal seawater values (9.5 permil) at organic-poor open-ocean sites, to approximately 30 permil at sites with higher organic matter content and higher associated microbial activity. Depth-correlative trends of δ18O, δ34S, alkalinity, methane, ammonium and the presence of sulfide, indicate significant oxidation of sedimentary organic matter by sulfate-reducing microbial populations as well as anaerobic oxidation of methane. δ18O ?SO4 values at low-activity sites reveal the presence of significant microbial sulfur-cycling activity despite relatively flat sulfate concentration and δ34S profiles. This activity may include contributions from several processes including: enzyme-catalyzed equilibration between oxygen in sulfate and water superimposed upon microbial sulfate reduction, sulfide oxidation, and bacterial disproportionation of sulfur intermediates. Positive correlation between water and sulfate δ18O values supports sulfate-water O isotope exchange as the dominant process controlling porewater sulfate δ18O values. Results of this study indicate that coupled measurements of S and O isotope ratios of porewater sulfate are essential for interpreting microbial sulfur cycling in marine sediments.

  17. Iron Complexation to Oxygen Rich Marine Natural Products: A Computational Study

    PubMed Central

    Manning, Thomas J.; Williams, Jimmy; Jarrard, Joey; Gorman, Teresa

    2010-01-01

    The natural products kahalalide F, halichondrin B, and discodermolide are relatively large structures that were originally harvested from marine organisms. They are oxygen rich structures that, to varying degrees, should have the ability to bind iron (II or III) by Fe-O and/or Fe-N bonds. In this semi empirical study, the binding of these natural products to iron (II) is studied and the aqueous stability factor (ASF) is used to determine which bonding configuration is most stable. The energy, the complex charge (+1), the average Fe-O (or Fe-N) bond distances and the dipole moments are used to calculate the ASF. The ASF provides insight to which complex will be the most stable and water soluble, important for a medicinal application. The ability of a molecule with a more than six oxygen and/or nitrogen atoms to bind iron (hexavalent, octahedral) by shifting which six atoms (O/N) are bound to the iron qualifies it as a polarity adaptive molecule. PMID:20161968

  18. The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation

    USGS Publications Warehouse

    Claypool, George E.; Holser, William T.; Kaplan, Isaac R.; Sakai, Hitoshi; Zak, Israel

    1980-01-01

    Three hundred new samples of marine evaporite sulfate, of world-wide distribution, were analyzed for δ34S, and 60 of these also for δ18O in the sulfate ion. Detailed δ34S age curves for Tertiary—Cretaceous, Permian—Pennsylvanian, Devonian, Cambrian and Proterozoic times document large variations in δ34S. A summary curve forδ18O also shows definite variations, some at different times than δ34S, and always smaller. The measured δ34S and δ18O correspond to variations in these isotopes in sulfate of the world ocean surface. The variations of δ18O are controlled by input and output fluxes of sulfur in the ocean, three of which are the same that control δ34S: deposition and erosion of sulfate, and deposition of sulfide. Erosion of sulfide differs in its effect on the S and O systems. δ18O in the sulfate does not seem to be measurably affected by equilibration with either seawater or with subsurface waters after crystallization. In principle, the simultaneous application of both δ34S and δ18O age curves should help reduce the number of assumptions in calculations of the cycles of sulfur and oxygen through geological time, and a new model involving symmetrical fluxes is introduced here to take advantage of the oxygen data. However, all previously published models as well as this one lead to anomalies, such as unreasonable calcium or oxygen depletions in the ocean—atmosphere system. In addition, most models are incapable of reproducing the sharp rises of the δ34S curve in the late Proterozoic, the Devonian and the Triassic which would be the result of unreasonably fast net sulfide deposition. This fast depletion could result from an ocean that has not always been mixed (as previously assumed in all model calculations).

  19. Prevalence and diversity of extended-spectrum-β-lactamase-producing Enterobacteriaceae from marine beach waters.

    PubMed

    Maravić, Ana; Skočibušić, Mirjana; Cvjetan, Svjetlana; Šamanić, Ivica; Fredotović, Željana; Puizina, Jasna

    2015-01-15

    A total of 1,351 Enterobacteriaceae isolates from 144 seawater samples were collected over a four-year period from three public beaches in the eastern Adriatic Sea in Croatia. Approximately 35% of the strains were multidrug-resistant. BlaESBL genes were detected in 4.2% of the isolated Enterobacteriaceae, the main species of which were Escherichia coli, Enterobacter cloacae and Klebsiella pneumoniae. BlaTEM-1+SHV-12 was the most dominant genotype, followed by blaCTX-M-15.Raoultella terrigena and E. intermedius simultaneously harboured blaTEM-1,blaSHV-11/12 and blaCTX-M-15. Isolate fingerprinting revealed that marine E. coli isolates were clonally related to CTX-M-producing strains from a regional university hospital. These results indicate that marine beach waters are reservoirs of ESBL-producing Enterobacteriaceae and thus constitute a public health problem with further potential to act as mediators in gene flow between marine coastal areas and clinical settings. PMID:25480155

  20. Experimental investigation of engine emissions with marine gas oil-oxygenate blends.

    PubMed

    Nabi, Md Nurun; Hustad, Johan Einar

    2010-07-15

    This paper investigates the diesel engine performance and exhaust emissions with marine gas oil-alternative fuel additive. Marine gas oil (MGO) was selected as base fuel for the engine experiments. An oxygenate, diethylene glycol dimethyl ether (DGM), and a biodiesel (BD) jatropha oil methyl ester (JOME) with a volume of 10% were blended with the MGO fuel. JOME was derived from inedible jatropha oil. Lower emissions with diesel-BD blends (soybean methyl ester, rapeseed methyl ester etc.) have been established so far, but the effect of MGO-BD (JOME) blends on engine performance and emissions has been a growing interest as JOME (BD) is derived from inedible oil and MGO is frequently used in maritime transports. No phase separation between MGO-DGM and MGO-JOME blends was found. The neat MGO, MGO-DGM and MGO-JOME blends are termed as MGO, Ox10 and B10 respectively. The experiments were conducted with a six-cylinder, four-stroke, turbocharged, direct-injection Scania DC 1102 (DI) diesel engine. The experimental results showed significant reductions in fine particle number and mass emissions, PM and smoke emissions with Ox10 and B10 fuels compared to the MGO fuel. Other emissions including total unburned hydrocarbon (THC), carbon monoxide (CO) and engine noise were also reduced with the Ox10 and B10 fuels, while maintaining similar brake specific fuel consumption (BSFC) and thermal efficiency with MGO fuel. Oxides of nitrogen (NOx) emissions, on the other hand, were slightly higher with the Ox10 and B10 fuels at high engine load conditions. PMID:20452651

  1. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone

    PubMed Central

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2014-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2–1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2–1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms. PMID:24030599

  2. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone.

    PubMed

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2014-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2-1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2-1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms. PMID:24030599

  3. Protist communities in a marine oxygen minimum zone off Costa Rica by 454 pyrosequencing

    NASA Astrophysics Data System (ADS)

    Jing, H.; Rocke, E.; Kong, L.; Xia, X.; Liu, H.; Landry, M. R.

    2015-08-01

    Marine planktonic protists, including microalgae and protistan grazers, are an important contributor to global primary production and carbon and mineral cycles, however, little is known about their population shifts along the oxic-anoxic gradient in the water column. We used 454 pyrosequencing of the 18S rRNA gene and gene transcripts to study the community composition of whole and active protists throughout a water column in the Costa Rica Dome, where a stable oxygen minimum zone (OMZ) exists at a depth of 400~700 m. A clear shift of protist composition from photosynthetic Dinoflagellates in the surface to potential parasitic Dinoflagellates and Ciliates in the deeper water was revealed along the vertical profile at both rRNA and rDNA levels. Those protist groups recovered only at the rDNA level represent either lysed aggregates sinking from the upper waters or potential hosts for parasitic groups. UPGMA clustering demonstrated that total and active protists in the anoxic core of OMZ (550 m) were distinct from those in other water depths. The reduced community diversity and presence of a parasitic/symbiotic trophic lifestyle in the OMZ, especially the anoxic core, suggests that OMZs can exert a selective pressure on protist communities. Such changes in community structure and a shift in trophic lifestyle could result in a modulation of the microbial loop and associated biogeochemical cycling.

  4. Timing and extent of early marine oxygen isotope stage 2 alpine glaciation in Skagit Valley, Washington

    NASA Astrophysics Data System (ADS)

    Riedel, Jon L.; Clague, John J.; Ward, Brent C.

    2010-03-01

    Twenty-two new radiocarbon ages from Skagit valley provide a detailed chronology of alpine glaciation during the Evans Creek stade of the Fraser Glaciation (early marine oxygen isotope stage (MIS) 2) in the Cascade Range, Washington State. Sediments at sites near Concrete, Washington, record two advances of the Baker valley glacier between ca. 30.3 and 19.5 cal ka BP, with an intervening period of glacier recession about 24.9 cal ka BP. The Baker valley glacier dammed lower Skagit valley, creating glacial Lake Concrete, which discharged around the ice dam along Finney Creek, or south into the Sauk valley. Sediments along the shores of Ross Lake in upper Skagit valley accumulated in glacial Lake Skymo after ca. 28.7 cal ka BP behind a glacier flowing out of Big Beaver valley. Horizontally laminated silt and bedded sand and gravel up to 20 m thick record as much as 8000 yr of deposition in these glacially dammed lakes. The data indicate that alpine glaciers in Skagit valley were far less extensive than previously thought. Alpine glaciers remained in advanced positions for much of the Evans Creek stade, which may have ended as early as 20.8 cal ka BP.

  5. Extended Fine Structure Studies of Surface Reactions of Oxygen and Potassium on ALUMINUM(111)

    NASA Astrophysics Data System (ADS)

    Kim, Eungsoo

    1992-01-01

    The photoemission EXAFS (PEXAFS) technique was applied to determine the surface structures of Al(111) resulting from oxidation, potassium adsorption, and coadsorption of oxygen and potassium. Various elastic photopeaks, and the bulk and surface plasmon loss peaks were used. This technique has proved to be a powerful tool for the surface study because of its chemical sensitivity and surface sensitivity. In clean Al(111) the first and second nearest distances of Al-Al we obtained using the Al 2p elastic photopeak and plasmon loss peaks agree with the bulk values and, hence, no evidence of surface relaxation is found within experimental uncertainty. In the initial oxidation of Al(111), at the exposure of 50L oxygen, the 1.4 eV characteristic chemical shift of the chemisorbed phase was observed. Using the unshifted Al 2p and O 2s photopeaks, the Al-O, Al-Al, and O-O interatomic distances were determined. These results suggest that the oxygen atoms exist in the three-fold hollow sites above the Al surface. This is the first EXAFS measurement using the O 2s edge. With 1000L exposure of oxygen the photoemission study showed a 2.7 eV chemical shift due to an oxide-like phase. By using the unshifted and shifted Al 2p photopeaks, the Al-O and Al-Al distances were determined. These results indicate that the oxygen atoms are located at the octahedral sites below the surface, that is, the alpha -Al_2O_3 (corundum)-like phase is formed. For the potassium adsorption study, 0.2 monolayer (ML) and 1 ML of K were deposited at room temperature. The LEED pattern of the 1 ML K deposit shows a (surd 3 x surd3)R30^ circ structure. Using the Al 2p and K 3p photopeaks, the Al-Al, Al-K, and K-K distances were determined. These results suggest that the K is not highly ionic and tends toward metallic as the coverage increases. Furthermore we find cluster formation of potassium atoms at low coverage, and the observed LEED pattern agrees well with the PEXAFS results. With 10L of oxygen exposure

  6. Phosphate oxygen isotope ratio proxy for specific microbial activity in marine sediments (Peru Margin)

    NASA Astrophysics Data System (ADS)

    Liang, Y.; Blake, R. E.

    2005-12-01

    Oxygen (O) isotope ratios of biogenic apatites have been widely used as paleotemperature and environmental geochemical proxies. With improved knowledge of the phosphate O isotope effects of different P cycling pathways, the δ18O value of inorganic phosphate (δ18OP) has been proposed as a useful proxy and tracer of biological reactions and P cycling in natural environments[1,2,3,4]. Being the only way of removing P from oceanic water, sedimentary P burial is one of the most important processes during biogeochemical cycling of P. The high concentrations of organic matter and pronounced microbial activity at ODP Site 1230 along the Peru Margin result in unusually high interstitial water phosphate concentrations, which provides a unique opportunity to use δ18OP to investigate inorganic phosphate (Pi) regeneration and P cycling pathways in marine sediments. The isotopic measurements of both dissolved inorganic phosphate (DIP) and bulk sediment Pi show that DIP δ18OP values are affected by three different processes, which are all induced by specific microbial activities present in the sediments. In sediments at ~ 65 to 120 mbsf, porewater DIP is derived from dissolved organophosphorus compounds (DOP) through enzymatic degradation pathways, evidenced by both DIP δ18OP values and interstitial water chemistry. Measured porewater DIP δ18OP values also suggest that 4 to 8% of interstitial water DIP reflects regeneration of Pi from Porg by microbially-synthesized enzymes. Throughout the sediment column and especially at ~ 120 to 150 mbsf, DIP is released from the sediments by microbially-induced reductive dissolution of Fe-oxides, which contributes to the overall high DIP concentrations at Site 1230. The third and dominant process controlling measured DIP δ18OP values is microbial turnover of regenerated Pi. The presence of high microbial activities in organic-rich Site 1230 sediments promotes the remobilization of P and affects marine P cycling by potentially enhancing

  7. Cathodic current enhancement via manganese and oxygen related reactions in marine biofilms

    NASA Astrophysics Data System (ADS)

    Strom, Matthew James

    Corrosion is a threat that has economic, and environmental impacts worldwide. Many types of corrosive attack are the subject of ongoing research. One of these areas of research is microbiologically influenced corrosion, which is the enhancement and/or initiation of corrosion events caused by microorganisms. It is well known that colonies of microorganisms can enhance cathodic currents through biofilm formation. The aim of the present work was to elucidate the role of manganese in enhancing cathodic currents in the presence of biofilms. Repeated polarizations conducted in Delaware Bay waters, on biofilm coated Cr identified potentially sustainable reduction reactions. The reduction of MnO2 and the enhancement of the oxygen reduction reaction (ORR) were proven to be factors that influence cathodic current enhancement. The removal of ambient oxygen during polarizations resulted in a shutdown of cathodic current enhancement. These field data led to an exploration of the synergistic relationship between MnO2 and the ORR. Laboratory studies of the catalysis of peroxide disproportionation by MnO2 were monitored using a hanging mercury drop electrode. Experiments were run at an ambient sweater pH of 8 and pH 9, which simulated the near-surface conditions typical of cathodes immersed in seawater. Rapid reoxidation at the more basic pH was shown to allow manganese to behave as a persistent catalyst under the typical electrochemical surface conditions of a cathode. As a result a mechanism for ORR enhancement by manganese was proposed as a unique mechanism for cathodic current enhancement in biofilms. A separate field study of Delaware biofilms on stainless steel coupled to a sacrificial Al anode was carried out to identify the ORR enhancement mechanism and sustainable redox reactions at the cathode. Chemical treatments of glutaraldehyde and formaldoxime were applied to cathodes with biofilms to distinguish between enzymatic and MnO2 related ORR enhancement. The results ruled

  8. Study of oxygen isotopes and N=8 isotones with an extended cluster-orbital shell model

    NASA Astrophysics Data System (ADS)

    Masui, H.; Katō, K.; Ikeda, K.

    2006-03-01

    We attempt to obtain a unified description of the bound and unbound states of multivalence nucleons of a core system in the framework of the cluster-orbital shell model (COSM). In this framework, the interaction between the core and a valence nucleon (the core-N interaction) is treated microscopically, and the changes in both the core structure and the core-N interaction are discussed on the same basis. Furthermore, the center-of-mass motion of every nucleon is completely eliminated, and higher shell configurations, including unbound continuum components, are appropriately taken into account by applying a stochastic variational approach. To examine the reliability of this approach and to discuss how the dynamics of the core reflects to the total system, we study oxygen isotopes and N=8 isotones, which are described by O16 + Xn and O16 + Xp models, respectively.

  9. A manganese sulfite with extended metal-oxygen-metal bonds exhibiting hydrogen uptake

    SciTech Connect

    Rao, K. Prabhakara; Govindaraj, A.; Rao, C.N.R.

    2007-12-15

    A manganese sulfite of the formula Mn{sub 5}(OH){sub 4}(SO{sub 3}){sub 3}.2H{sub 2}O, I{l_brace}a=7.5759(7) A, b=8.4749(8) A, c=10.852(1) A, {beta}=100.732(2){sup o}, Z=2, space group=P2{sub 1}/m (no. 11), R{sub 1}=0.0399 and wR{sub 2}=0.1121 [for R indexes I>2{sigma}(I)]{r_brace}, comprising Mn{sub 3}O{sub 14} units and extended Mn-O-Mn bonds along the three dimensions has been synthesized under hydrothermal conditions. It has narrow channels along the b-axis and exhibits hydrogen storage of 2.1 wt% at 300 K and 134 bar. - Graphical abstract: A three-dimensional manganese sulfite with one-dimensional channels showing selective hydrogen absorption has been synthesized and characterized.

  10. Heterogeneous sources of oxygenated hydrocarbons in the tropical free troposphere: Field evidence for a biogeochemical cycle of marine organic carbon?

    NASA Astrophysics Data System (ADS)

    Volkamer, R.; Apel, E. C.; Baidar, S.; Coburn, S.; Dix, B. K.; Hornbrook, R. S.; Pierce, R.; Ortega, I.; Romashkin, P.; Wang, S.

    2013-12-01

    Oceans cover 70% of the Earth surface, and the amount of dissolved organic carbon (DOC) contained in the world's oceans is comparable to that of atmospheric CO2. Yet oceans are currently believed to be a net-receptor for organic carbon that is emitted over land. Recent our observations of very short-lived and very water soluble oxygenated hydrocarbons, like glyoxal, in the remote marine boundary layer (MBL) above the Pacific Ocean (Sinreich et al., 2010, ACP) remain as of yet unexplained by atmospheric models. Organic carbon is relevant in the atmosphere because it influences the reactive chemical removal pathways of climate active gases (i.e., ozone, methane, dimethyl-sulfide), and can modify aerosols (e.g., secondary organic aerosol, SOA). This presentation provides a comprehensive field evidence that small oxygenated molecules (glyoxal, methyl ethyl ketone, butanal) from marine sources are widespread also in the tropical free troposphere. The data were collected as part of the Tropical Ocean tRoposphere Exchange experiment TORERO during Jan/Feb 2012 by means of an innovative payload of optical spectroscopic-, mass spectrometric-, and remote sensing instruments aboard the NSF/NCAR GV aircraft (HIAPER), and aboard a NOAA ship. We have measured oxygenated hydrocarbons, and volatile organic compounds (some 50+ species), aerosol size distributions, photolysis frequencies and other parameters over the full tropospheric air column (0-15km altitude) between 40N to 40S latitude over the eastern tropical Pacific Ocean. We investigate the source mechanism, present source estimates of the organic carbon flux, and compare it with other sources of organic carbon from marine sources. We also present results from numerical models that suggest a strong impact of these molecules on the oxidative capacity of the tropical free troposphere, where most of tropospheric ozone mass resides, 60-80% of the global methane destruction occurs, and mercury oxidation rates are accelerated at

  11. Reconstructing Holocene bottom water oxygenation and fluvial discharge in the marine environment near Eureka, California using a portable XRF method

    NASA Astrophysics Data System (ADS)

    Burtt, D. G.; Addison, J. A.; Foster, A. L.

    2013-12-01

    X-ray fluorescence (XRF) spectrometry is a method of performing chemical composition analysis of bulk samples. Traditionally, samples are processed gradually over days or weeks to create topographically flat, dry, and homogenous compositions. The current experiment applies this technique for rapid measurement of chemical composition in intact marine sediment cores. We used a handheld Thermo Scientific NitonXL3t-950 XRF to measure the core TN062-O550 (40.867 N, 124.572 W, 550 m water depth), which was collected from 13 km off the coast of Eureka, California. Custom calibrations were developed to accommodate marine sediments, and measurements collected by hand were compared to those taken using a custom-built sediment core stand. Following the initial calibration tests, the portable XRF was used to assess water column oxygen levels within TN062-O550 over the last 4000 years. This assessment was based upon the relatively well-known correspondence between iron and titanium, which can be used to infer the relative abundance of ferric and ferrous minerals, and therefore serve as a proxy for ambient oxygen levels. In addition to testing the oxygenation, these analyses were used to investigate the potential correlation between iron levels and deposition by fluvial discharge and/or surface run-off (rainfall). We found a strongly positive correlation between iron and titanium throughout the length of the core. This correlation suggests that more oxidized iron has accumulated than reduced iron, thus implying oxygenation in the water column and/or upper sediment profile. This is further supported by pervasive bioturbation in the sediment core. These results also have implications for applying these geochemical data as a proxy for regional precipitation and/or fluvial deposition in the marine environment. Based on a preliminary age-depth model developed for TN062-O550, and application of the iron and titanium concentrations as a precipitation proxy, there is a relative maximum

  12. Marine biological production from in situ oxygen measurements on a profiling float in the subarctic Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Bushinsky, Seth M.; Emerson, Steven

    2015-12-01

    Evaluating the organic carbon flux from the surface ocean to the interior (the marine biological pump) is essential for predictions of ocean carbon cycle feedback to climate change. One approach for determining these fluxes is to measure the concentration of oxygen in the upper ocean over a seasonal cycle, calculate the net O2 flux using an upper ocean model, and then use a stoichiometric relationship between oxygen evolved and organic carbon produced. Applying this tracer in a variety of ocean areas over seasonal cycles requires accurate O2 measurements on autonomous vehicles. Here we demonstrate this approach using an O2 sensor on a profiling float that is periodically calibrated against atmospheric pO2. Using accurate data and a model that includes all physical and biological processes influencing oxygen, we determine an annual net community production of 0.7 ± 0.5 mol C m-2 yr-1 in the northeast Pacific Ocean (50°N, 145°W) from June 2012 to June 2013. There is a strong seasonal cycle in net biological oxygen production with wintertime fluxes caused by bubble processes critical to determining the annual flux. Approximately 50% of net autotrophic production during summer months is consumed by net respiration during the winter. The result is a biological pump in the subarctic Pacific Ocean that is less than that determined by similar methods in the subtropics to the south. This estimate is significantly lower than that predicted by satellite remote sensing and global circulation models.

  13. Diel Interactions of Oxygenic Photosynthesis and N2 Fixation (Acetylene Reduction) in a Marine Microbial Mat Community

    PubMed Central

    Bebout, Brad M.; Paerl, Hans W.; Crocker, Kenneth M.; Prufert, Leslie E.

    1987-01-01

    Diel variations in N2 fixation (acetylene reduction), CO2 fixation, and oxygen concentrations were measured, on three separate occasions, in a marine microbial mat located on Shackleford Banks, North Carolina. Nitrogenase activity (NA) was found to be inversely correlated with CO2 fixation and, in two of the three diel periods studied, was higher at night than during the day. Oxygen concentrations within the top 3 mm of the mat ranged from 0 to 400 μM on a diel cycle; anaerobic conditions generally persisted below 4 mm. NA in the mat was profoundly affected by naturally occurring oxygen concentrations. Experimentally elevated oxygen concentrations resulted in a significant depression of NA, whereas the addition of the Photosystem II inhibitor 3(3,4-dichlorophenyl)-1,1-dimethylurea decreased oxygen concentrations within the mat and resulted in a significant short-term enhancement of NA. Mat N2-fixing microorganisms include cyanobacteria and heterotrophic, photoautotrophic, and chemolithotrophic eubacteria. Measured (whole-mat) NA is probably due to a combination of the NA of each of these groups of organisms. The relative contributions of each group to whole-mat NA probably varied during diel and seasonal (successional) cycles. Reduced compounds derived from photosynthetic CO2 fixation appeared to be an important source of energy for NA during the day, whereas heterotrophic or chemolithotrophic utilization of reduced compounds appeared to be an important source of energy for NA at night, under reduced ambient oxygen concentrations. Previous estimates of N2 fixation calculated on the basis of daytime measurements may have seriously underestimated diel and seasonal nitrogen inputs in mat systems. PMID:16347456

  14. Flow enhances photosynthesis in marine benthic autotrophs by increasing the efflux of oxygen from the organism to the water

    PubMed Central

    Mass, Tali; Genin, Amatzia; Shavit, Uri; Grinstein, Mor; Tchernov, Dan

    2010-01-01

    Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism’s photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO2. No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs. PMID:20133799

  15. Oxygenated hydrocarbon observations in the tropical free troposphere: Field evidence for a missing biogeochemical cycle of marine organic carbon?

    NASA Astrophysics Data System (ADS)

    Volkamer, Rainer; Apel, Eric; Coburn, Sean; Dix, Barbara; Ortega, Ivan; Sinreich, Roman; Baidar, Sunil; Pierce, Brad; Wang, Siyuan

    2014-05-01

    The amount of dissolved organic carbon (DOC) contained in the world's oceans is comparable to that of atmospheric CO2. Yet oceans are currently believed to be a net-receptor for organic carbon that is emitted over land. Organic carbon is relevant in the atmosphere because it influences the reactive chemical removal pathways of climate active gases (i.e., ozone, methane, dimethyl-sulfide), and can modify aerosols (e.g., secondary organic aerosol, SOA). Recent our observations of very short-lived and very water soluble oxygenated hydrocarbons, like glyoxal, in the remote marine boundary layer (MBL) above the Pacific Ocean (Sinreich et al., 2010, ACP) remain as of yet unexplained by atmospheric models. Here we present recent measurements of trace-gases over the Eastern tropical and subtropical Pacific Ocean in the Southern Hemisphere, and show that small oxygenated molecules (glyoxal, methyl ethyl ketone, butanal) from marine sources are widespread over the remote oligotrophic ocean, and also in the free troposphere. The data were collected as part of the Tropical Ocean tRoposphere Exchange experiment TORERO during Jan/Feb 2012 by means of an innovative payload of optical spectroscopic-, mass spectrometric-, and remote sensing instruments aboard the NSF/NCAR GV aircraft (HIAPER), and aboard a NOAA ship. We investigate the source mechanism, present source estimates of the organic carbon flux, and compare it with other sources of organic carbon from marine sources. We also present results from numerical models that suggest a strong impact of these molecules on the oxidative capacity of the tropical free troposphere, where most of tropospheric ozone mass resides, 60-80% of the global methane destruction occurs, and mercury oxidation rates are accelerated at low temperatures.

  16. Phosphorus Speciation and Phosphate Oxygen Isotope Systematics of Type Euxinic Marine Deposits from Middle Devonian North America

    NASA Astrophysics Data System (ADS)

    Carney, C. P.; Arthur, M. A.

    2010-12-01

    Perturbation to the P cycle is thought to be an important forcing in episodes of ocean oxygen depletion and enhanced organic C burial, but this relationship remains underconstrained by geochemical data. This geochemical study applies sequential P extraction and subsequent phase-specific PO4-oxygen isotope analyses to the Marcellus Shale Formation - a type euxinic marine unit. Analysis of sedimentary P is assimilated with bulk geochemical data and detailed lithostratigraphy to capture the relationship of P-cycling with evolving sediment inputs, sea level, water column redox conditions, and water column stratification. It is also possible to study the effects of variable thermal history on lithified sediments, as the thermal history of the Marcellus Shale Formation is known throughout the basin. Thermal maturity is compared to variability in P-speciation and PO4-oxygen isotopic composition to control for the effects of secondary diagenesis. A high-resolution oxygen isotope-derived temperature record is important in paleoceanographic reconstruction. In the Middle Devonian, and the Paleozoic in general, diagenetically-robust PO4-oxygen has begun to supplant the CO3-oxygen isotope system in paleothermometry applications due to near pervasive signal overprinting. Conodont elements are the typical source of PO4 for these analyses, but the spatio-temporal distribution of these fossils is limited, and collection from non-carbonate facies is prohibitively labor-intensive. Oxygen isotope analyses of specific fractions of bulk sedimentary phosphate provide a feasible, but relatively unproven alternative. Two recent studies have demonstrated that a large fraction of authigenic P is precipitated in isotopic equilibrium with seawater and that phase partitioning of P can be preserved on hundred-Myr timescales. These results suggest that a PO4 isotope paleoproxy is viable. This study expands the scope of application to paleosediments with high-resolution data and complimentary

  17. Evidence of enzymatic catalysis of oxygen reduction on stainless steels under marine biofilm.

    PubMed

    Faimali, Marco; Benedetti, Alessandro; Pavanello, Giovanni; Chelossi, Elisabetta; Wrubl, Federico; Mollica, Alfonso

    2011-04-01

    Cathodic current trends on stainless steel samples with different surface percentages covered by biofilm and potentiostatically polarized in natural seawater were studied under oxygen concentration changes, temperature increases, and additions of enzymic inhibitors to the solution. The results showed that on each surface fraction covered by biofilm the oxygen reduction kinetics resembled a reaction catalyzed by an immobilised enzyme with high oxygen affinity (apparent Michaelis-Menten dissociation constant close to K(O(2))(M)  ≈ 10 μM) and low activation energy (W ≈ 20 KJ mole(-1)). The proposed enzyme rapidly degraded when the temperature was increased above the ambient (half-life time of ∼1 day at 25°C, and of a few minutes at 50°C). Furthermore, when reversible enzymic inhibitors (eg sodium azide and cyanide) were added, the cathodic current induced by biofilm growth was inhibited. PMID:21526439

  18. The Dynamic Response of Marine Life to Extreme Temperature and Low Oxygen Events Following the End-Permian Mass Extinction.

    NASA Astrophysics Data System (ADS)

    Pietsch, C.; Bottjer, D. J.

    2014-12-01

    The end-Permian mass extinction was the most devastating taxonomic and ecological crisis in the history of life on Earth. The recovery lasted 5 My making it the longest in geologic history, although the cause of the delay is still heavily debated. We find that additional environmental changes during the recovery interval reset the attempts that marine communities made toward ecological complexity, resulting in the overall appearance of a stagnant recovery. The extinction mechanisms during the end-Permian include extreme temperature change and low oxygen environments resulting from the volcanic emission of carbon dioxide and other toxic gasses to the atmosphere. The biotic response to ancient environmental change is a direct analog for the ecological impacts of modern anthropogenic climate change. We applied an ecological recovery rubric to benthic, sea floor dwelling, communities throughout the Early Triassic recovery in two major ocean basins. Newly collected bulk fossil data from the Moenkopi and Thaynes Formations from the Southwest US and the Werfen Formation in Italy were analyzed along with literature data. In Italy, directly following the extinction, low oxygen environments prevented an ecological rebound. Once low oxygen conditions receded, 600 kyr after the extinction, taxonomic diversity, fossil body size, and trace fossil complexity rebounded. A little more than 1 My into the Early Triassic, an extreme temperature event resulted in a reset of community complexity in both Italy and the Southwest US. The body size of gastropods and the repopulation of echinoderms were significantly inhibited as was trace fossil complexity. Low oxygen conditions that developed in the last ~2My of the Early Triassic limited diversity and body size in the Southwest United States. The stagnant recovery is re-interpreted as dynamic resets and rapid rebounds driven by environmental perturbations throughout the Early Triassic.

  19. In situ fluctuations of oxygen and sulphide in marine microbial sediment ecosystems

    NASA Astrophysics Data System (ADS)

    De Wit, Rutger; Jonkers, Henk M.; Van Den Ende, Frank P.; Van Gemerden, Hans

    Laminated microbial ecosystems (microbial mats) on the island of Schiermonnikoog (The Netherlands) were studied with respect to variation in oxygen and sulphide profiles, depth distributions of photopigments and viable number and cell volume of purple sulphur bacteria. Cyanobacteria occurred in the top 2 mm, the dominant species being Microcoleus chthonoplastes. The blooming of purple sulphur bacteria below the cyanobacterial layer was observed in autumn, the dominant species being the immotile Thiocapsa roseopersicina. Cell volume of this species is indicative of its growth rate. In situ measurements showed strong diel fluctuations in oxygen and sulphide profiles. Frequently, cyanobacteria and purple sulphur bacteria were exposed to oxygen during the day, and to anoxic conditions at night. Sulphide sometimes reached the layer of the cyanobacteria. The cyanobacteria and the purple sulphur bacteria both are very well adapted to these diel fluctuations. In addition, strong seasonal variations were observed, whereas short-term fluctuations of oxygen occurred due to changing light-climate and rainfall. Attention was paid to the unusual occurrence of microbial mats on the North Sea beach during the autumn of 1987.

  20. Microbial eukaryote diversity in the marine oxygen minimum zone off northern Chile

    PubMed Central

    Parris, Darren J.; Ganesh, Sangita; Edgcomb, Virginia P.; DeLong, Edward F.; Stewart, Frank J.

    2014-01-01

    Molecular surveys are revealing diverse eukaryotic assemblages in oxygen-limited ocean waters. These communities may play pivotal ecological roles through autotrophy, feeding, and a wide range of symbiotic associations with prokaryotes. We used 18S rRNA gene sequencing to provide the first snapshot of pelagic microeukaryotic community structure in two cellular size fractions (0.2–1.6 μm, >1.6 μm) from seven depths through the anoxic oxygen minimum zone (OMZ) off northern Chile. Sequencing of >154,000 amplicons revealed contrasting patterns of phylogenetic diversity across size fractions and depths. Protist and total eukaryote diversity in the >1.6 μm fraction peaked at the chlorophyll maximum in the upper photic zone before declining by ~50% in the OMZ. In contrast, diversity in the 0.2–1.6 μm fraction, though also elevated in the upper photic zone, increased four-fold from the lower oxycline to a maximum at the anoxic OMZ core. Dinoflagellates of the Dinophyceae and endosymbiotic Syndiniales clades dominated the protist assemblage at all depths (~40–70% of sequences). Other protist groups varied with depth, with the anoxic zone community of the larger size fraction enriched in euglenozoan flagellates and acantharean radiolarians (up to 18 and 40% of all sequences, respectively). The OMZ 0.2–1.6 μm fraction was dominated (11–99%) by Syndiniales, which exhibited depth-specific variation in composition and total richness despite uniform oxygen conditions. Metazoan sequences, though confined primarily to the 1.6 μm fraction above the OMZ, were also detected within the anoxic zone where groups such as copepods increased in abundance relative to the oxycline and upper OMZ. These data, compared to those from other low-oxygen sites, reveal variation in OMZ microeukaryote composition, helping to identify clades with potential adaptations to oxygen-depletion. PMID:25389417

  1. Sulfur record of rising and falling marine oxygen and sulfate levels during the Lomagundi event.

    PubMed

    Planavsky, Noah J; Bekker, Andrey; Hofmann, Axel; Owens, Jeremy D; Lyons, Timothy W

    2012-11-01

    Carbonates from approximately 2.3-2.1 billion years ago show markedly positive δ(13)C values commonly reaching and sometimes exceeding +10‰. Traditional interpretation of these positive δ(13)C values favors greatly enhanced organic carbon burial on a global scale, although other researchers have invoked widespread methanogenesis within the sediments. To resolve between these competing models and, more generally, among the mechanisms behind Earth's most dramatic carbon isotope event, we obtained coupled stable isotope data for carbonate carbon and carbonate-associated sulfate (CAS). CAS from the Lomagundi interval shows a narrow range of δ(34)S values and concentrations much like those of Phanerozoic and modern marine carbonate rocks. The δ(34)S values are a close match to those of coeval sulfate evaporites and likely reflect seawater composition. These observations are inconsistent with the idea of diagenetic carbonate formation in the methanic zone. Toward the end of the carbon isotope excursion there is an increase in the δ(34)S values of CAS. We propose that these trends in C and S isotope values track the isotopic evolution of seawater sulfate and reflect an increase in pyrite burial and a crash in the marine sulfate reservoir during ocean deoxygenation in the waning stages of the positive carbon isotope excursion. PMID:23090989

  2. Sulfur record of rising and falling marine oxygen and sulfate levels during the Lomagundi event

    PubMed Central

    Planavsky, Noah J.; Bekker, Andrey; Hofmann, Axel; Owens, Jeremy D.; Lyons, Timothy W.

    2012-01-01

    Carbonates from approximately 2.3–2.1 billion years ago show markedly positive δ13C values commonly reaching and sometimes exceeding +10‰. Traditional interpretation of these positive δ13C values favors greatly enhanced organic carbon burial on a global scale, although other researchers have invoked widespread methanogenesis within the sediments. To resolve between these competing models and, more generally, among the mechanisms behind Earth’s most dramatic carbon isotope event, we obtained coupled stable isotope data for carbonate carbon and carbonate-associated sulfate (CAS). CAS from the Lomagundi interval shows a narrow range of δ34S values and concentrations much like those of Phanerozoic and modern marine carbonate rocks. The δ34S values are a close match to those of coeval sulfate evaporites and likely reflect seawater composition. These observations are inconsistent with the idea of diagenetic carbonate formation in the methanic zone. Toward the end of the carbon isotope excursion there is an increase in the δ34S values of CAS. We propose that these trends in C and S isotope values track the isotopic evolution of seawater sulfate and reflect an increase in pyrite burial and a crash in the marine sulfate reservoir during ocean deoxygenation in the waning stages of the positive carbon isotope excursion. PMID:23090989

  3. Eleganketal A, a highly oxygenated dibenzospiroketal from the marine-derived fungus Spicaria elegans KLA03.

    PubMed

    Luan, Yepeng; Wei, Hongjuan; Zhang, Zhenpei; Che, Qian; Liu, Yankai; Zhu, Tianjiao; Mándi, Attila; Kurtán, Tibor; Gu, Qianqun; Li, Dehai

    2014-07-25

    Eleganketal A (1), a naturally occurring aromatic polyketide possessing a rare highly oxygenated spiro[isobenzofuran-1,3'-isochroman] ring system, was isolated from the fungus Spicaria elegans KLA03 by culturing it in a modified mannitol-based medium. The structure of 1 including the absolute configuration was determined by combining spectroscopic analysis, synthesis of the racemic permethylated analogue, chiral-phase HPLC separation, and TDDFT-ECD analysis. PMID:24967847

  4. Scavenging capacity of marine carotenoids against reactive oxygen and nitrogen species in a membrane-mimicking system.

    PubMed

    Rodrigues, Eliseu; Mariutti, Lilian R B; Mercadante, Adriana Z

    2012-08-01

    Carotenoid intake has been associated with the decrease of the incidence of some chronic diseases by minimizing the in vivo oxidative damages induced by reactive oxygen (ROS) and nitrogen species (RNS). The carotenoids are well-known singlet oxygen quenchers; however, their capacity to scavenge other reactive species, such as peroxyl radical (ROO•, hydroxyl radical (HO•), hypochlorous acid (HOCl) and anion peroxynitrite (ONOO⁻), still needs to be more extensively studied, especially using membrane-mimicking systems, such as liposomes. Moreover, the identification of carotenoids possessing high antioxidant capacity can lead to new alternatives of drugs or nutritional supplements for prophylaxis or therapy of pathological conditions related to oxidative damages, such as cardiovascular diseases. The capacity to scavenge ROO•, HO•, HOCl and ONOO⁻ of seven carotenoids found in marine organisms was determined in liposomes based on the fluorescence loss of a fluorescent lipid (C₁₁-BODIPY⁵⁸¹/⁵⁹¹) due to its oxidation by these reactive species. The carotenoid-bearing hydroxyl groups were generally more potent ROS scavengers than the carotenes, whilst β-carotene was the most efficient ONOO⁻ scavenger. The role of astaxanthin as an antioxidant should be highlighted, since it was a more potent scavenger of ROO•, HOCl and ONOO⁻ than α-tocopherol. PMID:23015774

  5. Biogeochemical cycling in an organic-rich coastal marine basin. 7. Sulfur mass balance, oxygen uptake and sulfide retention

    USGS Publications Warehouse

    Chanton, J.P.; Martens, C.S.; Goldhaber, M.B.

    1987-01-01

    Sulfur and oxygen fluxes were quantified in the seasonally varying anoxic marine sedimentary system of Cape Lookout Bight, N.C., U.S.A. Over the three year study period, 1981-1983, the mean annual sulfate reduction rate was determined to be 18.2 ?? 1.6 moles ?? m-2 ?? y-1. This value, added to the estimate of the detrital sulfur input of 1.2 ?? 4.4 gave a total sulfur input of 19.4 ?? 4.7 moles ?? m-2 ?? y-1. The sulfide flux to the sediment-water interface, measured in anaerobic benthic chambers was 4.6 ?? 0.5 moles ?? m-2 ?? y-1, and represented 37% of the annual oxygen uptake rate of 25.2 ?? 2.8 moles ?? m-2 ?? y-1. The sulfide burial rate, determined to be 15.5 ?? 3.1 moles ?? m-2 ?? y-1, was within 5% of the value predicted by summing the fluxes at the sediment-water interface. The C S weight ratio of sediment below the depth of diagenetic reaction was determined to be 2.75. The sulfide retention rate in these rapidly accumulating sediments (10 cm/yr) was 77 ?? 19%. Comparison of this result with previous studies shows that rapid sediment accumulation and the lack of bioturbation control this unusually high degree of sulfide retention. ?? 1987.

  6. Verification and application of the extended spectral deconvolution algorithm (SDA+) methodology to estimate aerosol fine and coarse mode extinction coefficients in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Kaku, K. C.; Reid, J. S.; O'Neill, N. T.; Quinn, P. K.; Coffman, D. J.; Eck, T. F.

    2014-10-01

    The spectral deconvolution algorithm (SDA) and SDA+ (extended SDA) methodologies can be employed to separate the fine and coarse mode extinction coefficients from measured total aerosol extinction coefficients, but their common use is currently limited to AERONET (AErosol RObotic NETwork) aerosol optical depth (AOD). Here we provide the verification of the SDA+ methodology on a non-AERONET aerosol product, by applying it to fine and coarse mode nephelometer and particle soot absorption photometer (PSAP) data sets collected in the marine boundary layer. Using data sets collected on research vessels by NOAA-PMEL(National Oceanic and Atmospheric Administration - Pacific Marine Environmental Laboratory), we demonstrate that with accurate input, SDA+ is able to predict the fine and coarse mode scattering and extinction coefficient partition in global data sets representing a range of aerosol regimes. However, in low-extinction regimes commonly found in the clean marine boundary layer, SDA+ output accuracy is sensitive to instrumental calibration errors. This work was extended to the calculation of coarse and fine mode scattering coefficients with similar success. This effort not only verifies the application of the SDA+ method to in situ data, but by inference verifies the method as a whole for a host of applications, including AERONET. Study results open the door to much more extensive use of nephelometers and PSAPs, with the ability to calculate fine and coarse mode scattering and extinction coefficients in field campaigns that do not have the resources to explicitly measure these values.

  7. Dissolved Oxygen Sensor in Animal-Borne Instruments: An Innovation for Monitoring the Health of Oceans and Investigating the Functioning of Marine Ecosystems

    PubMed Central

    Bailleul, Frederic; Vacquie-Garcia, Jade; Guinet, Christophe

    2015-01-01

    The current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. However the impact of its declining on marine life and ecosystems’ health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the Southern Ocean (SO). Southern elephant seals (Mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physical and biogeochemical structure of oceanic regions rarely observed. In this study, we use a new stage of development in biologging technology to draw a picture of dissolved oxygen concentration in the SO. We present the first results obtained from a dissolved oxygen sensor added to Argos CTD-SRDL tags and deployed on 5 female elephant seals at Kerguelen. From October 2010 and October 2011, 742 oxygen profiles associated with temperature and salinity measurements were recorded. Whether a part of the data must be considered cautiously, especially because of offsets and temporal drifts of the sensors, the range of values recorded was consistent with a concomitant survey conducted from a research vessel (Keops-2 project). Once again, elephant seals reinforced the relationship between marine ecology and oceanography, delivering essential information about the water masses properties and the biological status of the Southern Ocean. But more than the presentation of a new stage of development in animal-borne instrumentation, this pilot study opens a new field of investigation in marine ecology and could be enlarged in a near future to other key marine predators, especially large fish species like swordfish, tuna or sharks, for which dissolved oxygen is expected to play a crucial role in distribution and behaviour. PMID:26200780

  8. Dissolved Oxygen Sensor in Animal-Borne Instruments: An Innovation for Monitoring the Health of Oceans and Investigating the Functioning of Marine Ecosystems.

    PubMed

    Bailleul, Frederic; Vacquie-Garcia, Jade; Guinet, Christophe

    2015-01-01

    The current decline in dissolved oxygen concentration within the oceans is a sensitive indicator of the effect of climate change on marine environment. However the impact of its declining on marine life and ecosystems' health is still quite unclear because of the difficulty in obtaining in situ data, especially in remote areas, like the Southern Ocean (SO). Southern elephant seals (Mirounga leonina) proved to be a relevant alternative to the traditional oceanographic platforms to measure physical and biogeochemical structure of oceanic regions rarely observed. In this study, we use a new stage of development in biologging technology to draw a picture of dissolved oxygen concentration in the SO. We present the first results obtained from a dissolved oxygen sensor added to Argos CTD-SRDL tags and deployed on 5 female elephant seals at Kerguelen. From October 2010 and October 2011, 742 oxygen profiles associated with temperature and salinity measurements were recorded. Whether a part of the data must be considered cautiously, especially because of offsets and temporal drifts of the sensors, the range of values recorded was consistent with a concomitant survey conducted from a research vessel (Keops-2 project). Once again, elephant seals reinforced the relationship between marine ecology and oceanography, delivering essential information about the water masses properties and the biological status of the Southern Ocean. But more than the presentation of a new stage of development in animal-borne instrumentation, this pilot study opens a new field of investigation in marine ecology and could be enlarged in a near future to other key marine predators, especially large fish species like swordfish, tuna or sharks, for which dissolved oxygen is expected to play a crucial role in distribution and behaviour. PMID:26200780

  9. Evidence for enhanced phosphorus regeneration from marine sediments overlain by oxygen depleted waters

    SciTech Connect

    Ingall, E.; Jahnki, R.

    1994-06-01

    Phosphorus regeneration and burial fluxes determined from in situ benthic flux chamber and solid phase measurements at sites on the Californian continental margin, Peruvian continental slope, North Carolina continental slope, and from the Santa Monica basin, California are reported. Comparison of these sites indicates that O{sub 2}-depleted bottomwaters enhance P regeneration from sediments, diminishing overall phosphorus burial efficiency. Based on these observations, a positive feedback, linking ocean anoxia, enhanced benthic phosphorus regeneration, and marine productivity is proposed. On shorter timescales, these results also suggest that O{sub 2} depletion in coastal regions caused by eutrophication may enhance P regeneration from sediments, thereby providing additional P necessary for increased biological productivity. 42 refs., 2 figs., 2 tabs.

  10. Putting oxygen and temperature thresholds of marine animals in context of environmental change in coastal seas: a regional perspective for the Scotian Shelf and Gulf of St. Lawrence

    NASA Astrophysics Data System (ADS)

    Brennan, Catherine E.; Blanchard, Hannah; Fennel, Katja

    2014-05-01

    We surveyed the literature in order to compile reported oxygen, temperature, salinity and depth preferences and thresholds of important marine species found in the Gulf of St. Lawrence and the Scotian Shelf regions of the northwest North Atlantic. We determined species importance based on the existence of a commercial fishery, a threatened or at risk status, or by meeting the following criteria: bycatch, baitfish, invasive, vagrant, important for ecosystem energy transfer, and predators and prey of the above species. Using the dataset compiled for the 53 regional fishes and macroinvertebrates, we rank species (including for different lifestages) by their maximum thermal limit, as well as by the lowest oxygen concentration tolerated before negative impacts (e.g. physiological stress), 50% mortality or 100% mortality are experienced. Additionally, we compare these thresholds to observed marine deoxygenation trends at multiple sites, and observed surface warming trends. This results in an assessment of which regional species are most vulnerable to future warming and oxygen depletion, and a first-order estimate of the consequences of thermal and oxygen stress on a highly productive marine shelf. If regional multi-decadal oxygen and temperature trends continue through the 21st century, many species will lose favorable oxygen conditions, experience oxygen-stress, or disappear due to insufficient oxygen. Future warming can additionally displace vulnerable species, though we note that large natural variability in environmental conditions may amplify or dampen the effects of anthropogenic surface warming trends. This dataset may be combined with regional ocean model predictions to map future species distributions.

  11. Extended x-ray absorption fine structure measurements on radio frequency magnetron sputtered HfO2 thin films deposited with different oxygen partial pressures.

    PubMed

    Maidul Haque, S; Nayak, C; Bhattacharyya, Dibyendu; Jha, S N; Sahoo, N K

    2016-03-20

    Two sets of HfO2 thin film have been deposited by the radio frequency magnetron sputtering technique at various oxygen partial pressures, one set without any substrate bias and another set with a 50 W pulsed dc substrate bias. The films have been characterized by extended x-ray absorption fine structure (EXAFS) measurements at the Hf L3 edge, and the structural information obtained from analysis of the EXAFS data has been used to explain the macroscopic behavior of the refractive index obtained from spectroscopic ellipsometry measurements. It has been observed that the variation of refractive index with oxygen partial pressure depends on the Hf-Hf bond length for the set of films deposited without substrate bias, while for the other set of films deposited with pulsed dc substrate bias, it depends on the oxygen coordination of the nearest neighbor shell surrounding Hf sites. PMID:27140550

  12. Induction of apoptosis by three marine algae through generation of reactive oxygen species in human leukemic cell lines.

    PubMed

    Huang, Huey-Lan; Wu, Shwu-Li; Liao, Hui-Fen; Jiang, Chii-Ming; Huang, Ray-Ling; Chen, Yu-Yawn; Yang, Yuh-Cheng; Chen, Yu-Jen

    2005-03-01

    In this study, we examined the antitumor effect of marine algae extracts on human hepatoma and leukemia cells. Ethyl acetate extracts from Colpomenia sinuosa (Cs-EA), Halimeda discoidae (Hd-EA), and Galaxaura oblongata (Go-EA) directly inhibited the growth of human hepatoma HuH-7 cells and leukemia U937 and HL-60 cells in a time- and dose-dependent manner. Specifically, these algae extracts induced apoptosis of U937 and HL-60 cells as evaluated by detection of hypodiploid cells using flow cytometry and observation of condensed and fragmented nuclei in algae extract-treated cells. Intracellular reactive oxygen species (ROS), especially hydrogen peroxide and superoxide anion, were increased about 2-3-fold in U937 cells treated with Cs-EA for 3-5 h. Interestingly, antioxidant N-acetylcysteine effectively blocked Cs-EA-, Hd-EA-, and Go-EA-induced apoptosis, suggesting that ROS is a key mediator in the apoptotic signaling pathway. In conclusion, our results show that algae extracts induce apoptosis in human leukemia cells through generation of ROS. PMID:15740073

  13. Response of dissolved oxygen and related marine ecological parameters to a tropical cyclone in the South China Sea

    NASA Astrophysics Data System (ADS)

    Lin, Jingrou; Tang, Danling; Alpers, Werner; Wang, Sufen

    2014-04-01

    It is well known that tropical cyclones can cause upwelling, decrease of sea surface temperature, increase of chlorophyll-a (Chl-a) concentration and enhancement of primary production. But little is known about the response of dissolved oxygen (DO) concentration to a typhoon in the open ocean. This paper investigates the impact of a typhoon on DO concentration and related ecological parameters using in situ and remote sensing data. The in situ data were collected 1 week after the passage of the super-typhoon Nanmadol in the northern South China Sea in 2011. An increase in DO concentration, accompanied by a decrease in water temperature and an increase in salinity and Chl-a concentration, was measured at sampling stations close to the typhoon track. At these stations, maximum DO concentration was found at a depth of around 5 m and maximum Chl-a concentration at depths between 50 and 75 m. The layer of high DO concentration extends from the surface to a depth of 35 m and the concentrations stay almost constant down to this depth. Due to the passage of the typhoon, also a large sea level anomaly (21.6 cm) and a high value of Ekman pumping velocity (4.0 × 10-4 m s-1) are observed, indicating upwelling phenomenon. At the same time, also intrusion of Kuroshio waters in the form of a loop current into the South China Sea (SCS) was observed. We attribute the increase of DO concentration after the passage of the typhoon to three effects: (1) entrainment of oxygen from the air into the upper water layer and strong vertical mixing of the water body due to the typhoon winds, (2) upwelling of cold nutrient-rich water which stimulates photosynthesis of phytoplankton and thus the generation of oxygen, which also increases the DO concentration due to cold water since the solubility of oxygen increase with decreasing water temperature, and, possibly, (3) transport of DO enriched waters from the Western Pacific to the SCS via the intrusion of Kuroshio waters.

  14. Marine radiocarbon reservoir age variation in Donax obesulus shells from northern Peru: late Holocene evidence for extended El Niño

    USGS Publications Warehouse

    Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Jones, Kevin B.; Hodgins, Gregory W. L.; Sandweiss, Daniel H.; Uceda-Castillo, Sandiago; Quilter, Jeffrey

    2013-01-01

    For at least 6 m.y., El Niño events have posed the greatest environmental risk on the Peruvian coast. A better understanding of El Niño is essential for predicting future risk and growth in this tropical desert. To achieve this we analyzed archaeological and modern pre-bomb shells from the surf clam Donax for the radiocarbon reservoir effect (ΔR) to characterize late Holocene coastal upwelling conditions in northern Peru (8°14′S). Mean ΔR values from these shells suggest that modern upwelling conditions in this region were likely established between A.D. 539 and A.D. 1578. Our radiocarbon data suggest that upwelling conditions ca. A.D. 539 were less intense than those in modern times. The observed coastal water enrichment in 14C may be consequence of frequent strong El Niño events or extended El Niño–like conditions. These ΔR-inferred marine conditions are in agreement with proposed extended El Niño activity in proxy and archaeological records of ca. A.D. 475–530. Extended El Niño conditions have been linked to political destabilization, societal transformation, and collapse of the Moche civilization in northern Peru. A return to such conditions would have significant impacts on the dense population of this region today and in the near future.

  15. Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone.

    PubMed

    Ganesh, Sangita; Bristow, Laura A; Larsen, Morten; Sarode, Neha; Thamdrup, Bo; Stewart, Frank J

    2015-12-01

    The genetic composition of marine microbial communities varies at the microscale between particle-associated (PA; >1.6 μm) and free-living (FL; 0.2-1.6 μm) niches. It remains unclear, however, how metabolic activities differ between PA and FL fractions. We combined rate measurements with metatranscriptomics to quantify PA and FL microbial activity in the oxygen minimum zone (OMZ) of the Eastern Tropical North Pacific, focusing on dissimilatory processes of the nitrogen (N) cycle. Bacterial gene counts were 8- to 15-fold higher in the FL compared with the PA fraction. However, rates of all measured N cycle processes, excluding ammonia oxidation, declined significantly following particle (>1.6 μm) removal. Without particles, rates of nitrate reduction to nitrite (1.5-9.4nMNd(-1)) fell to zero and N2 production by denitrification (0.5-1.7nMNd(-1)) and anammox (0.3-1.9nMNd(-1)) declined by 53-85%. The proportional representation of major microbial taxa and N cycle gene transcripts in metatranscriptomes followed fraction-specific trends. Transcripts encoding nitrate reductase were uniform among PA and FL fractions, whereas anammox-associated transcripts were proportionately enriched up to 15-fold in the FL fraction. In contrast, transcripts encoding enzymes for N2O and N2 production by denitrification were enriched up to 28-fold in PA samples. These patterns suggest that the majority of N cycle activity, excluding N2O and N2 production by denitrification, is confined to a FL majority that is critically dependent on access to particles, likely as a source of organic carbon and inorganic N. Variable particle distributions may drive heterogeneity in N cycle activity and gene expression in OMZs. PMID:25848875

  16. First extended validation of satellite microwave liquid water path with ship-based observations of marine low clouds

    NASA Astrophysics Data System (ADS)

    Painemal, David; Greenwald, Thomas; Cadeddu, Maria; Minnis, Patrick

    2016-06-01

    We present the first extended validation of satellite microwave (MW) liquid water path (LWP) for low nonprecipitating clouds, from four operational sensors, against ship-borne observations from a three-channel MW radiometer collected along ship transects over the northeast Pacific during May-August 2013. Satellite MW retrievals have an overall correlation of 0.84 with ship observations and a bias of 9.3 g/m2. The bias for broken cloud scenes increases linearly with water vapor path and remains below 17.7 g/m2. In contrast, satellite MW LWP is unbiased in overcast scenes with correlations up to 0.91, demonstrating that the retrievals are accurate and reliable under these conditions. Satellite MW retrievals produce a diurnal cycle amplitude consistent with ship-based observations (33 g/m2). Observations taken aboard extended ship cruises to evaluate not only satellite MW LWP but also LWP derived from visible/infrared sensors offer a new way to validate this important property over vast oceanic regions.

  17. The extended phenotypes of marine symbioses: ecological and evolutionary consequences of intraspecific genetic diversity in coral–algal associations

    PubMed Central

    Parkinson, John E.; Baums, Iliana B.

    2014-01-01

    Reef-building corals owe much of their success to a symbiosis with dinoflagellate microalgae in the genus Symbiodinium. In this association, the performance of each organism is tied to that of its partner, and together the partners form a holobiont that can be subject to selection. Climate change affects coral reefs, which are declining globally as a result. Yet the extent to which coral holobionts will be able to acclimate or evolve to handle climate change and other stressors remains unclear. Selection acts on individuals and evidence from terrestrial systems demonstrates that intraspecific genetic diversity plays a significant role in symbiosis ecology and evolution. However, we have a limited understanding of the effects of such diversity in corals. As molecular methods have advanced, so too has our recognition of the taxonomic and functional diversity of holobiont partners. Resolving the major components of the holobiont to the level of the individual will help us assess the importance of intraspecific diversity and partner interactions in coral–algal symbioses. Here, we hypothesize that unique combinations of coral and algal individuals yield functional diversity that affects not only the ecology and evolution of the coral holobiont, but associated communities as well. Our synthesis is derived from reviewing existing evidence and presenting novel data. By incorporating the effects of holobiont extended phenotypes into predictive models, we may refine our understanding of the evolutionary trajectory of corals and reef communities responding to climate change. PMID:25202306

  18. Dynamics of bacterial assemblages and removal of polycyclic aromatic hydrocarbons in oil-contaminated coastal marine sediments subjected to contrasted oxygen regimes.

    PubMed

    Militon, Cécile; Jézéquel, Ronan; Gilbert, Franck; Corsellis, Yannick; Sylvi, Léa; Cravo-Laureau, Cristiana; Duran, Robert; Cuny, Philippe

    2015-10-01

    To study the impact of oxygen regimes on the removal of polycylic aromatic hydrocarbons (PAHs) in oil-spill-affected coastal marine sediments, we used a thin-layer incubation method to ensure that the incubated sediment was fully oxic, anoxic, or was influenced by oxic-anoxic switches without sediment stirring. Hydrocarbon content and microbial assemblages were followed during 60 days to determine PAH degradation kinetics and microbial community dynamics according to the oxygenation regimes. The highest PAH removal, with 69 % reduction, was obtained at the end of the experiment under oxic conditions, whereas weaker removals were obtained under oscillating and anoxic conditions (18 and 12 %, respectively). Bacterial community structure during the experiment was determined using a dual 16S rRNA genes/16S rRNA transcripts approach, allowing the characterization of metabolically active bacteria responsible for the functioning of the bacterial community in the contaminated sediment. The shift of the metabolically active bacterial communities showed that the selection of first responders belonged to Pseudomonas spp. and Labrenzia sp. and included an unidentified Deltaproteobacteria-irrespective of the oxygen regime-followed by the selection of late responders adapted to the oxygen regime. A novel unaffiliated phylotype (B38) was highly active during the last stage of the experiment, at which time, the low-molecular-weight (LMW) PAH biodegradation rates were significant for permanent oxic- and oxygen-oscillating conditions, suggesting that this novel phylotype plays an active role during the restoration phase of the studied ecosystem. PMID:25997808

  19. Re-evaluating origins of Paleozoic orbital-scale and My-scale stratigraphic cyclicity using oxygen isotopes of marine apatite

    NASA Astrophysics Data System (ADS)

    Elrick, M.; Theiling, B. P.; Wallace, Z. A.; Reardon, D.; Labor, W.; Martin, J.

    2012-12-01

    High-frequency (104-105 yr) sedimentary cycles and My-scale depositional sequences in Paleozoic marine strata have been studied for over a century and though debated, their origins are most commonly attributed to sea-level changes. Early studies focused mainly on repetitive shallowing and deepening facies changes, subaerial exposure features, and widespread correlations to argue for eustatic drivers. Subsequent studies utilized 1D and 2D computer models and statistical and time series analysis to argue for eustasy and for Milankovitch-scale periodicities. With increasing high-resolution numeric age control provided by newly discovered ash beds, the durations of many Paleozoic cycles and sequences are found to lie within the Milankovitch-frequency band. Recently the origins of Paleozoic cycles and sequences have been evaluated using oxygen isotopes from marine apatite (conodonts) to specifically test for glacio-eustatic origins. Isotopic trends from well studied Ordovician, Silurian, Devonian, Mississippian, and Pennsylvanian marine successions support the hypothesis that the cycles and sequences were generated by glacio-eustasy with decreasing and low isotopic values occurring within deepening and deepest water facies and increasing and high values occurring in shallowing and shallowest water facies. Of particular interest is that the magnitudes of isotopic change and by inference, the magnitude of climatic change, observed across cycles and sequences developed in Paleozoic greenhouse time intervals (Silurian, Devonian) are as large as those observed in icehouse (Neogene, Pennsylvanian) and transitional (Late Ordovician, Early Mississippian) climatic intervals. These oxygen isotope results combined with earlier stratigraphic, modeling, and statistical studies suggest that short- and long-period Milankovitch-forced glacio-eustasy controlled cycle and sequence development throughout the Paleozoic.

  20. Constraints on Phanerozoic paleotemperature and seawater oxygen isotope evolution from the carbonate clumped isotope compositions of Late Paleozoic marine fossils (Invited)

    NASA Astrophysics Data System (ADS)

    Henkes, G. A.; Passey, B. H.; Grossman, E. L.; Pérez-Huerta, A.; Shenton, B.; Yancey, T. E.

    2013-12-01

    A long-standing geoscience controversy has been the interpretation of the observed several per mil increase in the oxygen isotope compositions of marine calcites over the Phanerozoic Eon. Explanations for this trend have included decreasing seawater paleotemperatures, increasing seawater oxygen isotope values, and post-depositional calcite alteration. Carbonate clumped isotope paleothermometry is a useful geochemical tool to test these hypotheses because of its lack of dependence on the bulk isotopic composition of the water from which carbonate precipitated. This technique is increasingly applied to ancient marine invertebrate shells, which can be screened for diagenesis using chemical and microstructural approaches. After several years of clumped isotope analysis of these marine carbonates in a handful of laboratories, a long-term temperature and isotopic trend is emerging, with the results pointing to relatively invariant seawater δ18O and generally decreasing seawater temperatures through the Phanerozoic. Uncertainties remain, however, including the effects of reordering of primary clumped isotope compositions via solid-state diffusion of C and O through the mineral lattice at elevated burial temperatures over hundred million year timescales. To develop a quantitative understanding of such reordering, we present data from laboratory heating experiments of late Paleozoic brachiopod calcite. When combined with kinetic models of the reordering reaction, the results of these experiments suggest that burial temperatures less than ~120 °C allow for preservation of primary brachiopod clumped isotope compositions over geological timescales. Analyses of well-preserved Carboniferous and Permian brachiopods reinforce these results by showing that shells with apparent clumped isotope temperatures of ~150 °C are associated with deep sedimentary burial (>5 km), whereas those with putatively primary paleotemperatures in the 10-30 °C range experienced no more than ~1.5 km

  1. Nearest-neighbor nitrogen and oxygen distances in the iron(II)-DNA complex studied by extended X-ray absorption fine structure

    NASA Astrophysics Data System (ADS)

    Bertoncini, Clelia R. A.; Meneghini, Rogerio; Tolentino, Helio

    2010-11-01

    In mammalian cells, DNA-bound Fe(II) reacts with H 2O 2 producing the highly reactive hydroxyl radical ( rad OH) in situ. Since rad OH attacks nearby DNA residue generating oxidative DNA damage, many questions have arisen regarding iron-DNA complex formations and their implication in pre-malignant mutations and aging. In this work, a solid sample of Fe(II)-DNA complex containing one Fe(II) per 10 nucleotides was analyzed from extended X-ray absorption fine structure (EXAFS) spectra collected in a synchrotron radiation light source. Best fitting parameters of the EXAFS signal for the first two shells provide evidence of five oxygen atoms at 1.99 ± 0.02 Å and one nitrogen atom at 2.20 ± 0.02 Å in the inner coordination sphere of the Fe(II)-DNA complex. Considering that both purine base moieties bearing nitrogen atoms are prone to chelate iron, these results are consistent with the previously observed lower levels of DNA damage in cytosine nucleotides relative to adenine and guanine sites in cells under more physiological conditions of Fe(II) Fenton reaction.

  2. An innovative coupling between column leaching and oxygen consumption tests to assess behavior of contaminated marine dredged sediments.

    PubMed

    Couvidat, Julien; Benzaazoua, Mostafa; Chatain, Vincent; Zhang, Fan; Bouzahzah, Hassan

    2015-07-01

    Contaminated dredged sediments are often considered hazardous wastes, so they have to be adequately managed to avoid leaching of pollutants. The mobility of inorganic contaminants is a major concern. Metal sulfides (mainly framboïdal pyrite, copper, and zinc sulfides) have been investigated in this study as an important reactive metal-bearing phase sensitive to atmospheric oxygen action. An oxygen consumption test (OC-Test) has been adapted to assess the reactivity of dredged sediments when exposed to atmospheric oxygen. An experimental column set-up has been developed allowing the coupling between leaching and oxygen consumption test to investigate the reactivity of the sediment. This reactivity, which consisted of sulfide oxidation, was found to occur for saturation degree between 60 and 90 % and until the 20th testing week, through significant sulfates releases. These latter were assumed to come from sulfide oxidation in the first step of the test, then probably from gypsum dissolution. Confrontation results of OC-Test and leachate quality shows that Cu was well correlated to sulfates releases, which in turn, leads to Ca and Mg dissolution (buffer effect). Cu, and mostly Zn, was associated to organic matter, phyllosilicates, and other minerals through organo-clay complexes. This research confirmed that the OC-Test, originally developed for mine tailings, could be a useful tool in the dredged sediment field which can allow for intrinsic characterization of reactivity of a material suspected to readily reacting with oxygen and for better understanding of geochemical processes that affect pollutants behavior, conversion, and transfer in the environment. PMID:25779112

  3. Extended record of 10Be at EPICA Dome C during the last 800 000 years and its synchronization with geomagnetic paleointensity variations from marine sediments

    NASA Astrophysics Data System (ADS)

    Cauquoin, Alexandre; Raisbeck, Grant; Jouzel, Jean; Bard, Edouard; Aster Team

    2013-04-01

    Polar ice cores are exceptional archives that permit the reconstruction of many parameters (variations of temperature, atmospheric composition...) and the reconstitution of the past variations of the Earth climate and environment. They also give access to beryllium-10 (10Be) fallout, an isotope of cosmogenic origin, created by the interaction of Galactic Cosmic Rays (GCR, constituted of high energy charged particles) with the upper atmosphere. The cosmic rays being modulated by solar activity and Earth's magnetic field intensity, the 10Be production is inversely related to the intensity of these two parameters. Most 10Be produced is quickly removed from the atmosphere (residence time in the stratosphere ~1-2 years) and, on the Antarctic plateau, falls mainly by dry deposition as aerosols. So, 10Be can be used as a proxy of paleointensity. It has allowed the improvement of ice cores chronologies thanks to absolute stratigraphic markers linked to excursions and inversions of the geomagnetic field such as the Laschamp excursion [1] or the Matuyama-Brunhes reversal [2, 3]. EPICA Dome C (75° 06' S, 123° 21' E) is a 3270 meter ice core drilled in East Antarctica in the framework of an international project. It offers a complete climate record over the last 800 000 years. As shown at the IPICS 2012 meeting, for the 355 - 800 ka period [4], a continuous high-resolution (11 cm) 10Be profile in this core can be synchronized with continuous variations of paleointensity (PISO-1500) recorded in marine sediments [5] in order to obtain a continuous relative chronology of climate proxies (δD and δ18O respectively) for these two reservoirs. Here, we extend this synchronization down to 269 ka, thus including termination IV and interstadial MIS 9. [1]. Raisbeck et al. (2007) Clim.Past, 3, 541 - 547. [2]. Raisbeck et al. (2006) Nature, 444, 82 - 84. [3]. Dreyfus et al. (2008) Earth and Planet. Sci. Lett., 274, 151 - 156. [4]. G.Raisbeck et al. (2012) IPICS Open Science Conference

  4. Mapping for Advocacy - Using Marine Geophysical Data to Establish the Limits of Extend Continent Shelves under the Convention on the Law of the Sea.

    NASA Astrophysics Data System (ADS)

    Coakley, B.; Baker, B.

    2008-12-01

    Politics and science do not comfortably mesh. Article 76 of the Law of the Sea Convention is an example of a negotiated compromise included in the treaty to serve conflicting state interests between the "haves" (broad continental shelves) and "have-nots" (narrow or no shelf). The language lays out procedures for coastal states to establish extended exploitation rights over seabed resources beyond their EEZ. The rules written into article 76 are about simple, measurable quantities from geodesy (position), hydrography (depth) and marine geology (sediment thickness). With a data set in hand, it is possible to come up with a document that could, with assigned numerical uncertainty (position, depth and sediment thickness +/- so many meters), apply the rules and establish a plausible claim based entirely on morphology. The art in this process arises primarily because of a single expression; natural prolongation. Prolongation is simple enough, but what is natural? By one reading, a natural prolongation shares the continental character of the material underlying the shelves. This fits with the basic distinction between continents and oceans from plate tectonics. The recognition that one did not transmute into another was one of the basic insights on the road to our present understanding of the mobile earth surface. It also fits with the basic distinction that underlies the LOS treaty, the shelves and slopes within 200 miles of land are to be administered by coastal states, while the deep ocean seabed and subsoil and their resources belong to mankind as a whole. Drafted and discussed more than 30 years ago, Article 76 is innocent about what has been learned over the past few decades since the treaty was signed in 1982. The distinction between continental and ocean crust has been blurred by a complex array of hybrids that complicate this determination (eg. oceanic plateaus, hyper-extended continental crust, etc.). Article 76 was written at a time when narrow-beam bottom

  5. Oxygen uptake kinetics and maximal aerobic power are unaffected by inspiratory muscle training in healthy subjects where time to exhaustion is extended.

    PubMed

    Edwards, A M; Cooke, C B

    2004-10-01

    The aim of this study was to determine whether 4 weeks of inspiratory muscle training (IMT) would be accompanied by alteration in cardiopulmonary fitness as assessed through moderate intensity oxygen uptake (V(.)O(2)) kinetics and maximal aerobic power (V(.)O(2max)). Eighteen healthy males agreed to participate in the study [training group (Tra) n=10, control group (Con) n=8]. Measurements of spirometry and maximal static inspiratory mouth pressure ( PI(max)) were taken pre- and post-training in addition to: (1) an incremental test to volitional exhaustion, (2) three square-wave transitions from walking to running at a moderate intensity (80% ventilatory threshold) and (3) a maximal aerobic constant-load running test to volitional fatigue for the determination of time to exhaustion ( T(lim)). Training was performed using an inspiratory muscle trainer (Powerbreathe). There were no significant differences in spirometry either between the two groups or when comparing the post- to pre-training results within each group. Mean PI(max) increased significantly in Tra ( P<0.01) and showed a trend for improvement ( P<0.08) in Con. Post-training T(lim) was significantly extended in both Tra [232.4 (22.8) s and 242.8 (20.1) s] ( P<0.01) and Con [224.5 (19.6) and 233.5 (12.7) s] ( P<0.05). Post-training T(lim) was significantly extended in Tra compared to Con ( P<0.05). In conclusion, the most plausible explanation for the stability in V(.)O(2) kinetics and V(.)O(2max) following IMT is that it is due to insufficient whole-body stress to elicit either central or peripheral cardiopulmonary adaptation. The extension of post-training T(lim) suggests that IMT might be useful as a stratagem for producing greater volumes of endurance work at high ventilatory loads, which in turn could improve cardiopulmonary fitness. PMID:15322855

  6. Novel Eukaryotic Lineages Inferred from Small-Subunit rRNA Analyses of Oxygen-Depleted Marine Environments†

    PubMed Central

    Stoeck, Thorsten; Epstein, Slava

    2003-01-01

    Microeukaryotes in oxygen-depleted environments are among the most diverse, as well as the least studied, organisms. We conducted a cultivation-independent, small-subunit (SSU) rRNA-based survey of microeukaryotes in suboxic waters and anoxic sediments in the great Sippewisset salt marsh, Cape Cod, Mass. We generated two clone libraries and analyzed approximately 300 clones, which contained a large diversity of microeukaryotic SSU rRNA signatures. Only a few of these signatures were closely related (sequence similarity of >97%) to the sequences reported earlier. The bulk of our sequences represented deep novel branches within green algae, fungi, cercozoa, stramenopiles, alveolates, euglenozoa and unclassified flagellates. In addition, a significant number of detected rRNA sequences exhibited no affiliation to known organisms and sequences and thus represent novel lineages of the highest taxonomical order, most of them branching off the base of the global phylogenetic tree. This suggests that oxygen-depleted environments harbor diverse communities of novel organisms, which may provide an interesting window into the early evolution of eukaryotes. PMID:12732534

  7. Oxygen-Poor Microzones as Potential Sites of Microbial N2 Fixation in Nitrogen-Depleted Aerobic Marine Waters

    PubMed Central

    Paerl, Hans W.; Prufert, Leslie E.

    1987-01-01

    The nitrogen-deficient coastal waters of North Carolina contain suspended bacteria potentially able to fix N2. Bioassays aimed at identifying environmental factors controlling the development and proliferation of N2 fixation showed that dissolved organic carbon (as simple sugars and sugar alcohols) and particulate organic carbon (derived from Spartina alterniflora) additions elicited and enhanced N2 fixation (nitrogenase activity) in these waters. Nitrogenase activity occurred in samples containing flocculent, mucilage-covered bacterial aggregates. Cyanobacterium-bacterium aggregates also revealed N2 fixation. In all cases bacterial N2 fixation occurred in association with surficial microenvironments or microzones. Since nitrogenase is oxygen labile, we hypothesized that the aggregates themselves protected their constituent microbes from O2. Microelectrode O2 profiles revealed that aggregates had lower internal O2 tensions than surrounding waters. Tetrazolium salt (2,3,5-triphenyl-3-tetrazolium chloride) reduction revealed that patchy zones existed both within microbes and extracellularly in the mucilage surrounding microbes where free O2 was excluded. Triphenyltetrazolium chloride reduction also strongly inhibited nitrogenase activity. These findings suggest that N2 fixation is mediated by the availability of the appropriate types of reduced microzones. Organic carbon enrichment appears to serve as an energy and structural source for aggregate formation, both of which were required for eliciting N2 fixation responses of these waters. Images PMID:16347337

  8. High-sensitivity extended-gate field-effect transistors as pH sensors with oxygen-modified reduced graphene oxide films coated on different reverse-pyramid silicon structures as sensing heads

    NASA Astrophysics Data System (ADS)

    Li, Yu-Ren; Chang, Shih-hsueh; Chang, Chia-Tsung; Tsai, Wan-Lin; Chiu, Yu-Kai; Yang, Po-Yu; Cheng, Huang-Chung

    2016-04-01

    A high-performance extended-gate field-effect transistor (EGFET) as pH sensor with its microstructured sensing head composed of an oxygen-modified reduced graphene oxide film (RGOF) on a reverse-pyramid (RP) Si structure was developed to achieve a high sensitivity of 57.5 mV/pH with an excellent linearity of 0.9929 in a wide pH sensing range of 1-13. These features were ascribed to the large amount of sensing sites and large sensing area. In contrast, the planar Si substrate with the oxygen-plasma-treated RGOF (OPT-RGOF) at the optimal bias power showed a sensitivity of 52.9 mV/pH compared with 45.0 mV/pH for that without plasma treatment. It reveals that oxygen plasma can produce oxygen-containing groups as sensing sites, enhancing proton sensing characteristics. However, oxygen plasma treatment at high bias powers would cause damage to the RGOFs, resulting in poor conducting and sensing properties. On the other hand, the use of the RP structures could increase the effective sensing area and further promote the sensing performance.

  9. Upper thermal tolerance and oxygen limitation in terrestrial arthropods.

    PubMed

    Klok, C Jaco; Sinclair, Brent J; Chown, Steven L

    2004-06-01

    The hypothesis of oxygen limitation of thermal tolerance proposes that critical temperatures are set by a transition to anaerobic metabolism, and that upper and lower tolerances are therefore coupled. Moreover, this hypothesis has been dubbed a unifying general principle and extended from marine to terrestrial ectotherms. By contrast, in insects the upper and lower limits are decoupled, suggesting that the oxygen limitation hypothesis might not be as general as proposed. However, no direct tests of this hypothesis or its predictions have been undertaken in terrestrial species. We use a terrestrial isopod (Armadillidium vulgare) and a tenebrionid beetle (Gonocephalum simplex) to test the prediction that thermal tolerance should vary with oxygen partial pressure. Whilst in the isopod critical thermal maximum declined with declining oxygen concentration, this was not the case in the beetle. Efficient oxygen delivery via a tracheal system makes oxygen limitation of thermal tolerance, at a whole organism level, unlikely in insects. By contrast, oxygen limitation of thermal tolerances is expected to apply to species, like the isopod, in which the circulatory system contributes significantly to oxygen delivery. Because insects dominate terrestrial systems, oxygen limitation of thermal tolerance cannot be considered pervasive in this habitat, although it is a characteristic of marine species. PMID:15159440

  10. Marine biogeochemistry: Methylmercury manufacture

    NASA Astrophysics Data System (ADS)

    Cossa, Daniel

    2013-10-01

    The neurotoxin methylmercury can accumulate in marine food webs, contaminating seafood. An analysis of the isotopic composition of fish in the North Pacific suggests that much of the mercury that enters the marine food web originates from low-oxygen subsurface waters.

  11. Correlating carbon and oxygen isotope events in early to middle Miocene shallow marine carbonates in the Mediterranean region using orbitally tuned chemostratigraphy and lithostratigraphy

    PubMed Central

    Piller, Werner E.; Reuter, Markus; Harzhauser, Mathias

    2015-01-01

    Abstract During the Miocene prominent oxygen isotope events (Mi‐events) reflect major changes in glaciation, while carbonate isotope maxima (CM‐events) reflect changes in organic carbon burial, particularly during the Monterey carbon isotope excursion. However, despite their importance to the global climate history they have never been recorded in shallow marine carbonate successions. The Decontra section on the Maiella Platform (central Apennines, Italy), however, allows to resolve them for the first time in such a setting during the early to middle Miocene. The present study improves the stratigraphic resolution of parts of the Decontra section via orbital tuning of high‐resolution gamma ray (GR) and magnetic susceptibility data to the 405 kyr eccentricity metronome. The tuning allows, within the established biostratigraphic, sequence stratigraphic, and isotope stratigraphic frameworks, a precise correlation of the Decontra section with pelagic records of the Mediterranean region, as well as the global paleoclimatic record and the global sea level curve. Spectral series analyses of GR data further indicate that the 405 kyr orbital cycle is particularly well preserved during the Monterey Event. Since GR is a direct proxy for authigenic uranium precipitation during increased burial of organic carbon in the Decontra section, it follows the same long‐term orbital pacing as observed in the carbon isotope records. The 405 kyr GR beat is thus correlated with the carbon isotope maxima observed during the Monterey Event. Finally, the Mi‐events can now be recognized in the δ18O record and coincide with plankton‐rich, siliceous, or phosphatic horizons in the lithology of the section. PMID:27546980

  12. Density functional theory study on oxygen adsorption in LaSrCoO 4: An extended cathode material for solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zhou, Jun; Chen, Gang; Wu, Kai; Cheng, Yonghong; Peng, Bo; Guo, Jiaojiao; Jiang, Yizhe

    2012-01-01

    Solid oxide fuel cell (SOFC) is one of the most promising technologies for a clean and secure source of energy in future due to its high energy efficiency and outstanding fuel flexibility. The search for new materials operating at low-temperature in order to make SOFCs economically competitive is a great challenge facing us today. In this report, atomistic computer simulation based on density functional theory (DFT) has been used to predict the formation of oxygen vacancy and the strong oxygen adsorption kinetics mechanisms in LaSrCoO4. The optimal adsorption configurations as well as the adsorption energies for oxygen molecule adsorption on various sites of LaSrCoO4 (0 1 0) surface were derived. Furthermore, a strong hybridization between Co and O and shorter Co-O bond length for molecular adsorption were obtained by analysis of density of states. The calculated results imply that LaSrCoO4 could serve as possible cathode material due to its low formation and migration energies of oxygen vacancies.

  13. Oxygen Radical Scavenger Activity, EPR, NMR, Molecular Mechanics and Extended-Hückel Molecular Orbital Investigation of the Bis(Piroxicam)Copper(II) Complex.

    PubMed

    Cini, R; Pogni, R; Basosi, R; Donati, A; Rossi, C; Sabadini, L; Rollo, L; Lorenzini, S; Gelli, R; Marcolongo, R

    1995-01-01

    The oxygen radical scavenger activity (ORSA) of [Cu(II)(Pir)(2)] (HPir = Piroxicam = 4-hydroxy -2- methyl -N-2- pyridyl -2H- 1,2-benzothiazine -3- carboxamide 1,1-dioxide) was determined by chemiluminescence of samples obtained by mixing human neutrophils (from healthy subjects) and [Cu(II)(Pir)(2)(DMF)(2)] (DMF = N,N -dimethylformammide) in DMSO/GLY/PBS (2:1:2, v/v) solution (DMSO = dimethylsulfoxide, GLY = 1,2,3-propantriol, PBS = Dulbecco's buffer salt solution). The ratio of the residual radicals, for the HPir (1.02.10(-4)M) and [Cu(II)(Pir)(2)(DMF)(2)] (1.08.10(-5)M)/HPir (8.01.10-(-5)M) systems was higher than 12 (not stimulated) [excess of piroxicam was added (Cu/Pir molar ratio approximately 1:10) in order to have most of the metal complexed as bischelate]. In contrast, the ratio of residual radicals for the CuCl(2) (1.00.10(-5)M) and [Cu(II)(Pir)(2)(DMF)(2)] (1.08.10(-5)M)/Hpir (8.01.10(-5)M)system was 5. The [Cu(II)(Pir)(2)] compound is therefore a stronger radical scavenger than either HPir or CuCl(2). A molecular mechanics (MM) analysis of the gas phase structures of neutral HPir, its zwitterionic (HPir(+-)) and anionic (Pir(-)) forms, and some Cu(II)-piroxicam complexes based on X-ray structures allowed calculation of force constants. The most stable structure for HPir has a ZZZ conformation similar to that found in the Cu(II) (and Cd(II) complexes) in the solid state as well as in the gas phase. The structure is stabilized by a strong H bond which involves the N(amide)-H and O(enolic) groups. The MM simulation for the [Cu(II)(Pir)(2)(DMF)(2)] complex showed that two high repulsive intramolecular contacts exist between a pyridyl hydrogen atom of one Pir(-) molecule with the O donor of the other ligand. These interactions activate a transition toward a pseudo-tetrahedral geometry, in the case the apical ligands are removed. On refluxing a suspension of [Cu(II)(Pir)(2)(DMF)(2)] in acetone a brown microcystalline solid with the Cu(Pir)(2).0.5DMF

  14. S-band radio occultation measurements of the atmosphere and topography of Mars with Mariner 9: Extended mission coverage of polar and intermediate latitudes

    NASA Technical Reports Server (NTRS)

    Kliore, A. J.; Fjeldbo, G.; Seidel, B. L.; Sykes, M. J.; Woiceshyn, P. M.

    1973-01-01

    Radio occultation measurements from Mariner 9 orbits around Mars show that the radius of Mars changes by only about 2 km from a latitude of 65 deg to the north pole, that the north polar area is about average in elevation, and that polar temperature profiles are indicative of the possibility that the remnant north polar cap may be at least partially composed of water ice. It is also found that Mars, in addition to being asymmetrical equatorially, is also significantly asymmetrical in the north and south direction with the Southern Hemisphere lying 3 to 4 km higher. Temperature gradients in the clear Martian atmosphere of only about one-half of the adiabatic gradients of 5 deg K/km suggest the importance of dynamical processes.

  15. Peroxisomes Extend Peroxules in a Fast Response to Stress via a Reactive Oxygen Species-Mediated Induction of the Peroxin PEX11a1[OPEN

    PubMed Central

    Rodríguez-Serrano, María; Sanz-Fernández, María

    2016-01-01

    Peroxisomes are highly dynamic and metabolically active organelles that play an important role in cellular functions, including reactive oxygen species (ROS) metabolism. Peroxisomal dynamics, such as the proliferation, movement, and production of dynamic extensions called peroxules, have been associated with ROS in plant cells. However, the function and regulation of peroxules are largely unknown. Using confocal microscopy, we have shown that treatment of Arabidopsis leaves with the heavy metal cadmium produces time course-dependent changes in peroxisomal dynamics, starting with peroxule formation, followed by peroxisome proliferation, and finally returning to the normal morphology and number. These changes during Cd treatment were regulated by NADPH oxidase (C and F)-related ROS production. Peroxule formation is a general response to stimuli such as arsenic and is regulated by peroxin 11a (PEX11a), as Arabidopsis pex11a RNAi lines are unable to produce peroxules under stress conditions. The pex11a line showed higher levels of lipid peroxidation content and lower expression of genes involved in antioxidative defenses and signaling, suggesting that these extensions are involved in regulating ROS accumulation and ROS-dependent gene expression in response to stress. Our results demonstrate that PEX11a and peroxule formation play a key role in regulating stress perception and fast cell responses to environmental cues. PMID:27208303

  16. Peroxisomes Extend Peroxules in a Fast Response to Stress via a Reactive Oxygen Species-Mediated Induction of the Peroxin PEX11a.

    PubMed

    Rodríguez-Serrano, María; Romero-Puertas, María C; Sanz-Fernández, María; Hu, Jianping; Sandalio, Luisa M

    2016-07-01

    Peroxisomes are highly dynamic and metabolically active organelles that play an important role in cellular functions, including reactive oxygen species (ROS) metabolism. Peroxisomal dynamics, such as the proliferation, movement, and production of dynamic extensions called peroxules, have been associated with ROS in plant cells. However, the function and regulation of peroxules are largely unknown. Using confocal microscopy, we have shown that treatment of Arabidopsis leaves with the heavy metal cadmium produces time course-dependent changes in peroxisomal dynamics, starting with peroxule formation, followed by peroxisome proliferation, and finally returning to the normal morphology and number. These changes during Cd treatment were regulated by NADPH oxidase (C and F)-related ROS production. Peroxule formation is a general response to stimuli such as arsenic and is regulated by peroxin 11a (PEX11a), as Arabidopsis pex11a RNAi lines are unable to produce peroxules under stress conditions. The pex11a line showed higher levels of lipid peroxidation content and lower expression of genes involved in antioxidative defenses and signaling, suggesting that these extensions are involved in regulating ROS accumulation and ROS-dependent gene expression in response to stress. Our results demonstrate that PEX11a and peroxule formation play a key role in regulating stress perception and fast cell responses to environmental cues. PMID:27208303

  17. Dissolved Organic In Natural and Polluted Waters: Methodology and Results of Running Control of Chemical Oxygen Demand (cod) For The Inland and Marine Aquatic System

    NASA Astrophysics Data System (ADS)

    Melentyev, K. V.; Worontsov, A. M.

    Current control of dissolved organic matter in natural and waste waters is the definition traditionally of chemical oxygen demand (COD) -- one of the basic parameters of quality of water. According to the International Standard (ISO 6060), it requires not less than one hour, while in many cases the operative information about amount of dissolved organic matter in aquatic environments have importance for prevention of an emergency. The standard method is applicable to waters with meaning of COD above 30 mg O2/l and, as the chloride ion prevents, it could be difficult for assessment of organic matter in sea water. Besides it is based on dichromate oxidation of the sum of organic substances in strong acid conditions at the presence of silver and mercury, that resulted in formation toxic pollutants. Till now attempts of automation of the COD definition in aquatic system were limited, basically, to duplication of the technology submitted the above standard (automatic COD analyzers "SERES Co."-- France, or "Tsvet Co." - Russia). The system of ozone-chemiluminescence automatic control of organic matter in water (CS COD) is offered and designed. Its based on the ozone oxidation of these substances in flowing water system and measurement arising from luminescent effects. CS COD works in real time. An instrument uses for reaction the atmospheric air, doesn't require fill of reagents and doesn't make new toxic pollutants. The system was tested in laboratory, and biochemical control of organic matter in water samples gathered from the river Neva and other polluted inland water areas and basins in St. Petersburg region was fulfilled (distilled water was used as "zero" media). The results of systematization of these measurements are presented. The new special ozone generator and flowing reactor for real-time running control of different waters in natural conditions were developed, and several series of large - scale field experiments onboard research ship were provided

  18. Solid state oxygen sensor

    DOEpatents

    Garzon, Fernando H.; Brosha, Eric L.

    1997-01-01

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures.

  19. Extending the family of oxygen ion conductors isostructural with La{sub 2}Mo{sub 2}O{sub 9}

    SciTech Connect

    Voronkova, V.I.; Kharitonova, E.P.; Orlova, E.I.; Belov, D.A.

    2012-12-15

    X-ray diffraction characterization of materials prepared by solid-state reactions in the ternary systems La{sub 2}Mo{sub 2}O{sub 9}-Nd{sub 2}W{sub 2}O{sub 9}-'Nd{sub 2}Mo{sub 2}O{sub 9}{sup '} and La{sub 2}Mo{sub 2}O{sub 9}-Pr{sub 2}W{sub 2}O{sub 9}-Pr{sub 2}Mo{sub 2}O{sub 9} has shown that, in these systems, compounds isostructural with the oxygen ion conductor La{sub 2}Mo{sub 2}O{sub 9} exist in wide single-phase regions. Partial tungsten substitution for molybdenum may yield stable Ln{sub 2}Mo{sub 2-2x}W{sub 2x}O{sub 9} compounds with the La{sub 2}Mo{sub 2}O{sub 9} structure, where Ln is a rare-earth element different from lanthanum and praseodymium, e.g., neodymium. Tungsten also stabilizes Pr{sub 2}Mo{sub 2}O{sub 9}, which otherwise decomposes above 700 Degree-Sign C. A series of continuous solid solution was found in the La{sub 2}Mo{sub 2}O{sub 9}-Pr{sub 2}Mo{sub 2}O{sub 9} system. Polymorphism of compounds existing in the above ternary systems was studied by differential scanning calorimetry. The conductivity of most of the compounds studied approaches that of lanthanum molybdate. - Graphical abstract: La{sub 2}Mo{sub 2}O{sub 9}-Nd{sub 2}W{sub 2}O{sub 9}-''Nd{sub 2}Mo{sub 2}O{sub 9}'' and La{sub 2}Mo{sub 2}O{sub 9}-Pr{sub 2}W{sub 2}O{sub 9}-Pr{sub 2}Mo{sub 2}O{sub 9} phase diagrams. Single-phase regions of compounds with the La{sub 2}Mo{sub 2}O{sub 9} and Nd{sub 2}W{sub 2}O{sub 9} (Pr{sub 2}W{sub 2}O{sub 9}) structures are highlighted in blue and red. Highlights: Black-Right-Pointing-Pointer Phase formation in the La{sub 2}Mo{sub 2}O{sub 9}-Pr{sub 2}W{sub 2}O{sub 9}-Pr{sub 2}Mo{sub 2}O{sub 9} system has been studied. Black-Right-Pointing-Pointer Phase formation in the La{sub 2}Mo{sub 2}O{sub 9}-Nd{sub 2}W{sub 2}O{sub 9}-'Nd{sub 2}Mo{sub 2}O{sub 9}' system has been studied. Black-Right-Pointing-Pointer Compounds isostructural with La{sub 2}Mo{sub 2}O{sub 9} were found in wide single-phase regions. Black-Right-Pointing-Pointer Tungsten stabilizes Nd{sub 2}Mo

  20. Dissolved Organic In Natural and Polluted Waters: Methodology and Results of Running Control of Chemical Oxygen Demand (cod) For The Inland and Marine Aquatic System

    NASA Astrophysics Data System (ADS)

    Melentyev, K. V.; Worontsov, A. M.

    Current control of dissolved organic matter in natural and waste waters is the definition traditionally of chemical oxygen demand (COD) -- one of the basic parameters of quality of water. According to the International Standard (ISO 6060), it requires not less than one hour, while in many cases the operative information about amount of dissolved organic matter in aquatic environments have importance for prevention of an emergency. The standard method is applicable to waters with meaning of COD above 30 mg O2/l and, as the chloride ion prevents, it could be difficult for assessment of organic matter in sea water. Besides it is based on dichromate oxidation of the sum of organic substances in strong acid conditions at the presence of silver and mercury, that resulted in formation toxic pollutants. Till now attempts of automation of the COD definition in aquatic system were limited, basically, to duplication of the technology submitted the above standard (automatic COD analyzers "SERES Co."-- France, or "Tsvet Co." - Russia). The system of ozone-chemiluminescence automatic control of organic matter in water (CS COD) is offered and designed. Its based on the ozone oxidation of these substances in flowing water system and measurement arising from luminescent effects. CS COD works in real time. An instrument uses for reaction the atmospheric air, doesn't require fill of reagents and doesn't make new toxic pollutants. The system was tested in laboratory, and biochemical control of organic matter in water samples gathered from the river Neva and other polluted inland water areas and basins in St. Petersburg region was fulfilled (distilled water was used as "zero" media). The results of systematization of these measurements are presented. The new special ozone generator and flowing reactor for real-time running control of different waters in natural conditions were developed, and several series of large - scale field experiments onboard research ship were provided

  1. Bottom-Water Conditions in a Marine Basin after the Cretaceous–Paleogene Impact Event: Timing the Recovery of Oxygen Levels and Productivity

    PubMed Central

    Sosa-Montes De Oca, Claudia; Martínez-Ruiz, Francisca; Rodríguez-Tovar, Francisco Javier

    2013-01-01

    An ultra-high-resolution analysis of major and trace element contents from the Cretaceous–Paleogene boundary interval in the Caravaca section, southeast Spain, reveals a quick recovery of depositional conditions after the impact event. Enrichment/depletion profiles of redox sensitive elements indicate significant geochemical anomalies just within the boundary ejecta layer, supporting an instantaneous recovery –some 102 years– of pre-impact conditions in terms of oxygenation. Geochemical redox proxies point to oxygen levels comparable to those at the end of the Cretaceous shortly after impact, which is further evidenced by the contemporary macrobenthic colonization of opportunistic tracemakers. Recovery of the oxygen conditions was therefore several orders shorter than traditional proposals (104–105 years), suggesting a probable rapid recovery of deep-sea ecosystems at bottom and in intermediate waters. PMID:24349232

  2. Modeling the signal transfer of sea water δ18O to the δ18O of atmospheric oxygen using a diagnostic box model for the terrestrial and marine biosphere

    NASA Astrophysics Data System (ADS)

    Leuenberger, Markus C.

    1997-11-01

    We make use of a simple diagnostic box model to determine the sensitivities of the influencing parameters for the isotopic signal transfer of seawater oxygen to atmospheric oxygen. We calculate the δ18O of atmospheric oxygen from prescribed oxygen fluxes of the living and dead biomes on land and in the ocean, respectively. The model is driven by an assumed (experiment 1) or measured (experiments 2 and 3) temporal seawater δ18O signal and a land biomass estimation. In experiment 1, we calculated the required changes of several model parameters in order to study fast variations of δ18O of atmospheric oxygen as seen in the Greenland Ice Core Project (GRIP) ice at depths assigned to the Eemian time period. Our calculations support evidence of stratigraphic problems at these depths in the GRIP ice core. In experiment 2, we adjusted the model output, which was driven by the benthic seawater δ18O record from V19-30, to the measured Greenland Ice Sheet Project 2 δ18O record of atmospheric oxygen for the last 110,000 years, by varying the model parameter. Single and multi-parameter matchings were performed. The results for single-parameter runs exceed the uncertainty ranges for most of the parameters, while multiparameter variations are well within these ranges. The model calculations are most sensitive to the land respiration factor. Our results support the findings of Van de Water et al. [1994] that the fractionations associated with biomes activities were most probably lower during cold periods, which could point to a combination of fractionations with different temperature dependencies. The model results indicate periods of higher marine biological activity during the ice age than today. Temporal variations of the model parameters show a double peak around 10000 and 8000 years ago, which could be associated with meltwater pulses, as shown in experiment 3. However, they are hardly the well-known Fairbanks [Fairbanks et al., 1992] pulses since these occur 3000 to

  3. Micro-trace fossils reveal pervasive reworking of Pliocene sapropels by low-oxygen-adapted benthic meiofauna

    NASA Astrophysics Data System (ADS)

    Löhr, S. C.; Kennedy, M. J.

    2015-03-01

    Animal burrowers leave an indelible signature on the sedimentary record in most marine environments, with the seeming exception of low-oxygen environments. In modern sedimentary settings, however, sub-millimetre-sized benthic animals (meiofauna) are adapted to low oxygen and even sulfidic conditions. Almost nothing is known about their impact on ancient marine sediments because they leave few recognizable traces. Here we show, in classic Pliocene-aged anoxic facies from the Mediterranean, the first reported trace fossil evidence of meiofaunal activity and its relation to changing oxygenation. A novel approach utilizing electron imaging of ion-polished samples shows that meiofauna pervasively reworked sediment under oxygen-depleted conditions that excluded macrofauna, fragmenting organic laminae and emplacing 15- to 70-μm-diameter faecal pellets without macroscopically influencing the fabric. The extent of reworking raises the question: how pervasively altered are other sediments presently assumed to lack animal influence and how far into the geological record does this influence extend?

  4. Measuring Dissolved Oxygen Quantitatively. Collecting and Cultivating Marine Bacteria. To Recognize, Record, and Analyze Characteristics of a Sandy Beach Environment. Quantitative and Qualitative Analysis of Phosphate in Water. Learning Experiences for Coastal and Oceanic Awareness Studies, Nos. 307, 309, 310, 313. [Project COAST].

    ERIC Educational Resources Information Center

    Delaware Univ., Newark. Coll. of Education.

    Included are four activity units: (1) Measuring Dissolved Oxygen Quantitatively; (2) Collecting and Cultivating Marine Bacteria; (3) To Recognize, Record, and Analyze Characteristics of a Sandy Beach Environment; and (4) Quantitative and Qualitative Analysis of Phosphate in Water. All the activities are designed to be used by secondary school…

  5. Recycled oceanic crust and marine sediment in the source of alkali basalts in Shandong, eastern China: Evidence from magma water content and oxygen isotopes

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Xia, Qun-Ke; Deloule, Etienne; Chen, Huan; Feng, Min

    2015-12-01

    The magma water contents and cpx δ18O values in alkali basalts from the Fuyanyshan (FYS) volcano in Shandong, eastern China, were investigated by an inverse calculation based on the water content of clinopyroxene (cpx) phenocrysts, the ivAlcpx-dependent water partitioning coefficient Dwatercpx>/melt, and secondary ion mass spectrometer, respectively. The calculated water content (H2O wt.) of magma ranges from 0.58% to 3.89%. It positively correlates with heavy rare earth element concentrations and bulk rock 87Sr/86Sr ratios, and it negatively correlates with Nb/U ratios. However, it is not correlated with bulk Mg# (Mg# = 100 × Mg / (Mg + Fe)) and (La/Yb)n (n represents primitive mantle normalization). Combined with the rather homogenous distribution of water content within cpx grains, these correlations indicate that the water variations among different samples represent the original magma signature, rather than results of a shallow process, such as degassing and diffusion. The δ18O of cpx phenocrysts varies from 3.6‰ to 6.3‰ (±0.5‰, 2SD), which may be best explained by the involvement of components from the lower and upper oceanic crust with marine sediments within the mantle source. The H2O/Ce ratios of the calculated melts range from 113 to 696 and form a positive trend with bulk rock 87Sr/86Sr, which cannot be explained by the recycled Sulu eclogite or by the metasomatized lithospheric mantle. Our modeling calculation shows that the decoupling of ɛHf and ɛNd could be caused by the involvement of marine sediments. Combing the high Ba/Th ratios, positive Sr spikes, and low Ce/Pb ratios for the Fuyanshan basalts, we suggest that the hydrous nature of the FYS basalts was derived from the hydrous mantle transition zone with ancient sediments.

  6. Marine fragrance chemistry.

    PubMed

    Hügel, Helmut M; Drevermann, Britta; Lingham, Anthony R; Marriott, Philip J

    2008-06-01

    The main marine message in perfumery is projected by Calone 1951 (7-methyl-2H-1,5-benzodioxepin-3(4H)-one). Kraft (Givaudan) and Gaudin (Firmenich) further maximized the marine fragrance molecular membership by extending the carbon chain of the 7-Me group. Our research targeted the polar group of the benzodioxepinone parent compound to investigate how this region of molecular makeup resonates with the dominant marine fragrance of the Calone 1951 structure. The olfactory evaluation of analogues prepared by chemical modification or removal of the CO group resulted in the introduction of aldehydic, sweet and floral-fruity notes with a diluted/diminished potency of the marine odor. To further analyze the olfactory properties of benzodioxepinones containing a diverse range of aromatic ring substituents, a novel synthesis route was developed. We found that a 7-alkyl group in Calone 1951 was essential for the maintenance of the significant marine odor characteristic, and our studies support the concept that the odorant structure occupying the hydrophobic binding pocket adjacent to the aromatic ring-binding site of the olfactory receptor is pivotal in the design and discovery of more potent and characteristic marine fragrances. How the structure of benzodioxepinones connects to marine sea-breeze fragrances is our continuing challenging research focus at the chemistry-biology interface. PMID:18618392

  7. Structured Multiple Endosymbiosis of Bacteria and Archaea in a Ciliate from Marine Sulfidic Sediments: A Survival Mechanism in Low Oxygen, Sulfidic Sediments?

    PubMed Central

    Edgcomb, Virginia P.; Leadbetter, Edward R.; Bourland, William; Beaudoin, David; Bernhard, Joan M.

    2011-01-01

    Marine micro-oxic to sulfidic environments are sites of intensive biogeochemical cycling and elemental sequestration, where prokaryotes are major driving forces mediating carbon, nitrogen, sulfur, phosphorus, and metal cycles, important from both biogeochemical and evolutionary perspectives. Associations between single-celled eukaryotes and bacteria and/or archaea are common in such habitats. Here we describe a ciliate common in the micro-oxic to anoxic, typically sulfidic, sediments of Santa Barbara Basin (CA, USA). The ciliate is 95% similar to Parduzcia orbis (18S rRNA). Transmission electron micrographs reveal clusters of at least three different endobiont types organized within membrane-bound sub-cellular regions. Catalyzed reporter deposition–fluorescent in situ hybridization and 16S rRNA clone libraries confirm the symbionts include up to two sulfate reducers (Desulfobulbaceae, Desulfobacteraceae), a methanogen (Methanobacteriales), and possibly a Bacteroidete (Cytophaga) and a Type I methanotroph, suggesting synergistic metabolisms in this environment. This case study is discussed in terms of implications to biogeochemistry, and benthic ecology. PMID:21833311

  8. Oxygen Therapy

    MedlinePlus

    Oxygen therapy is a treatment that provides you with extra oxygen. Oxygen is a gas that your body needs to function. Normally, your lungs absorb oxygen from the air you breathe. But some conditions ...

  9. Solid state oxygen sensor

    DOEpatents

    Garzon, F.H.; Brosha, E.L.

    1997-12-09

    A potentiometric oxygen sensor is formed having a logarithmic response to a differential oxygen concentration while operating as a Nernstian-type sensor. Very thin films of mixed conducting oxide materials form electrode services while permitting diffusional oxygen access to the interface between the zirconia electrolyte and the electrode. Diffusion of oxygen through the mixed oxide is not rate-limiting. Metal electrodes are not used so that morphological changes in the electrode structure do not occur during extended operation at elevated temperatures. 6 figs.

  10. Can Oxygen Set Thermal Limits in an Insect and Drive Gigantism?

    PubMed Central

    Verberk, Wilco C. E. P.; Bilton, David T.

    2011-01-01

    Background Thermal limits may arise through a mismatch between oxygen supply and demand in a range of animal taxa. Whilst this oxygen limitation hypothesis is supported by data from a range of marine fish and invertebrates, its generality remains contentious. In particular, it is unclear whether oxygen limitation determines thermal extremes in tracheated arthropods, where oxygen limitation may be unlikely due to the efficiency and plasticity of tracheal systems in supplying oxygen directly to metabolically active tissues. Although terrestrial taxa with open tracheal systems may not be prone to oxygen limitation, species may be affected during other life-history stages, particularly if these rely on diffusion into closed tracheal systems. Furthermore, a central role for oxygen limitation in insects is envisaged within a parallel line of research focussing on insect gigantism in the late Palaeozoic. Methodology/Principal Findings Here we examine thermal maxima in the aquatic life stages of an insect at normoxia, hypoxia (14 kPa) and hyperoxia (36 kPa). We demonstrate that upper thermal limits do indeed respond to external oxygen supply in the aquatic life stages of the stonefly Dinocras cephalotes, suggesting that the critical thermal limits of such aquatic larvae are set by oxygen limitation. This could result from impeded oxygen delivery, or limited oxygen regulatory capacity, both of which have implications for our understanding of the limits to insect body size and how these are influenced by atmospheric oxygen levels. Conclusions/Significance These findings extend the generality of the hypothesis of oxygen limitation of thermal tolerance, suggest that oxygen constraints on body size may be stronger in aquatic environments, and that oxygen toxicity may have actively selected for gigantism in the aquatic stages of Carboniferous arthropods. PMID:21818347

  11. Mixotrophic growth of bacteriochlorophyll a-containing members of the OM60/NOR5 clade of marine gammaproteobacteria is carbon-starvation independent and correlates with the type of carbon source and oxygen availability

    PubMed Central

    2013-01-01

    Background Populations of aerobic anoxygenic photoheterotrophic bacteria in marine environments are dominated by members of the Roseobacter lineage within the Alphaproteobacteria and the OM60/NOR5 clade of gammaproteobacteria. A wealth of information exists about the regulation of pigment production and mixotrophic growth in various members of the Roseobacter clade, but a detailed knowledge about aerobic bacteriochlorophyll a-containing gammaproteobacteria is still limited to one strain of the species Congregibacter litoralis. Results The production of photosynthetic pigments and light-dependent mixotrophic growth was analysed in Luminiphilus syltensis DSM 22749T, Chromatocurvus halotolerans DSM 23344T and Pseudohaliea rubra DSM 19751T, representing three taxonomically diverse strains of bacteriochlorophyll a-containing gammaproteobacteria affiliated to the OM60/NOR5 clade. In these strains the expression of a photosynthetic apparatus depended mainly on the type of carbon source and availability of oxygen. The effect of illumination on pigment expression varied significantly between strains. In contrast to Chromatocurvus halotolerans, pigment production in Luminiphilus syltensis and Pseudohaliea rubra was repressed by light of moderate intensities, probably indicating a higher sensitivity to light-induced oxidative stress. The efficiency of using light for mixotrophic growth did not correlate with the cellular level of photosynthetic pigments, but depended mainly on the type of metabolized substrate with malate being the optimal carbon source in most cases. Conclusions Oligotrophic growth conditions or carbon limitation were not required for light-dependent mixotrophic growth in members of the OM60/NOR5 clade. The ability of using light as energy source and the fine tuning of photosynthesis gene expression depended mainly on the type of carbon source and oxygen availability, which indicates that the regulation of pigment production is controlled by the cellular

  12. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Oxygen cleaning. 197.452 Section 197.452 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS....452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or...

  13. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Oxygen cleaning. 197.452 Section 197.452 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS....452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or...

  14. 46 CFR 197.452 - Oxygen cleaning.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Oxygen cleaning. 197.452 Section 197.452 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS....452 Oxygen cleaning. The diving supervisor shall ensure that equipment used with oxygen or...

  15. Marine pollution

    SciTech Connect

    Albaiges, J. )

    1989-01-01

    This book covers the following topics: Transport of marine pollutants; Transformation of pollutants in the marine environment; Biological effects of marine pollutants; Sources and transport of oil pollutants in the Persian Gulf; Trace metals and hydrocarbons in Syrian coastal waters; and Techniques for analysis of trace pollutants.

  16. Marine04 Marine radiocarbon age calibration, 26 ? 0 ka BP

    SciTech Connect

    Hughen, K; Baille, M; Bard, E; Beck, J; Bertrand, C; Blackwell, P; Buck, C; Burr, G; Cutler, K; Damon, P; Edwards, R; Fairbanks, R; Friedrich, M; Guilderson, T; Kromer, B; McCormac, F; Manning, S; Bronk-Ramsey, C; Reimer, P; Reimer, R; Remmele, S; Southon, J; Stuiver, M; Talamo, S; Taylor, F; der Plicht, J v; Weyhenmeyer, C

    2004-11-01

    New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration datasets extend an additional 2000 years, from 0-26 ka cal BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically dated tree-ring samples, converted with a box-diffusion model to marine mixed-layer ages, cover the period from 0-10.5 ka cal BP. Beyond 10.5 ka cal BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific {sup 14}C reservoir age information to provide a single global marine mixed-layer calibration from 10.5-26.0 ka cal BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the radiocarbon age to calculate the underlying calibration curve. The marine datasets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring datasets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al.

  17. Blood Rheology in Marine Mammals

    PubMed Central

    Castellini, Michael A.; Baskurt, Oguz; Castellini, Judith M.; Meiselman, Herbert J.

    2010-01-01

    The field of blood oxygen transport and delivery to tissues has been studied by comparative physiologists for many decades. Within this general area, the particular differences in oxygen delivery between marine and terrestrial mammals has focused mainly on oxygen supply differences and delivery to the tissues under low blood flow diving conditions. Yet, the study of the inherent flow properties of the blood itself (hemorheology) is rarely discussed when addressing diving. However, hemorheology is important to the study of marine mammals because of the critical nature of the oxygen stores that are carried in the blood during diving periods. This review focuses on the essential elements of hemorheology, how they are defined and on fundamental rheological applications to marine mammals. While the comparative rationale used throughout the review is much broader than the particular problems associated with diving, the basic concepts focus on how changes in the flow properties of whole blood would be critical to oxygen delivery during diving. This review introduces the reader to most of the major rheological concepts that are relevant to the unique and unusual aspects of the diving physiology of marine mammals. PMID:21423386

  18. Bioprospecting marine plankton.

    PubMed

    Abida, Heni; Ruchaud, Sandrine; Rios, Laurent; Humeau, Anne; Probert, Ian; De Vargas, Colomban; Bach, Stéphane; Bowler, Chris

    2013-11-01

    The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics. PMID:24240981

  19. Bioprospecting Marine Plankton

    PubMed Central

    Abida, Heni; Ruchaud, Sandrine; Rios, Laurent; Humeau, Anne; Probert, Ian; De Vargas, Colomban; Bach, Stéphane; Bowler, Chris

    2013-01-01

    The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living within provide 50% of the oxygen we breathe, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis and major changes in our society, it is essential to turn our attention towards the sea to find additional solutions for a sustainable future. Remarkably, while we are overexploiting many marine resources, particularly the fisheries, the planktonic compartment composed of zooplankton, phytoplankton, bacteria and viruses, represents 95% of marine biomass and yet the extent of its diversity remains largely unknown and underexploited. Consequently, the potential of plankton as a bioresource for humanity is largely untapped. Due to their diverse evolutionary backgrounds, planktonic organisms offer immense opportunities: new resources for medicine, cosmetics and food, renewable energy, and long-term solutions to mitigate climate change. Research programs aiming to exploit culture collections of marine micro-organisms as well as to prospect the huge resources of marine planktonic biodiversity in the oceans are now underway, and several bioactive extracts and purified compounds have already been identified. This review will survey and assess the current state-of-the-art and will propose methodologies to better exploit the potential of marine plankton for drug discovery and for dermocosmetics. PMID:24240981

  20. Marine biology

    SciTech Connect

    Thurman, H.V.; Webber, H.H.

    1984-01-01

    This book discusses both taxonomic and ecological topics on marine biology. Full coverage of marine organisms of all five kingdoms is provided, along with interesting and thorough discussion of all major marine habitats. Organization into six major parts allows flexibility. It also provides insight into important topics such as disposal of nuclear waste at sea, the idea that life began on the ocean floor, and how whales, krill, and people interact. A full-color photo chapter reviews questions, and exercises. The contents are: an overview marine biology: fundamental concepts/investigating life in the ocean; the physical ocean, the ocean floor, the nature of water, the nature and motion of ocean water; general ecology, conditions for life in the sea, biological productivity and energy transfer; marine organisms; monera, protista, mycota and metaphyta; the smaller marine animals, the large animals marine habitats, the intertidal zone/benthos of the continental shelf, the photic zone, the deep ocean, the ocean under stress, marine pollution, appendix a: the metric system and conversion factors/ appendix b: prefixes and suffixes/ appendix c: taxonomic classification of common marine organisms, and glossary, and index.

  1. 2-Methylhopanoids: Biomarkers for Cyanobacteria and for Oxygenic Photosynthesis

    NASA Technical Reports Server (NTRS)

    Summons, R. E.; Jahnke, L. L.; Hope, J. M.; Logan, G. A.

    1999-01-01

    This paper reports new biomarker and carbon isotopic data for cultured cyanobacteria, cyano-bacterially- dominated ecosystems and ancient sedi-ments and petroleum. We found that cyanobacteria are the predominant source of a distinctive membrane lipid biomarker, namely 2- methylbacteriohopanepolyol (2-Me-BHP). We then sought evidence for a geochemical record of the fossil hydrocarbon analogues of these compounds (2- methylhopanes) and found a trend toward their in-creased relative abundance in marine sediments going back through geological time to 2500 Ma. We conclude that cyanobacteria were the dominant form of phytoplankton and source of molecular oxygen in the Proterozoic ocean. Extending the geological record of cyanobacteria further to Archean times is now a matter of finding a suitably preserved rock record. Additional information is contained in the original extended abstract.

  2. Marine Biology

    ERIC Educational Resources Information Center

    Dewees, Christopher M.; Hooper, Jon K.

    1976-01-01

    A variety of informational material for a course in marine biology or oceanology at the secondary level is presented. Among the topics discussed are: food webs and pyramids, planktonic blooms, marine life, plankton nets, food chains, phytoplankton, zooplankton, larval plankton and filter feeders. (BT)

  3. Marine Biomedicine

    ERIC Educational Resources Information Center

    Bang, Frederik B.

    1977-01-01

    Describes early scientific research involving marine invertebrate pathologic processes that may have led to new insights into human disease. Discussed are inquiries of Metchnikoff, Loeb, and Cantacuzene (immunolgic responses in sea stars, horseshoe crabs, and marine worms, respectively). Describes current research stemming from these early…

  4. 46 CFR 197.326 - Oxygen safety.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Oxygen safety. 197.326 Section 197.326 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.326 Oxygen safety. (a) Equipment used...

  5. 46 CFR 197.326 - Oxygen safety.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Oxygen safety. 197.326 Section 197.326 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE OCCUPATIONAL SAFETY AND HEALTH STANDARDS GENERAL PROVISIONS Commercial Diving Operations Equipment § 197.326 Oxygen safety. (a) Equipment used...

  6. Oxygen analyzer

    DOEpatents

    Benner, William H.

    1986-01-01

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N.sub.2), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable oxygen obtained by decomposing the sample at 1135.degree. C., or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135.degree. C. as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N.sub.2, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  7. Oxygen Therapy

    MedlinePlus

    ... 85-95% pure oxygen. The concentrator runs on electricity or a battery. A concentrator for home usually ... systems deliver 100% oxygen, and do not require electricity. A small canister can be filled from the ...

  8. Oxygen variance and meridional oxygen supply in the Tropical North East Atlantic oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Hahn, J.; Brandt, P.; Greatbatch, R. J.; Krahmann, G.; Körtzinger, A.

    2014-12-01

    The distribution of the mean oceanic oxygen concentration results from a balance between ventilation and consumption. In the eastern tropical Pacific and Atlantic, this balance creates extended oxygen minimum zones (OMZ) at intermediate depth. Here, we analyze hydrographic and velocity data from shipboard and moored observations, which were taken along the 23°W meridian cutting through the Tropical North East Atlantic (TNEA) OMZ, to study the distribution and generation of oxygen variability. By applying the extended Osborn-Cox model, the respective role of mesoscale stirring and diapycnal mixing in producing enhanced oxygen variability, found at the southern and upper boundary of the OMZ, is quantified. From the well-ventilated equatorial region toward the OMZ core a northward eddy-driven oxygen flux is observed whose divergence corresponds to an oxygen supply of about 2.4 μmol kg-1 year-1 at the OMZ core depth. Above the OMZ core, mesoscale eddies act to redistribute low- and high-oxygen waters associated with westward and eastward currents, respectively. Here, absolute values of the local oxygen supply >10 μmol kg-1 year-1 are found, likely balanced by mean zonal advection. Combining our results with recent studies, a refined oxygen budget for the TNEA OMZ is derived. Eddy-driven meridional oxygen supply contributes more than 50 % of the supply required to balance the estimated oxygen consumption. The oxygen tendency in the OMZ, as given by the multidecadal oxygen decline, is maximum slightly above the OMZ core and represents a substantial imbalance of the oxygen budget reaching about 20 % of the magnitude of the eddy-driven oxygen supply.

  9. Oxygen analyzer

    DOEpatents

    Benner, W.H.

    1984-05-08

    An oxygen analyzer which identifies and classifies microgram quantities of oxygen in ambient particulate matter and for quantitating organic oxygen in solvent extracts of ambient particulate matter. A sample is pyrolyzed in oxygen-free nitrogen gas (N/sub 2/), and the resulting oxygen quantitatively converted to carbon monoxide (CO) by contact with hot granular carbon (C). Two analysis modes are made possible: (1) rapid determination of total pyrolyzable obtained by decomposing the sample at 1135/sup 0/C, or (2) temperature-programmed oxygen thermal analysis obtained by heating the sample from room temperature to 1135/sup 0/C as a function of time. The analyzer basically comprises a pyrolysis tube containing a bed of granular carbon under N/sub 2/, ovens used to heat the carbon and/or decompose the sample, and a non-dispersive infrared CO detector coupled to a mini-computer to quantitate oxygen in the decomposition products and control oven heating.

  10. When did oxygenic photosynthesis evolve?

    PubMed

    Buick, Roger

    2008-08-27

    The atmosphere has apparently been oxygenated since the 'Great Oxidation Event' ca 2.4 Ga ago, but when the photosynthetic oxygen production began is debatable. However, geological and geochemical evidence from older sedimentary rocks indicates that oxygenic photosynthesis evolved well before this oxygenation event. Fluid-inclusion oils in ca 2.45 Ga sandstones contain hydrocarbon biomarkers evidently sourced from similarly ancient kerogen, preserved without subsequent contamination, and derived from organisms producing and requiring molecular oxygen. Mo and Re abundances and sulphur isotope systematics of slightly older (2.5 Ga) kerogenous shales record a transient pulse of atmospheric oxygen. As early as ca 2.7 Ga, stromatolites and biomarkers from evaporative lake sediments deficient in exogenous reducing power strongly imply that oxygen-producing cyanobacteria had already evolved. Even at ca 3.2 Ga, thick and widespread kerogenous shales are consistent with aerobic photoautrophic marine plankton, and U-Pb data from ca 3.8 Ga metasediments suggest that this metabolism could have arisen by the start of the geological record. Hence, the hypothesis that oxygenic photosynthesis evolved well before the atmosphere became permanently oxygenated seems well supported. PMID:18468984

  11. Marine Ecomechanics

    NASA Astrophysics Data System (ADS)

    Denny, Mark W.; Gaylord, Brian

    2010-01-01

    The emerging field of marine ecomechanics provides an explicit physical framework for exploring interactions among marine organisms and between these organisms and their environments. It exhibits particular utility through its construction of predictive, mechanistic models, a number of which address responses to changing climatic conditions. Examples include predictions of (a) the change in relative abundance of corals as a function of colony morphology, ocean acidity, and storm intensity; (b) the rate of disturbance and patch formation in beds of mussels, a competitive dominant on many intertidal shores; (c) the dispersal and recruitment patterns of giant kelps, an important nearshore foundation species; (d) the effects of turbulence on external fertilization, a widespread method of reproduction in the sea; and (e) the long-term incidence of extreme ecological events. These diverse examples emphasize the breadth of marine ecomechanics. Indeed, its principles can be applied to any ecological system.

  12. Origin of marine planktonic cyanobacteria

    PubMed Central

    Sánchez-Baracaldo, Patricia

    2015-01-01

    Marine planktonic cyanobacteria contributed to the widespread oxygenation of the oceans towards the end of the Pre-Cambrian and their evolutionary origin represents a key transition in the geochemical evolution of the Earth surface. Little is known, however, about the evolutionary events that led to the appearance of marine planktonic cyanobacteria. I present here phylogenomic (135 proteins and two ribosomal RNAs), Bayesian relaxed molecular clock (18 proteins, SSU and LSU) and Bayesian stochastic character mapping analyses from 131 cyanobacteria genomes with the aim to unravel key evolutionary steps involved in the origin of marine planktonic cyanobacteria. While filamentous cell types evolved early on at around 2,600–2,300 Mya and likely dominated microbial mats in benthic environments for most of the Proterozoic (2,500–542 Mya), marine planktonic cyanobacteria evolved towards the end of the Proterozoic and early Phanerozoic. Crown groups of modern terrestrial and/or benthic coastal cyanobacteria appeared during the late Paleoproterozoic to early Mesoproterozoic. Decrease in cell diameter and loss of filamentous forms contributed to the evolution of unicellular planktonic lineages during the middle of the Mesoproterozoic (1,600–1,000 Mya) in freshwater environments. This study shows that marine planktonic cyanobacteria evolved from benthic marine and some diverged from freshwater ancestors during the Neoproterozoic (1,000–542 Mya). PMID:26621203

  13. Origin of marine planktonic cyanobacteria.

    PubMed

    Sánchez-Baracaldo, Patricia

    2015-01-01

    Marine planktonic cyanobacteria contributed to the widespread oxygenation of the oceans towards the end of the Pre-Cambrian and their evolutionary origin represents a key transition in the geochemical evolution of the Earth surface. Little is known, however, about the evolutionary events that led to the appearance of marine planktonic cyanobacteria. I present here phylogenomic (135 proteins and two ribosomal RNAs), Bayesian relaxed molecular clock (18 proteins, SSU and LSU) and Bayesian stochastic character mapping analyses from 131 cyanobacteria genomes with the aim to unravel key evolutionary steps involved in the origin of marine planktonic cyanobacteria. While filamentous cell types evolved early on at around 2,600-2,300 Mya and likely dominated microbial mats in benthic environments for most of the Proterozoic (2,500-542 Mya), marine planktonic cyanobacteria evolved towards the end of the Proterozoic and early Phanerozoic. Crown groups of modern terrestrial and/or benthic coastal cyanobacteria appeared during the late Paleoproterozoic to early Mesoproterozoic. Decrease in cell diameter and loss of filamentous forms contributed to the evolution of unicellular planktonic lineages during the middle of the Mesoproterozoic (1,600-1,000 Mya) in freshwater environments. This study shows that marine planktonic cyanobacteria evolved from benthic marine and some diverged from freshwater ancestors during the Neoproterozoic (1,000-542 Mya). PMID:26621203

  14. Quantifying the heterogeneity of hypoxic and anoxic areas in the Baltic Sea by a simplified coupled hydrodynamic-oxygen consumption model approach

    NASA Astrophysics Data System (ADS)

    Lehmann, Andreas; Hinrichsen, Hans-Harald; Getzlaff, Klaus; Myrberg, Kai

    2014-06-01

    The Baltic Sea deep waters suffer from extended areas of hypoxia and anoxia. Their intra- and inter-annual variability is mainly determined by saline inflows which transport oxygenated water to deeper layers. During the last decades, oxygen conditions in the Baltic Sea have generally worsened and thus, the extent of hypoxic as well as anoxic bottom water has increased considerably. Climate change may further increase hypoxia due to changes in the atmospheric forcing conditions resulting in less deep water renewal Baltic inflows, decreased oxygen solubility and increased respiration rates. Feedback from climate change can amplify effects from eutrophication. A decline in oxygen conditions has generally a negative impact on marine life in the Baltic Sea. Thus, a detailed description of the evolution of oxygenated, hypoxic and anoxic areas is particularly required when studying oxygen-related processes such as habitat utilization of spawning fish, survival rates of their eggs as well as settlement probability of juveniles. One of today's major challenges is still the modeling of deep water dissolved oxygen, especially for the Baltic Sea with its seasonal and quasi-permanent extended areas of oxygen deficiency. The detailed spatial and temporal evolution of the oxygen concentrations in the entire Baltic Sea have been simulated for the period 1970-2010 by utilizing a hydrodynamic Baltic Sea model coupled to a simple pelagic and benthic oxygen consumption model. Model results are in very good agreement with CTD/O2-profiles taken in different areas of the Baltic Sea. The model proved to be a useful tool to describe the detailed evolution of oxygenated, hypoxic and anoxic areas in the entire Baltic Sea. Model results are further applied to determine frequencies of the occurrence of areas of oxygen deficiency and cod reproduction volumes.

  15. Marine Mammals.

    ERIC Educational Resources Information Center

    Meith, Nikki

    Marine mammals have not only fascinated and inspired human beings for thousands of years, but they also support a big business by providing flesh for sea-borne factories, sustaining Arctic lifestyles and traditions, and attracting tourists to ocean aquaria. While they are being harpooned, bludgeoned, shot, netted, and trained to jump through…

  16. Marine Resources

    NASA Technical Reports Server (NTRS)

    Sherman, J. W., III

    1975-01-01

    The papers presented in the marine session may be broadly grouped into several classes: microwave region instruments compared to infrared and visible region sensors, satellite techniques compared to aircraft techniques, open ocean applications compared to coastal region applications, and basic research and understanding of ocean phenomena compared to research techniques that offer immediate applications.

  17. Marine Trades.

    ERIC Educational Resources Information Center

    Abbott, Alan

    This curriculum guide provides materials for a competency-based course in marine trades at the secondary level. The curriculum design uses the curriculum infused model for the teaching of basic skills as part of vocational education and demonstrates the relationship of vocationally related skills to communication, mathematics, and science…

  18. Appreciating Oxygen

    ERIC Educational Resources Information Center

    Weiss, Hilton M.

    2008-01-01

    Photosynthetic flora and microfauna utilize light from the sun to convert carbon dioxide and water into carbohydrates and oxygen. While these carbohydrates and their derivative hydrocarbons are generally considered to be fuels, it is the thermodynamically energetic oxygen molecule that traps, stores, and provides almost all of the energy that…

  19. Oxygen safety

    MedlinePlus

    ... Watch out for splattering grease. It can catch fire. Keep children with oxygen away from the stove top and oven. Cooking ... under the bed. Keep liquids that may catch fire away from your oxygen. This includes cleaning products that contain oil, grease, ...

  20. Influence of strong monsoon winds on the water quality around a marine cage-culture zone in a shallow and semi-enclosed bay in Taiwan.

    PubMed

    Huang, Yuan-Chao Angelo; Huang, Shou-Chung; Meng, Pei-Jie; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2012-04-01

    Influences of marine cage culture and monsoonal disturbances, northeasterly (NE) and southwesterly (SW) monsoons on the proximal marine environment were investigated across a gradient of sites in a semi-enclosed bay, Magong Bay (Penghu Islands, Taiwan). Elevated levels of ammonia produced by the cages were the main pollutant and distinguished the cage-culture and intermediary zones (1000 m away from the cages) from the reference zone in the NE monsoon, indicating currents produced by the strong monsoon may have extended the spread of nutrient-enriched waters without necessarily flushing such effluents outside Magong Bay. Moreover, the levels of chlorophyll-a, dissolved oxygen, and turbidity were distinguishable between two seasons, suggesting that resuspension caused by the NE monsoon winds may also influence the water quality across this bay. It indicated that the impacts of marine cage culture vary as a function of distance, and also in response to seasonal movements of water driven by local climatic occurrences. PMID:22306313

  1. Marine Education: Progress and Promise.

    ERIC Educational Resources Information Center

    Fortner, Rosanne; Wildman, Terry M.

    1980-01-01

    Examined are the scope and status of precollege marine education, including history of marine education, present interdisciplinary marine education, informal approaches to marine education, marine awareness studies, and some implications of marine education. (Author/DS)

  2. Oxygen therapy and intraocular oxygenation.

    PubMed Central

    Jampol, L M

    1987-01-01

    When delivered to the corneal surface of rabbits or monkeys, 100% oxygen can significantly increase the pO2 in the aqueous humor. Under hyperbaric conditions (two atmospheres), an observed rise in the aqueous pO2 in rabbits breathing room air can be increased further by exposing the rabbit cornea to 100% oxygen. The high oxygen levels under hyperbaric conditions are mediated by intravascular and transcorneal delivery of oxygen. The increase in the pO2 levels in the aqueous can prevent sickling of intracameral human erythrocytes containing sickle hemoglobin. Thus, oxygen therapy transcorneally or systemically could potentially be used to treat a sickle cell hyphema. The exposure of rabbit eyes to 100% oxygen at the corneal surface is followed by autoregulation (constriction) of the iris vasculature. We could demonstrate no constriction in the eyes of two normal human volunteers or of four patients with chronic stable rubeosis iridis. Preretinal vitreous pO2 levels can be significantly raised by exposing monkeys to hyperbaric 100% oxygen. This procedure may be of value in treating acute, reversible ischemic inner retinal diseases. Transcorneal or vascular delivery of oxygen to the eye under normobaric or hyperbaric conditions may be effective in treating ischemic diseases of the anterior segment, such as anterior segment necrosis or rubeosis iridis, or ischemic inner retinal diseases. Images FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 B FIGURE 5 C FIGURE 5 A FIGURE 6 PMID:3447339

  3. Marine Jet

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The marine turbine pump pictured is the Jacuzzi 12YJ, a jet propulsion system for pleasure or commercial boating. Its development was aided by a NASA computer program made available by the Computer Software Management and Information Center (COSMIC) at the University of Georgia. The manufacturer, Jacuzzi Brothers, Incorporated, Little Rock, Arkansas, used COSMIC'S Computer Program for Predicting Turbopump Inducer Loading, which enabled substantial savings in development time and money through reduction of repetitive testing.

  4. Mechanistic Insight into Trimethylamine N-Oxide Recognition by the Marine Bacterium Ruegeria pomeroyi DSS-3

    PubMed Central

    Li, Chun-Yang; Chen, Xiu-Lan; Shao, Xuan; Wei, Tian-Di; Wang, Peng; Xie, Bin-Bin; Qin, Qi-Long; Zhang, Xi-Ying; Su, Hai-Nan; Song, Xiao-Yan; Shi, Mei; Zhou, Bai-Cheng

    2015-01-01

    ABSTRACT Trimethylamine N-oxide (TMAO) is an important nitrogen source for marine bacteria. TMAO can also be metabolized by marine bacteria into volatile methylated amines, the precursors of the greenhouse gas nitrous oxide. However, it was not known how TMAO is recognized and imported by bacteria. Ruegeria pomeroyi DSS-3, a marine Roseobacter, has an ATP-binding cassette transporter, TmoXWV, specific for TMAO. TmoX is the substrate-binding protein of the TmoXWV transporter. In this study, the substrate specificity of TmoX of R. pomeroyi DSS-3 was characterized. We further determined the structure of the TmoX/TMAO complex and studied the TMAO-binding mechanism of TmoX by biochemical, structural, and mutational analyses. A Ca2+ ion chelated by an extended loop in TmoX was shown to be important for maintaining the stability of TmoX. Molecular dynamics simulations indicate that TmoX can alternate between “open” and “closed” states for binding TMAO. In the substrate-binding pocket, four tryptophan residues interact with the quaternary amine of TMAO by cation-π interactions, and Glu131 forms a hydrogen bond with the polar oxygen atom of TMAO. The π-π stacking interactions between the side chains of Phe and Trp are also essential for TMAO binding. Sequence analysis suggests that the TMAO-binding mechanism of TmoX may have universal significance in marine bacteria, especially in the marine Roseobacter clade. This study sheds light on how marine microorganisms utilize TMAO. IMPORTANCE Trimethylamine N-oxide (TMAO) is an important nitrogen source for marine bacteria. The products of TMAO metabolized by bacteria are part of the precursors of the greenhouse gas nitrous oxide. It is unclear how TMAO is recognized and imported by bacteria. TmoX is the substrate-binding protein of a TMAO-specific transporter. Here, the substrate specificity of TmoX of Ruegeria pomeroyi DSS-3 was characterized. The TMAO-binding mechanism of TmoX was studied by biochemical, structural

  5. Research on rechargeable oxygen electrodes

    NASA Technical Reports Server (NTRS)

    Giner, J.; Malachesky, P. A.; Holleck, G.

    1971-01-01

    Studies were carried out on a number of factors which may influence the behavior of the platinum electrocatalyst of oxygen electrodes for use in rechargeable metal-oxygen batteries or hydrogen-oxygen fuel cells. The effects of pretreatments for various potentials and added ionic species, which could be present in such systems, were studied with reguard to: (1) the state of surface oxidation, (2) platinum dissolution, (3) the kinetics of oxygen evolution and reduction (including the role of hydrogen peroxide), and (4) changes in porous electrode structure. These studies were carried out on smooth platinum, platinized platinum, and Teflon-bonded platinum black electrodes in carefully purified electrolyte solutions. The main factors which appear to affect rechargeable oxygen electrode performance and life are: (1) the buildup of a refractory anodic layer on extended cycling, and (2) the dissolution of platinum.

  6. Micro-trace fossils reveal pervasive reworking of Pliocene sapropels by low-oxygen-adapted benthic meiofauna.

    PubMed

    Löhr, S C; Kennedy, M J

    2015-01-01

    Animal burrowers leave an indelible signature on the sedimentary record in most marine environments, with the seeming exception of low-oxygen environments. In modern sedimentary settings, however, sub-millimetre-sized benthic animals (meiofauna) are adapted to low oxygen and even sulfidic conditions. Almost nothing is known about their impact on ancient marine sediments because they leave few recognizable traces. Here we show, in classic Pliocene-aged anoxic facies from the Mediterranean, the first reported trace fossil evidence of meiofaunal activity and its relation to changing oxygenation. A novel approach utilizing electron imaging of ion-polished samples shows that meiofauna pervasively reworked sediment under oxygen-depleted conditions that excluded macrofauna, fragmenting organic laminae and emplacing 15- to 70-μm-diameter faecal pellets without macroscopically influencing the fabric. The extent of reworking raises the question: how pervasively altered are other sediments presently assumed to lack animal influence and how far into the geological record does this influence extend? PMID:25762504

  7. Smart Query Answering for Marine Sensor Data

    PubMed Central

    Shahriar, Md. Sumon; de Souza, Paulo; Timms, Greg

    2011-01-01

    We review existing query answering systems for sensor data. We then propose an extended query answering approach termed smart query, specifically for marine sensor data. The smart query answering system integrates pattern queries and continuous queries. The proposed smart query system considers both streaming data and historical data from marine sensor networks. The smart query also uses query relaxation technique and semantics from domain knowledge as a recommender system. The proposed smart query benefits in building data and information systems for marine sensor networks. PMID:22163772

  8. Marine Lubricants

    NASA Astrophysics Data System (ADS)

    Carter, B. H.; Green, D.

    Marine diesel engines are classified by speed, either large (medium speed) or very large (slow speed) with high efficiencies and burning low-quality fuel. Slow-speed engines, up to 200 rpm, are two-stroke with separate combustion chamber and sump connected by a crosshead, with trunk and system oil lubricants for each. Medium-speed diesels, 300-1500 rpm, are of conventional automotive design with one lubricant. Slow-speed engines use heavy fuel oil of much lower quality than conventional diesel with problems of deposit cleanliness, acidity production and oxidation. Lubricants are mainly SAE 30/40/50 monogrades using paraffinic basestocks. The main types of additives are detergents/dispersants, antioxidants, corrosion inhibitors, anti-wear/load-carrying/ep, pour-point depressants and anti-foam compounds. There are no simple systems for classifying marine lubricants, as for automotive, because of the wide range of engine design, ratings and service applications they serve. There are no standard tests; lubricant suppliers use their own tests or the Bolnes 3DNL, with final proof from field tests. Frequent lubricant analyses safeguard engines and require standard sampling procedures before determination of density, viscosity, flash point, insolubles, base number, water and wear metal content.

  9. Laboratory Experiences in Marine Biology for Upper Elementary and Secondary School Grades, Teachers Edition.

    ERIC Educational Resources Information Center

    Raimist, Roger J.

    Designed to assist the teacher who wishes to use marine organisms for biological laboratory investigations, this manual includes general information on maintaining marine aquaria and collecting marine organisms as well as five tested laboratory exercises. The exercises deal with the measurement of oxygen consumption (giving techniques for…

  10. Merchant Marine Ship Reactor

    DOEpatents

    Sankovich, M. F.; Mumm, J. F.; North, Jr, D. C.; Rock, H. R.; Gestson, D. K.

    1961-05-01

    A nuclear reactor for use in a merchant marine ship is described. The reactor is of pressurized, light water cooled and moderated design in which three passes of the water through the core in successive regions of low, intermediate, and high heat generation and downflow in a fuel region are made. The design makes a compact reactor construction with extended core life. The core has an egg-crate lattice containing the fuel elements that are confined between a lower flow baffle and upper grid plate, with the latter serving also as part of a turn- around manifold from which the entire coolant is distributed into the outer fuel elements for the second pass through the core. The inner fuel elements are cooled in the third pass. (AEC)

  11. MERCHANT MARINE SHIP REACTOR

    DOEpatents

    Mumm, J.F.; North, D.C. Jr.; Rock, H.R.; Geston, D.K.

    1961-05-01

    A nuclear reactor is described for use in a merchant marine ship. The reactor is of pressurized light water cooled and moderated design in which three passes of the water through the core in successive regions of low, intermediate, and high heat generation and downflow in a fuel region are made. The foregoing design makes a compact reactor construction with extended core life. The core has an egg-crate lattice containing the fuel elements confined between a lower flow baffle and upper grid plate, with the latter serving also as part of a turn- around manifold from which the entire coolant is distributed into the outer fuel elements for the second pass through the core. The inner fuel elements are cooled in the third pass.

  12. A Spinoff from Mariner

    NASA Technical Reports Server (NTRS)

    1989-01-01

    Among the technologies incorporated into the later Mariner missions was a dry film lubricant which offered exceptional lubrication quality for reduced friction and extended wear-life of mating parts in harsh interplanetary environments. Micro Surface Corporation acquired this technology, and currently market it as WS2 modified tungsten disulfide coating. A pressurized refrigerated air application process impinges a dry metallic WS2 coating without heat, curing, binders or adhesives. The coating binds instantly to metal or resin substrates with a 20 millionths of an inch thickness. Performance has been excellent in a variety of industries, particularly in plastics where in some operations, the coating increases production by reducing drag between tool steel and resin. Other advantages include product quality improvement, extension of equipment service life and maintenance elimination or reduction.

  13. Oxygen-Concentrating Cell

    NASA Technical Reports Server (NTRS)

    Buehler, K.

    1986-01-01

    High-purity oxygen produced from breathing air or from propellantgrade oxygen in oxygen-concentrating cell. Operating economics of concentrator attractive: Energy consumption about 4 Wh per liter of oxygen, slightly lower than conventional electrochemical oxygen extractors.

  14. Using oxygen at home

    MedlinePlus

    ... DO NOT use oil-based products, such as petroleum jelly (Vaseline). Ask your oxygen equipment provider about ... oxygen; Hypoxia - home oxygen; Hospice - home oxygen References American Thoracic Society. Why do I need oxygen therapy? ...

  15. Marine carotenoids and oxidative stress.

    PubMed

    Riccioni, Graziano

    2012-01-01

    Oxidative stress induced by reactive oxygen species plays an important role in the etiology of many diseases. Dietary phytochemical products, such as bioactive food components and marine carotenoids (asthaxantin, lutein, β-carotene, fucoxanthin), have shown an antioxidant effect in reducing oxidative markers stress. Scientific evidence supports the beneficial role of phytochemicals in the prevention of some chronic diseases. Many carotenoids with high antioxidant properties have shown a reduction in disease risk both in epidemiological studies and supplementation human trials. However, controlled clinical trials and dietary intervention studies using well-defined subjects population have not provided clear evidence of these substances in the prevention of diseases. The most important aspects of this special issue will cover the synthesis, biological activities, and clinical applications of marine carotenoids, with particular attention to recent evidence regarding anti-oxidant and anti-inflammatory properties in the prevention of cardiovascular disease. PMID:22363224

  16. Marine Carotenoids and Oxidative Stress

    PubMed Central

    Riccioni, Graziano

    2012-01-01

    Oxidative stress induced by reactive oxygen species plays an important role in the etiology of many diseases. Dietary phytochemical products, such as bioactive food components and marine carotenoids (asthaxantin, lutein, β-carotene, fucoxanthin), have shown an antioxidant effect in reducing oxidative markers stress. Scientific evidence supports the beneficial role of phytochemicals in the prevention of some chronic diseases. Many carotenoids with high antioxidant properties have shown a reduction in disease risk both in epidemiological studies and supplementation human trials. However, controlled clinical trials and dietary intervention studies using well-defined subjects population have not provided clear evidence of these substances in the prevention of diseases. The most important aspects of this special issue will cover the synthesis, biological activities, and clinical applications of marine carotenoids, with particular attention to recent evidence regarding anti-oxidant and anti-inflammatory properties in the prevention of cardiovascular disease. PMID:22363224

  17. Ecotoxicology of arsenic in the marine environment

    SciTech Connect

    Neff, J.M.

    1997-05-01

    Arsenic has a complex marine biogeochemistry that has important implications for its toxicity to marine organisms and their consumers. The average concentration of total arsenic in the ocean is about 1.7 {micro}g/L, about two orders of magnitude higher than the US Environmental Protection Agency`s human health criterion value of 0.0175 {micro}g/L. The dominant form of arsenic in oxygenated marine and brackish waters in arsenate (As V). The more toxic and potentially carcinogenic arsenite (As III) rarely accounts for more than 20% of total arsenic in seawater. Uncontaminated marine sediments contain from 5 to about 40 {micro}g/g dry weight total arsenic. Arsenate dominates in oxidized sediments and is associated primarily with iron oxyhydroxides. In reducing marine sediments, arsenate is reduced to arsenite and is associated primarily with sulfide minerals. Marine algae accumulate arsenate from seawater, reduce it to arsenite, and then oxidize the arsenite to a large number of organoarsenic compounds. The algae release arsenite, methylarsonic acid, and dimethylarsinic acid to seawater. Dissolved arsenite and arsenate are more toxic to marine phytoplankton than to marine invertebrates and fish. This may be due to the fact that marine animals have a limited ability to bioconcentrate inorganic arsenic from seawater but can bioaccumulate organoarsenic compounds from their food. Tissues of marine invertebrates and fish contain high concentrations of arsenic, usually in the range of about 1 to 100 {micro}g/g dry weight, most of it in the form of organoarsenic compounds, particularly arsenobetaine. Organoarsenic compounds are bioaccumulated by human consumers of seafood products, but the arsenic is excreted rapidly, mostly as organoarsenic compounds. Arsenobetaine, the most abundant organoarsenic compound in seafoods, is not toxic or carcinogenic to mammals. Little of the organoarsenic accumulated by humans from seafood is converted to toxic inorganic arsenite.

  18. Quantum extended supersymmetries

    NASA Astrophysics Data System (ADS)

    Grigore, D. R.; Scharf, G.

    2004-09-01

    We analyse some quantum multiplets associated with extended supersymmetries. We study in detail the general form of the causal (anti)commutation relations. The condition of positivity of the scalar product imposes severe restrictions on the (quantum) model. It is problematic if one can find out quantum extensions of the standard model with extended supersymmetries.

  19. Logo and Extended Definition.

    ERIC Educational Resources Information Center

    Desilets, Brendan J.

    1986-01-01

    Describes use of the programing language "Logo" and the Apple II computer to teach high school students how to write extended definitions. By defining procedures in Logo for drawing simple geometric patterns, students learn that good definition requires precision, rewriting and, in complex tasks, recursion, an aspect of extended definition…

  20. Extended or Restricted Childhood?

    ERIC Educational Resources Information Center

    Richards, Colin

    2005-01-01

    This article discusses the Government's proposals for "extended" primary schools, an important element in the recently-published five-year plan for education. The author expresses concern that extended primary schools will not provide a variety of experiences, including "play" experiences for young children.

  1. Extended conformal field theories

    NASA Astrophysics Data System (ADS)

    Taormina, Anne

    1990-08-01

    Some extended conformal field theories are briefly reviewed. They illustrate how non minimal models of the Virasoro algebra (c≥1) can become minimal with respect to a larger algebra. The accent is put on N-extended superconformal algebras, which are relevant in superstring compactification.

  2. Marine antivenoms.

    PubMed

    Currie, Bart J

    2003-01-01

    There is an enormous diversity and complexity of venoms and poisons in marine animals. Fatalities have occurred from envenoming by sea snakes, jellyfish, venomous fish such as stonefish, cone snails, and blue-ringed octopus. Deaths have also followed ingestion of toxins in shellfish, puffer fish (Fugu), and ciguatoxin-containing fish. However antivenoms are generally only available for envenoming by certain sea snakes, the major Australian box jellyfish (Chironex fleckeri) and stonefish. There have been difficulties in characterizing the toxins of C. fleckeri venom, and there are conflicting animals studies on the efficacy of C. fleckeri antivenom. The vast majority of C. fleckeri stings are not life-threatening, with painful skin welts the major finding. However fatalities that do occur usually do so within 5 to 20 minutes of the sting. This unprecedented rapid onset of cardiotoxicity in clinical envenoming suggests that antivenom may need to be given very early (within minutes) and possibly in large doses if a life is to be saved. Forty years of anecdotal experience supports the beneficial effect of stonefish antivenom in relieving the excruciating pain after stonefish spine penetration. It remains uncertain whether stonefish antivenom is efficacious in stings from spines of other venomous fish, and the recommendation of giving the antivenom intramuscularly needs reassessment. PMID:12807313

  3. 15 CFR Appendix B to Subpart G of... - Marine Reserve Boundaries

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 119.80000 °W B.5. Scorpion (Santa Cruz Island) Marine Reserve The Scorpion Marine Reserve (Scorpion... textual description. The Scorpion boundary extends from Point 1 to Point 2 along a straight line. It then... Point 5 along a straight line. Table B-5—Scorpion (Santa Cruz Island) Marine Reserve Point...

  4. 15 CFR Appendix B to Subpart G of... - Marine Reserve Boundaries

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 119.80000 °W B.5. Scorpion (Santa Cruz Island) Marine Reserve The Scorpion Marine Reserve (Scorpion... textual description. The Scorpion boundary extends from Point 1 to Point 2 along a straight line. It then... Point 5 along a straight line. Table B-5—Scorpion (Santa Cruz Island) Marine Reserve Point...

  5. 15 CFR Appendix B to Subpart G of... - Marine Reserve Boundaries

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 119.80000 °W B.5. Scorpion (Santa Cruz Island) Marine Reserve The Scorpion Marine Reserve (Scorpion... textual description. The Scorpion boundary extends from Point 1 to Point 2 along a straight line. It then... Point 5 along a straight line. Table B-5—Scorpion (Santa Cruz Island) Marine Reserve Point...

  6. Atmospheric Oxygen Photoabsorption

    NASA Technical Reports Server (NTRS)

    Slanger, Tom G.

    1996-01-01

    The work conducted on this grant was devoted to various aspects of the photophysics and photochemistry of the oxygen molecule. Predissociation linewidths were measured for several vibrational levels in the O2(B3 Sigma(sub u)(sup -)) state, providing good agreement with other groups working on this important problem. Extensive measurements were made on the loss kinetics of vibrationally excited oxygen, where levels between v = 5 and v = 22 were investigated. Cavity ring-down spectroscopy was used to measure oscillator strengths in the oxygen Herzberg bands. The great sensitivity of this technique made it possible to extend the known absorption bands to the dissociation limit as well as providing many new absorption lines that seem to be associated with new O2 transitions. The literature concerning the Herzberg band strengths was evaluated in light of our new measurements, and we made recommendations for the appropriate Herzberg continuum cross sections to be used in stratospheric chemistry. The transition probabilities for all three Herzberg band systems were re-evaluated, and we are recommending a new set of values.

  7. Hot Oxygen in the Upper Atmosphere of Mars and Venus

    NASA Astrophysics Data System (ADS)

    Paxton, L. J.

    1999-09-01

    There are a variety of physical processes which are capable of producing atoms or molecules with a non-thermal energy distribution. While these `hot' atoms or molecules may possess a relatively small amount of excess energy that difference can be important. Non-thermal atoms are important as the source of extended planetary coronae and as a mean of altering the photochemistry of atmospheric trace constituents. The observational consequences of these processes are varied. Some processes can actually lead to escape producing observable consequences for light atom isotopic ratios. The most notable example of this is the depletion of 14N relative to 15N from the dissociative recombination of 28N_2^+ and 29N_2^+ in the Mars upper atmosphere (e.g. Fox and Hac, 1997). Others processes lead to the production of an extended corona which can be observed using remote sensing or in situ measurement techniques. For example, an extended dual scale height hydrogen corona was detected around Venus from Mariner 5 (Barth et al., 1967). In this paper we review the photochemical sources for hot O in the exospheres of Mars and Venus and compare the predictions of a Monte Carlo simulation to data. We will focus on the observational evidence in ultraviolet measurements: Pioneer Venus Orbiter Ultraviolet Spectrometer (Venus) and Mariner 9 Ultraviolet Spectrograph (Mars). We report here a positive detection of a signal in the atomic oxygen resonance line at 130.4 nm in the Mariner 9 data and an extension of the work done by Paxton and Anderson (1992) for Venus. Barth, C.A., et al., Science, 158, 1675, 1967. Fox, J.L., and A. Hac, J. geophys. Res., 102, 9191, 1997. Jakosky, B.M., et al., Icarus, 111, 271, 1994. Luhmann, J.G., and J.U. Kozyra, J. geophys. Res., 96, 5457, 1991. Paxton, L.J., and D.E. Anderson, Ultraviolet Remote Sensing of Venus and Mars, Venus and Mars: Atmospheres, Ionospheres, and Solar Wind Interactions, Geophysical Monograph 66, eds. J.G. Luhmann, M. Tatrallyay, and R

  8. Hypoxia in the changing marine environment

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Cowie, G.; Naqvi, S. W. A.

    2013-03-01

    The predicted future of the global marine environment, as a combined result of forcing due to climate change (e.g. warming and acidification) and other anthropogenic perturbation (e.g. eutrophication), presents a challenge to the sustainability of ecosystems from tropics to high latitudes. Among the various associated phenomena of ecosystem deterioration, hypoxia can cause serious problems in coastal areas as well as oxygen minimum zones in the open ocean (Diaz and Rosenberg 2008 Science 321 926-9, Stramma et al 2008 Science 320 655-8). The negative impacts of hypoxia include changes in populations of marine organisms, such as large-scale mortality and behavioral responses, as well as variations of species distributions, biodiversity, physiological stress, and other sub-lethal effects (e.g. growth and reproduction). Social and economic activities that are related to services provided by the marine ecosystems, such as tourism and fisheries, can be negatively affected by the aesthetic outcomes as well as perceived or real impacts on seafood quality (STAP 2011 (Washington, DC: Global Environment Facility) p 88). Moreover, low oxygen concentration in marine waters can have considerable feedbacks to other compartments of the Earth system, like the emission of greenhouse gases to the atmosphere, and can affect the global biogeochemical cycles of nutrients and trace elements. It is of critical importance to prediction and adaptation strategies that the key processes of hypoxia in marine environments be precisely determined and understood (cf Zhang et al 2010 Biogeosciences 7 1-24).

  9. Operation of the computer model for microenvironment atomic oxygen exposure

    NASA Technical Reports Server (NTRS)

    Bourassa, R. J.; Gillis, J. R.; Gruenbaum, P. E.

    1995-01-01

    A computer model for microenvironment atomic oxygen exposure has been developed to extend atomic oxygen modeling capability to include shadowing and reflections. The model uses average exposure conditions established by the direct exposure model and extends the application of these conditions to treat surfaces of arbitrary shape and orientation.

  10. Extending The Shelf Life Of Blood Platelets

    NASA Technical Reports Server (NTRS)

    Surgenor, Douglas M.

    1988-01-01

    New method of storing human blood platelets extends vitality for transfusions. Packaged as suspension in sterile liquid in plastic blood bags. Each bag placed between pair of plastic grids, and rubberbands placed around sandwich thus formed to hold together. Stored upright in open air or in container through which air pumped at rate of at least 45 L/min. Ensures that platelets receive ample oxygen and expiratory carbon dioxide form platelets removed before pH drops to harmful levels.

  11. Enhancing aspergiolide A production from a shear-sensitive and easy-foaming marine-derived filamentous fungus Aspergillus glaucus by oxygen carrier addition and impeller combination in a bioreactor.

    PubMed

    Cai, Menghao; Zhou, Xiangshan; Lu, Jian; Fan, Weimin; Niu, Chuanpeng; Zhou, Jiushun; Sun, Xueqian; Kang, Li; Zhang, Yuanxing

    2011-02-01

    Production enhancement of a novel antitumor compound aspergiolide A from shear-sensitive and easy-foaming marine-derived fungus Aspergillus glaucus HB1-19 in a 5-l stirred bioreactor was investigated. Two types of impellers, i.e., six-flat-blade disc turbine impeller (DT) and three-sector-blade pitched blade turbine impeller (PB) were used in this work. In cultures with fermentation medium, the combination of upper PB and lower DT led to the maximum dry biomass (13.8 g/l) and aspergiolide A production (19.3 mg/l). However, two PBs brought the highest aspergiolide A yield coefficient (1.9 mg/g dry biomass) despite it produced the lowest dry biomass (5.3 g/l). By contrast, two DTs and the upper DT and lower PB showed insignificant results. Feeding 0.35% (v/v) n-dodecane in cultures with upper PB and lower DT further improved aspergiolide A production by 31.0%, i.e., 25.3 mg/l, which is also 322% higher than that in the ordinary cultures with two DTs. PMID:21074418

  12. Building Extended Families

    ERIC Educational Resources Information Center

    McKain, Barbara; McKain, Michael

    1970-01-01

    Discusses need for dissolution of the couple" relationship with substitution of the extended family which would permit each member to maintain individuality and to function on own merit. Suggests group living as preferable alternative. (CJ)

  13. Monitoring oxygenation.

    PubMed

    Severinghaus, John W

    2011-06-01

    Cyanosis was used for a century after dentists began pulling teeth under 100% N(2)O in 1844 because brief (2 min) severe hypoxia is harmless. Deaths came with curare and potent anesthetic respiratory arrest. Leland Clark's invention of a polarographic blood oxygen tension electrode (1954) was introduced for transcutaneous PO2 monitoring to adjust PEEP and CPAP PO2 to prevent premature infant blindness from excess O2 (1972). Oximetry for warning military aviators was tried after WW II but not used for routine monitoring until Takuo Aoyagi (1973) discovered an equation to measure SaO2 by the ratio of ratios of red and IR light transmitted through tissue as it changed with arterial pulses. Pulse oximetry (1982) depended on simultaneous technology improvements of light emitting red and IR diodes, tiny cheap solid state sensors and micro-chip computers. Continuous monitoring of airway anesthetic concentration and oxygen also became very common after 1980. Death from anesthesia fell 10 fold between 1985 and 2000 as pulse oximetry became universally used, but no proof of a causative relationship to pulse oximetry exists. It is now assumed that all anesthesiologist became much more aware of the dangers of prolonged hypoxia, perhaps by using the pulse oximeters. PMID:21717228

  14. Highly-precise measurements of ambient oxygen using near-infrared cavity-enhanced laser absorption spectrometry.

    PubMed

    Gupta, Manish

    2012-09-18

    Highly precise measurements of ambient oxygen have been used to constrain the carbon budget, study photosynthesis, estimate marine productivity, and prescribe individual pollution events to their point of origin. These studies require analyzers that can measure ambient oxygen with ppm-level precision. In this work, we utilize near-infrared off-axis integrated cavity output spectroscopy (off-axis ICOS) to quantify ambient oxygen with a precision (1σ, 100s) of ±7 ppm. By periodically calibrating the instrument, the analyzer is capable of making oxygen measurements to better than ±1 ppm (1σ). The sensor is highly linear (R(2) > 0.9999) over a wide dynamic range (0-100% oxygen). The sensor was combined with a commercial CO(2)/CH(4)/H(2)O Analyzer, and used to make measurements of respiration and fossil fuel pollution events with oxidative ratios ranging from 1.15-1.60. Future improvements will increase the analyzer precision (1σ, 100s) to better than ±1.4 ppm, and decrease the periodic referencing interval to >1 h. By including an additional diode laser, the instrument can be extended to make simultaneous measurements of O(2), CO(2), and H(2)O to enable improved understanding of carbon dioxide production and loss. PMID:22924385

  15. 50 CFR Figure 1 to Part 229 - Drift Gillnet Pinger Configuration and Extender Requirements

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 50 Wildlife and Fisheries 7 2010-10-01 2010-10-01 false Drift Gillnet Pinger Configuration and Extender Requirements 1 Figure 1 to Part 229 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS AUTHORIZATION...

  16. Australian developments in marine science

    NASA Astrophysics Data System (ADS)

    Coffin, Millard F.

    2012-07-01

    Australia is an island nation with about two thirds of its jurisdiction underwater. On 25 May 2012, Australia instituted the Seas and Submerged Lands (Limits of Continental Shelf) Proclamation 2012, confirming areas of seabed where Australia has exclusive rights to explore and exploit marine resources. This proclamation follows recommendations by the Commission on the Limits of the Continental Shelf, a body established under the United Nations Convention on the Law of the Sea, confirming Australia's entitlement to extended continental shelf, i.e., that beyond 200 nautical miles from the coastline, of some 2.56 million square kilometers, excluding Australian Antarctic Territory [Symonds et al., 2009] (Figure 1a).

  17. EVALUATING AN INNOVATIVE OXYGEN SENSOR FOR REMOTE SUBSURFACE OXYGEN MEASUREMENTS

    SciTech Connect

    Millings, M; Brian Riha, B; Warren Hyde, W; Karen Vangelas, K; Brian02 Looney, B

    2006-10-12

    Oxygen is a primary indicator of whether anaerobic reductive dechlorination and similar redox based processes contribute to natural attenuation remedies at chlorinated solvent contaminated sites. Thus, oxygen is a viable indicator parameter for documenting that a system is being sustained in an anaerobic condition. A team of researchers investigated the adaptation of an optical sensor that was developed for oceanographic applications. The optical sensor, because of its design and operating principle, has potential for extended deployment and sensitivity at the low oxygen levels relevant to natural attenuation. The results of the research indicate this tool will be useful for in situ long-term monitoring applications, but that the traditional characterization tools continue to be appropriate for characterization activities.

  18. Supermarket Marine Biology.

    ERIC Educational Resources Information Center

    Colby, Jennifer A.; And Others

    1995-01-01

    Describes a survey used to determine the availability of intact marine vertebrates and live invertebrates in supermarkets. Results shows that local supermarkets frequently provide a variety of intact marine organisms suitable for demonstrations, experiments, or dissections. (ZWH)

  19. Frontiers of marine science

    PubMed Central

    Webb, Thomas J.; Poloczanska, Elvira S.

    2011-01-01

    On 9–13 October 2010 early career scientists from the UK and Australia across marine research fields were given the opportunity to come together in Perth, Australia to discuss the frontiers of marine research and exchange ideas. PMID:21208943

  20. Extended lifetime railgap switch

    SciTech Connect

    Cohn, D.B.; Mendoza, P.J.

    1988-02-02

    In a railgap switch of the type having an elongate blade electrode made of conductive material, an elongate housing made of insulating material for supporting the blade electrode and plate electrode in opposed relation extending in the same direction with the blade centered over the plate and separated therefrom by a gap, and a gas filling the housing and the gap, the gas being selected to breakdown and switch from a highly insulative state to a highly conductive state upon application of a high voltage across the blade and plate electrodes, the improvement is described comprising: forming the blade with laterally extending transverse wing portions at the edge of the blade and adjacent the gap so as to extend in spaced parallel relation to the surface of the plate, the blade generally following the contour thereof to form an inverted T-shape structure with the wing portions extending transversely of the elongate dimension of the blade. The wing portions terminating in a pair of spaced parallel edges extending along the elongate direction of the blade to thereby create two spaced elongate edges along which arcs form serving to divide the erosion effects of discharge between them, the current through each edge being one-half of that in single-edge devices with ablation wear reduced accordingly to give significantly larger switch lifetime. The blade and wing portions limiting ablation erosion of the edges in a direction generally align with the plate contour so that the edge-to-plate separation remains substantially constant.

  1. Extending quantum mechanics entails extending special relativity

    NASA Astrophysics Data System (ADS)

    Aravinda, S.; Srikanth, R.

    2016-05-01

    The complementarity between signaling and randomness in any communicated resource that can simulate singlet statistics is generalized by relaxing the assumption of free will in the choice of measurement settings. We show how to construct an ontological extension for quantum mechanics (QMs) through the oblivious embedding of a sound simulation protocol in a Newtonian spacetime. Minkowski or other intermediate spacetimes are ruled out as the locus of the embedding by virtue of hidden influence inequalities. The complementarity transferred from a simulation to the extension unifies a number of results about quantum non-locality, and implies that special relativity has a different significance for the ontological model and for the operational theory it reproduces. Only the latter, being experimentally accessible, is required to be Lorentz covariant. There may be certain Lorentz non-covariant elements at the ontological level, but they will be inaccessible at the operational level in a valid extension. Certain arguments against the extendability of QM, due to Conway and Kochen (2009) and Colbeck and Renner (2012), are attributed to their assumption that the spacetime at the ontological level has Minkowski causal structure.

  2. Dangerous marine life.

    PubMed

    Harrison, L J

    1992-09-01

    All physicians must be educated in treating injuries incurred when a diver comes into contact with any dangerous marine life. Stinging invertebrates are the most commonly encountered dangerous marine animals. Venomous vertebrate marine animals are less common than stinging invertebrates and easier to recognize. However, they may be much more deadly. Sharks pose the greatest danger to divers. However, bites from other marine animals can be painful, become infected and require extensive medical treatment. PMID:1358999

  3. Extendable pipe crawler

    DOEpatents

    Hapstack, Mark

    1991-01-01

    A pipe crawler having a front leg assembly and a back leg assembly connected together by two air cylinders, each leg assembly having four extendable legs and a pair of actuators for sliding the extendable legs radially outward to increase the range of the legs when the pipe crawler enters a section of a pipe having a larger diameter. The crawler crawls by "inchworm"-like motion, the front leg assembly and back leg assembly alternately engaging and disengaging the wall of the pipe to hold the pipe crawler as the air cylinders alternately advance the front leg assembly and bring up the rear leg assembly. The pair of actuators of each leg assembly are parallel, adjacent and opposing acting so that each slides two adjacent extendable legs radially outward.

  4. Extendable pipe crawler

    DOEpatents

    Hapstack, M.

    1991-05-28

    A pipe crawler is described having a front leg assembly and a back leg assembly connected together by two air cylinders, each leg assembly having four extendable legs and a pair of actuators for sliding the extendable legs radially outward to increase the range of the legs when the pipe crawler enters a section of a pipe having a larger diameter. The crawler crawls by inchworm'-like motion, the front leg assembly and back leg assembly alternately engaging and disengaging the wall of the pipe to hold the pipe crawler as the air cylinders alternately advance the front leg assembly and bring up the rear leg assembly. The pair of actuators of each leg assembly are parallel, adjacent and opposing acting so that each slides two adjacent extendable legs radially outward. 5 figures.

  5. Marine vehicle ride quality

    NASA Technical Reports Server (NTRS)

    Gornstein, R. J.; Shultz, W. M.; Stair, L. D.

    1972-01-01

    The effects of marine vehicle design on passenger exposure to vibration and discomfort are discussed. The ride quality of advanced marine vehicles is examined. as a basis for marine vehicle selection in modern water transport systems. The physiological effects of rough water on passengers are identified as requiring investigation in order to determine the acceptable limits.

  6. Marine Education Knowledge Inventory.

    ERIC Educational Resources Information Center

    Hounshell, Paul B.; Hampton, Carolyn

    This 35-item, multiple-choice Marine Education Knowledge Inventory was developed for use in upper elementary/middle schools to measure a student's knowledge of marine science. Content of test items is drawn from oceanography, ecology, earth science, navigation, and the biological sciences (focusing on marine animals). Steps in the construction of…

  7. Marine Education Materials System.

    ERIC Educational Resources Information Center

    Gammisch, Sue; Gray, Kevin

    1980-01-01

    Described is a marine education materials clearinghouse, the Marine Education Materials System (MEMS). MEMS classifies marine education documents and reproduces them on microfiche for distribution. There are 25 distribution centers, each of which has a collection of documents and provides assistance on a request basis to teachers. (Author/DS)

  8. The Cassini Extended Mission

    NASA Astrophysics Data System (ADS)

    Seal, David A.; Buffington, Brent B.

    Based on the overwhelming success of the Cassini/Huygens 4-year tour of Saturn from July 2004 to June 2008, NASA Headquarters approved at least two years of extended mission for continued study of the target-rich Saturnian system. After a rigorous phase of science objective definition and trajectory design and analysis, the Cassini project initiated an efficient, scientifically intense and operationally challenging mission phase, including 60 orbits around Saturn, 26 close Titan flybys, and 10 close icy satellite flybys — including seven more flybys of Enceladus. At the conclusion of the 2-year extended mission, substantial operating margins should be present with some fascinating options for further extensions

  9. Devils Hole, Nevada, δ18O record extended to the mid-Holocene

    USGS Publications Warehouse

    Winograd, Isaac J.; Landwehr, Jurate M.; Coplen, Tyler B.; Sharp, Warren D.; Riggs, Alan C.; Ludwig, Kenneth R.; Kolesar, Peter T.

    2006-01-01

    The mid-to-late Pleistocene Devils Hole δ18O record has been extended from 60,000 to 4500 yr ago. The new δ18O time series, in conjunction with the one previously published, is shown to be a proxy of Pacific Ocean sea surface temperature (SST) off the coast of California. During marine oxygen isotope stages (MIS) 2 and 6, the Devil Hole and SST time series exhibit a steady warming that began 5000 to > 10,000 yr prior to the last and penultimate deglaciations. Several possible proximate causes for this early warming are evaluated. The magnitude of the peak δ18O or SST during the last interglacial (LIG) is significantly greater (1 per mill and 2 to 3°C, respectively) than the peak value of these parameters for the Holocene; in contrast, benthic δ18O records of ice volume show only a few tenths per mill difference in the peak value for these interglacials. Statistical analysis provides an estimate of the large shared information (variation) between the Devils Hole and Eastern Pacific SST time series from ∼ 41 to ∼ 2°N and enforces the concept of a common forcing among all of these records. The extended Devils Hole record adds to evidence of the importance of uplands bordering the eastern Pacific as a source of archives for reconstructing Pacific climate variability.

  10. The Hoiamides, Structurally Intriguing Neurotoxic Lipopeptides from Papua New Guinea Marine Cyanobacteria

    PubMed Central

    Choi, Hyukjae; Pereira, Alban R.; Cao, Zhengyu; Shuman, Cynthia F.; Engene, Niclas; Byrum, Tara; Matainaho, Teatulohi; Murray, Thomas F.; Mangoni, Alfonso; Gerwick, William H.

    2011-01-01

    Two related peptide metabolites, one a cyclic depsipeptide, hoiamide B (2), and the other a linear lipopeptide, hoiamide C (3), were isolated from two different collections of marine cyanobacteria obtained in Papua New Guinea. Their structures were elucidated by combining various techniques in spectroscopy, chromatography and synthetic chemistry. Both metabolites belong to the unique hoiamide structural class, characterized by possessing an acetate extended and S-adenosyl methionine modified isoleucine unit, a central triheterocyclic system comprised of two α-methylated thiazolines and one thiazole, as well as a highly oxygenated and methylated C-15 polyketide unit. In neocortical neurons, the cyclic depsipeptide 2 stimulated sodium influx and suppressed spontaneous Ca2+ oscillations with EC50 values of 3.9 μM and 79.8 nM, respectively, while 3 had no significant effects in these assays. PMID:20687534

  11. Pheromones in marine algae: A technical approach

    NASA Astrophysics Data System (ADS)

    Gassmann, G.; Müller, D. G.; Fritz, P.

    1995-03-01

    It is now well known that many marine organisms use low-molecular volatile substances as signals, in order to coordinate activities between different individuals. The study of such pheromones requires the isolation and enrichment of the secretions from undisturbed living cells or organisms over extended periods of time. The Grob-Hersch extraction device, which we describe here, avoids adverse factors for the biological materials such as strong water currents, rising gas bubbles or chemical solvents. Furthermore, the formation of sea-water spray is greatly reduced. The application of this technique for the isolation of pheromones of marine algae and animals is described.

  12. An Extended Duopoly Game.

    ERIC Educational Resources Information Center

    Eckalbar, John C.

    2002-01-01

    Illustrates how principles and intermediate microeconomic students can gain an understanding for strategic price setting by playing a relatively large oligopoly game. Explains that the game extends to a continuous price space and outlines appropriate applications. Offers the Mathematica code to instructors so that the assumptions of the game can…

  13. Towards Extended Vantage Theory

    ERIC Educational Resources Information Center

    Glaz, Adam

    2010-01-01

    The applicability of Vantage Theory (VT), a model of (colour) categorization, to linguistic data largely depends on the modifications and adaptations of the model for the purpose. An attempt to do so proposed here, called Extended Vantage Theory (EVT), slightly reformulates the VT conception of vantage by capitalizing on some of the entailments of…

  14. Modelling extended chromospheres

    NASA Technical Reports Server (NTRS)

    Linsky, J. L.

    1986-01-01

    Attention is given to the concept that the warm, partially ionized plasma (presently called chromosphere) associated with such stars as Alpha Boo and Rho Per extends outwards at least several photospheric radii. Calculations are presented for the Mg II K line in light of two input model atmospheres. Specific predictions are deduced from the results obtained by each of the two models.

  15. Protection of Marine Mammals.

    PubMed

    Knoll, Michaela; Ciaccia, Ettore; Dekeling, René; Kvadsheim, Petter; Liddell, Kate; Gunnarsson, Stig-Lennart; Ludwig, Stefan; Nissen, Ivor; Lorenzen, Dirk; Kreimeyer, Roman; Pavan, Gianni; Meneghetti, Nello; Nordlund, Nina; Benders, Frank; van der Zwan, Timo; van Zon, Tim; Fraser, Leanne; Johansson, Torbjörn; Garmelius, Martin

    2016-01-01

    Within the European Defense Agency (EDA), the Protection of Marine Mammals (PoMM) project, a comprehensive common marine mammal database essential for risk mitigation tools, was established. The database, built on an extensive dataset collection with the focus on areas of operational interest for European navies, consists of annual and seasonal distribution and density maps, random and systematic sightings, an encyclopedia providing knowledge on the characteristics of 126 marine mammal species, data on marine mammal protection areas, and audio information including numerous examples of various vocalizations. Special investigations on marine mammal acoustics were carried out to improve the detection and classification capabilities. PMID:26611003

  16. Oxygen supplies during a mass casualty situation.

    PubMed

    Ritz, Ray H; Previtera, Joseph E

    2008-02-01

    Mass casualty and pandemic events pose a substantial challenge to the resources available in our current health care system. The ability to provide adequate oxygen therapy is one of the systems that could be out-stripped in certain conditions. Natural disasters can disrupt manufacturing or delivery, and pandemic events can increase consumption beyond the available supply. Patients may require manual resuscitation, basic oxygen therapy, or positive-pressure ventilation during these scenarios. Available sources of oxygen include bulk liquid oxygen systems, compressed gas cylinders, portable liquid oxygen (LOX) systems, and oxygen concentrators. The last two are available in a variety of configurations, which include personal and home systems that are suitable for individual patients, and larger systems that can provide oxygen to multiple patients or entire institutions. Bulk oxygen systems are robust and are probably sustainable during periods of high consumption, but are at risk if manufacturing or delivery is disrupted. Compressed gas cylinders offer support during temporary periods of need but are not a solution for extended periods of therapy. Personal oxygen concentrators and LOX systems are limited in their application during mass casualty scenarios. Large-capacity oxygen concentrators and LOX systems may effectively provide support to alternative care sites or larger institutions. They may also be appropriate selections for governmental emergency-response scenarios. Careful consideration of the strengths and limitations of each of these options can reduce the impact of a mass casualty event. PMID:18218152

  17. EUVE Outsourced Extended Mission

    NASA Astrophysics Data System (ADS)

    Malina, R. F.; Biroscak, D.; Herz, A.; Christian, D.; Kaier, K.; Kaplan, G. C.; Lilly, S.; Quinn, T.; Stroozas, B.; Tucker, T.

    1996-05-01

    NASA has accepted an unsolicited proposal by the Center for EUV Atrophysics (CEA) at the University of California at Berkeley to manage spacecraft operations for the Extreme Ultraviolet Explorer (EUVE) extended mission. The proposal can serve as a model for university, government, and industry collaborations to respond to NASA's stated strategic goal to outsource all routine operations of scientific satellites to academia and industry. CEA has taken a conservative, low-cost approach to outsourcing that continues observatory operations, maintains the science return, and preserves the EUVE science archive. The Outsourced Extended Mission reduces yearly EUVE program costs, which may allow for a further extension of the science mission. This poster discusses the outsourced EUVE mission, its operations concept, NASA institutional support, and the roles and responsibilities of the government, university, and industry.

  18. Propelling Extended Objects

    ERIC Educational Resources Information Center

    Humbert, Richard

    2010-01-01

    A force acting on just part of an extended object (either a solid or a volume of a liquid) can cause all of it to move. That motion is due to the transmission of the force through the object by its material. This paper discusses how the force is distributed to all of the object by a gradient of stress or pressure in it, which creates the local…

  19. Extended Policies case

    EIA Publications

    2016-01-01

    The Annual Energy Outlook 2016 (AEO2016) Extended Policies case includes selected policies that go beyond current laws and regulations. Existing tax credits that have scheduled reductions and sunset dates are assumed to remain unchanged through 2040. Other efficiency policies, including corporate average fuel economy standards, appliance standards, and building codes, are expanded beyond current provisions; and the U.S. Environmental Protection Agency (EPA) Clean Power Plan (CPP) regulations that reduce carbon dioxide emissions from electric power generation are tightened after 2030.

  20. Extended Monitoring during Endoscopy.

    PubMed

    Mahmud, Nadim; Berzin, Tyler M

    2016-07-01

    Gastrointestinal endoscopic sedation has improved procedural and patient outcomes but is associated with attendant risks of oversedation and hemodynamic compromise. Therefore, close monitoring during endoscopic procedures using sedation is critical. This monitoring begins with appropriate staff trained in visual assessment of patients and analysis of basic physiologic parameters. It also mandates an array of devices widely used in practice to evaluate hemodynamics, oxygenation, ventilation, and depth of sedation. The authors review the evidence behind monitoring practices and current society recommendations and discuss forthcoming technologies and techniques that are poised to improve noninvasive monitoring of patients under endoscopic sedation. PMID:27372773

  1. Design manual: Oxygen Thermal Test Article (OTTA)

    NASA Technical Reports Server (NTRS)

    Chronic, W. L.; Baese, C. L.; Conder, R. L.

    1974-01-01

    The characteristics of a cryogenic tank for storing liquid hydrogen, nitrogen, oxygen, methane, or helium for an extended period of time with minimum losses are discussed. A description of the tank and control module, assembly drawings and details of major subassemblies, specific requirements controlling development of the system, thermal concept considerations, thermal analysis methods, and a record of test results are provided. The oxygen thermal test article thermal protection system has proven that the insulation system for cryogenic vessels is effective.

  2. Living with Oxygen Therapy

    MedlinePlus

    ... page from the NHLBI on Twitter. Living With Oxygen Therapy Oxygen therapy helps many people function better and be ... chronic obstructive pulmonary disease) Although you may need oxygen therapy continuously or for long periods, it doesn' ...

  3. Hyperbaric oxygen therapy

    MedlinePlus

    Hyperbaric oxygen therapy uses a special pressure chamber to increase the amount of oxygen in the blood. ... outpatient centers. The air pressure inside a hyperbaric oxygen chamber is about two and a half times ...

  4. Marine bioactives and potential application in sports.

    PubMed

    Gammone, Maria Alessandra; Gemello, Eugenio; Riccioni, Graziano; D'Orazio, Nicolantonio

    2014-05-01

    An enriched diet with antioxidants, such as vitamin E, vitamin C, β-carotene and phenolic compounds, has always been suggested to improve oxidative stress, preventing related diseases. In this respect, marine natural product (MNP), such as COX inhibitors, marine steroids, molecules interfering with factors involved in the modulation of gene expression (such as NF-κB), macrolides, many antioxidant agents, thermogenic substances and even substances that could help the immune system and that result in the protection of cartilage, have been recently gaining attention. The marine world represents a reserve of bioactive ingredients, with considerable potential as functional food. Substances, such as chitin, chitosan, n-3 oils, carotenoids, vitamins, minerals and bioactive peptides, can provide several health benefits, such as the reduction of cardiovascular diseases, anti-inflammatory and anticarcinogenic activities. In addition, new marine bioactive substances with potential anti-inflammatory, antioxidant and thermogenic capacity may provide health benefits and performance improvement, especially in those who practice physical activity, because of their increased free radical and Reacting Oxygen Species (ROS) production during exercise, and, particularly, in athletes. The aim of this review is to examine the potential pharmacological properties and application of many marine bioactive substances in sports. PMID:24796298

  5. Marine Bioactives and Potential Application in Sports

    PubMed Central

    Gammone, Maria Alessandra; Gemello, Eugenio; Riccioni, Graziano; D’Orazio, Nicolantonio

    2014-01-01

    An enriched diet with antioxidants, such as vitamin E, vitamin C, β-carotene and phenolic compounds, has always been suggested to improve oxidative stress, preventing related diseases. In this respect, marine natural product (MNP), such as COX inhibitors, marine steroids, molecules interfering with factors involved in the modulation of gene expression (such as NF-κB), macrolides, many antioxidant agents, thermogenic substances and even substances that could help the immune system and that result in the protection of cartilage, have been recently gaining attention. The marine world represents a reserve of bioactive ingredients, with considerable potential as functional food. Substances, such as chitin, chitosan, n-3 oils, carotenoids, vitamins, minerals and bioactive peptides, can provide several health benefits, such as the reduction of cardiovascular diseases, anti-inflammatory and anticarcinogenic activities. In addition, new marine bioactive substances with potential anti-inflammatory, antioxidant and thermogenic capacity may provide health benefits and performance improvement, especially in those who practice physical activity, because of their increased free radical and Reacting Oxygen Species (ROS) production during exercise, and, particularly, in athletes. The aim of this review is to examine the potential pharmacological properties and application of many marine bioactive substances in sports. PMID:24796298

  6. Icehouse-greenhouse variations in marine denitrification

    NASA Astrophysics Data System (ADS)

    Algeo, T. J.; Meyers, P. A.; Robinson, R. S.; Rowe, H.; Jiang, G. Q.

    2014-02-01

    Long-term secular variation in the isotopic composition of seawater fixed nitrogen (N) is poorly known. Here, we document variation in the N-isotopic composition of marine sediments (δ15Nsed) since 660 Ma (million years ago) in order to understand major changes in the marine N cycle through time and their relationship to first-order climate variation. During the Phanerozoic, greenhouse climate modes were characterized by low δ15Nsed (˜-2 to +2‰) and icehouse climate modes by high δ15Nsed (˜+4 to +8‰). Shifts toward higher δ15Nsed occurred rapidly during the early stages of icehouse modes, prior to the development of major continental glaciation, suggesting a potentially important role for the marine N cycle in long-term climate change. Reservoir box modeling of the marine N cycle demonstrates that secular variation in δ15Nsed was likely due to changes in the dominant locus of denitrification, with a shift in favor of sedimentary denitrification during greenhouse modes owing to higher eustatic (global sea-level) elevations and greater on-shelf burial of organic matter, and a shift in favor of water-column denitrification during icehouse modes owing to lower eustatic elevations, enhanced organic carbon sinking fluxes, and expanded oceanic oxygen-minimum zones. The results of this study provide new insights into operation of the marine N cycle, its relationship to the global carbon cycle, and its potential role in modulating climate change at multimillion-year timescales.

  7. High Selectivity Oxygen Delignification

    SciTech Connect

    Arthur J. Ragauskas Lucian A. Lucia Hasan Jameel

    2005-09-30

    The overall objective of this program was to develop improved extended oxygen delignification (EOD) technologies for current U.S. pulp mill operations. This was accomplished by: (1) Identifying pulping conditions that optimize O and OO performance; (2) Identifying structural features of lignin that enhance reactivity towards EOD of high kappa pulps; (3) Identifying factors minimizing carbohydrate degradation and improve pulp strength of EOD high kappa pulps; (4) Developing a simple, reproducible method of quantifying yield gains from EOD; and (5) Developing process conditions that significantly reduce the capital requirements of EOD while optimizing the yield benefits. Key research outcomes included, demonstrating the use of a mini-O sequence such as (E+O)Dkf:0.05(E+O) or Dkf:0.05(E+O)(E+O) without interstage washing could capture approximately 60% of the delignification efficiency of a conventional O-stage without the major capital requirements associated with an O-stage for conventional SW kraft pulps. The rate of formation and loss of fiber charge during an O-stage stage can be employed to maximize net fiber charge. Optimal fiber charge development and delignification are two independent parameters and do not parallel each other. It is possible to utilize an O-stage to enhance overall cellulosic fiber charge of low and high kappa SW kraft pulps which is beneficial for physical strength properties. The application of NIR and multi-variant analysis was developed into a rapid and simple method of determining the yield of pulp from an oxygen delignification stage that has real-world mill applications. A focus point of this program was the demonstration that Kraft pulping conditions and oxygen delignification of high and low-kappa SW and HW pulps are intimately related. Improved physical pulp properties and yield can be delivered by controlling the H-factor and active alkali charge. Low AA softwood kraft pulp with a kappa number 30 has an average improvement of 2% in

  8. Mariner 9 ultraviolet spectrometer experiment - Mars airglow spectroscopy and variations in Lyman alpha.

    NASA Technical Reports Server (NTRS)

    Barth, C. A.; Stewart, A. I.; Hord, C. W.; Lane, A. L.

    1972-01-01

    Mariner 9 ultraviolet spectrometer observations show the Mars airglow consists principally of emissions that arise from the interaction of solar ultraviolet radiation with carbon dioxide, the principal constituent of the Mars atmosphere. Two minor constituents, atomic hydrogen and atomic oxygen, also produce airglow emissions. The airglow measurements show that ionized carbon dioxide is only a minor constituent of the ionosphere. Using the airglow measurements of atomic oxygen, it is possible to infer that the major ion is ionized molecular oxygen. The escape rate of atomic hydrogen measured by Mariner 9 is approximately the same as that measured two years earlier by Mariner 6 and 7. If the current escape rate has been operating for 4.5 billion years and if water vapor is the ultimate source, an amount of oxygen has been generated that is far in excess of that observed at present. Mariner 9 observations of Mars Lyman alpha emission over a period of 120 days show variations of 20%.

  9. Methods for the detection of marine toxins

    SciTech Connect

    Wekell, M.M.; Manger, R.M.; Hadley, S.W.; Hungerford, J.M.

    1995-12-01

    Toxic materials have been dumped into the seas from waste streams and other pollutant sources such as runoff, etc. For protection of public health, it is essential that rapid, reliable and simple methods exist to detect marine toxins in seafoods. In addition, it is necessary to develop methods requiring a minimum of test material. Pure standards for many of the marine toxins are scarce. Reduced sample requirements extend the utility of detection methods in research and forensic applications as well. In the past, there was much reliance on the animal bioassay; however, this dependence hopefully will be reduced as newer instrumental techniques (chromatographic, mass spectrometric, electrophoretic), biochemical (immunochemical, receptor site assay), and cell bioassay methods are developed with a higher degree of precision and specificity. It is beneficial that a multiplicity of methods be available to detect marine toxins in seafoods. Each method has unique advantages and disadvantages.

  10. Marine biogeochemistry of mercury

    SciTech Connect

    Gill, G.A.

    1986-01-01

    Noncontaminating sample collection and handling procedures and accurate and sensitive analysis methods were developed to measure sub-picomolar Hg concentrations in seawater. Reliable and diagnostic oceanographic Hg distributions were obtained, permitting major processes governing the marine biogeochemistry of Hg to be identified. Mercury concentrations in the northwest Atlantic, central Pacific, southeast Pacific, and Tasman Sea ranged from 0.5 to 12 pM. Vertical Hg distributions often exhibited a maximum within or near the main thermocline. At similar depths, Hg concentrations in the northwest Atlantic Ocean were elevated compared to the N. Pacific Ocean. This pattern appears to result from a combination of enhanced supply of Hg to the northwest Atlantic by rainfall and scavenging removal along deep water circulation pathways. These observations are supported by geochemical steady-state box modelling which predicts a relatively short mean residence time for Hg in the oceans; demonstrating the reactive nature of Hg in seawater and precluding significant involvement in nutrient-type recyclic. Evidence for the rapid removal of Hg from seawater was obtained at two locations. Surface seawater Hg measurements along 160/sup 0/ W (20/sup 0/N to 20/sup 0/S) showed a depression in the equatorial upwelling area which correlated well with the transect region exhibiting low /sup 234/Th//sup 238/U activity ratios. This relationship implies that Hg will be scavenged and removed from surface seawater in biologically productive oceanic zones. Further, a broad minimum in the vertical distribution of Hg was observed to coincide with the intense oxygen minimum zone in the water column in coastal waters off Peru.

  11. Extended Testability Analysis Tool

    NASA Technical Reports Server (NTRS)

    Melcher, Kevin; Maul, William A.; Fulton, Christopher

    2012-01-01

    The Extended Testability Analysis (ETA) Tool is a software application that supports fault management (FM) by performing testability analyses on the fault propagation model of a given system. Fault management includes the prevention of faults through robust design margins and quality assurance methods, or the mitigation of system failures. Fault management requires an understanding of the system design and operation, potential failure mechanisms within the system, and the propagation of those potential failures through the system. The purpose of the ETA Tool software is to process the testability analysis results from a commercial software program called TEAMS Designer in order to provide a detailed set of diagnostic assessment reports. The ETA Tool is a command-line process with several user-selectable report output options. The ETA Tool also extends the COTS testability analysis and enables variation studies with sensor sensitivity impacts on system diagnostics and component isolation using a single testability output. The ETA Tool can also provide extended analyses from a single set of testability output files. The following analysis reports are available to the user: (1) the Detectability Report provides a breakdown of how each tested failure mode was detected, (2) the Test Utilization Report identifies all the failure modes that each test detects, (3) the Failure Mode Isolation Report demonstrates the system s ability to discriminate between failure modes, (4) the Component Isolation Report demonstrates the system s ability to discriminate between failure modes relative to the components containing the failure modes, (5) the Sensor Sensor Sensitivity Analysis Report shows the diagnostic impact due to loss of sensor information, and (6) the Effect Mapping Report identifies failure modes that result in specified system-level effects.

  12. Extended cooperative control synthesis

    NASA Technical Reports Server (NTRS)

    Davidson, John B.; Schmidt, David K.

    1994-01-01

    This paper reports on research for extending the Cooperative Control Synthesis methodology to include a more accurate modeling of the pilot's controller dynamics. Cooperative Control Synthesis (CCS) is a methodology that addresses the problem of how to design control laws for piloted, high-order, multivariate systems and/or non-conventional dynamic configurations in the absence of flying qualities specifications. This is accomplished by emphasizing the parallel structure inherent in any pilot-controlled, augmented vehicle. The original CCS methodology is extended to include the Modified Optimal Control Model (MOCM), which is based upon the optimal control model of the human operator developed by Kleinman, Baron, and Levison in 1970. This model provides a modeling of the pilot's compensation dynamics that is more accurate than the simplified pilot dynamic representation currently in the CCS methodology. Inclusion of the MOCM into the CCS also enables the modeling of pilot-observation perception thresholds and pilot-observation attention allocation affects. This Extended Cooperative Control Synthesis (ECCS) allows for the direct calculation of pilot and system open- and closed-loop transfer functions in pole/zero form and is readily implemented in current software capable of analysis and design for dynamic systems. Example results based upon synthesizing an augmentation control law for an acceleration command system in a compensatory tracking task using the ECCS are compared with a similar synthesis performed by using the original CCS methodology. The ECCS is shown to provide augmentation control laws that yield more favorable, predicted closed-loop flying qualities and tracking performance than those synthesized using the original CCS methodology.

  13. Extended duration lunar lander

    NASA Technical Reports Server (NTRS)

    Babic, Nikola; Carter, Matt; Cosper, Donna; Garza, David; Gonzalez, Eloy; Goodine, David; Hirst, Edward; Li, Ray; Lindsey, Martin; Ng, Tony

    1993-01-01

    Selenium Technologies has been conducting preliminary design work on a manned lunar lander for use in NASA's First Lunar Outpost (FLO) program. The resulting lander is designed to carry a crew of four astronauts to a prepositioned habitat on the lunar surface, remain on the lunar surface for up to 45 days while the crew is living in the habitat, then return the crew to earth via direct reentry and land recovery. Should the need arise, the crew can manually guide the lander to a safe lunar landing site, and live in the lander for up to ten days on the surface. Also, an abort to earth is available during any segment of the mission. The main propulsion system consists of a cluster of four modified Pratt and Whitney RL10 rocket engines that use liquid methane (LCH4) and liquid oxygen (LOX). Four engines are used to provide redundancy and a satisfactory engine out capability. Differences between the new propulsion system and the original system include slightly smaller engine size and lower thrust per engine, although specific impulse remains the same despite the smaller size. Concerns over nozzle ground clearance and engine reliability, as well as more information from Pratt and Whitney, brought about this change. The power system consists of a combination of regenerative fuel cells and solar arrays. While the lander is in flight to or from the moon, or during the lunar night, fuel cells provide all electrical power. During the lunar day, solar arrays are deployed to provide electrical power for the lander as well as electrolyzers, which separate some water back into hydrogen and oxygen for later use by the fuel cells. Total storage requirements for oxygen, hydrogen, and water are 61 kg, 551 kg, and 360 kg, respectively. The lander is a stage-and-a-half design with descent propellant, cargo, and landing gear contained in the descent stage, and the main propulsion system, ascent propellant, and crew module contained in the ascent stage. The primary structure for both

  14. Extended duration lunar lander

    NASA Astrophysics Data System (ADS)

    Babic, Nikola; Carter, Matt; Cosper, Donna; Garza, David; Gonzalez, Eloy; Goodine, David; Hirst, Edward; Li, Ray; Lindsey, Martin; Ng, Tony

    1993-05-01

    Selenium Technologies has been conducting preliminary design work on a manned lunar lander for use in NASA's First Lunar Outpost (FLO) program. The resulting lander is designed to carry a crew of four astronauts to a prepositioned habitat on the lunar surface, remain on the lunar surface for up to 45 days while the crew is living in the habitat, then return the crew to earth via direct reentry and land recovery. Should the need arise, the crew can manually guide the lander to a safe lunar landing site, and live in the lander for up to ten days on the surface. Also, an abort to earth is available during any segment of the mission. The main propulsion system consists of a cluster of four modified Pratt and Whitney RL10 rocket engines that use liquid methane (LCH4) and liquid oxygen (LOX). Four engines are used to provide redundancy and a satisfactory engine out capability. Differences between the new propulsion system and the original system include slightly smaller engine size and lower thrust per engine, although specific impulse remains the same despite the smaller size. Concerns over nozzle ground clearance and engine reliability, as well as more information from Pratt and Whitney, brought about this change. The power system consists of a combination of regenerative fuel cells and solar arrays. While the lander is in flight to or from the moon, or during the lunar night, fuel cells provide all electrical power. During the lunar day, solar arrays are deployed to provide electrical power for the lander as well as electrolyzers, which separate some water back into hydrogen and oxygen for later use by the fuel cells. Total storage requirements for oxygen, hydrogen, and water are 61 kg, 551 kg, and 360 kg, respectively. The lander is a stage-and-a-half design with descent propellant, cargo, and landing gear contained in the descent stage, and the main propulsion system, ascent propellant, and crew module contained in the ascent stage. The primary structure for both

  15. The Neoproterozoic oxygenation event: Environmental perturbations and biogeochemical cycling

    NASA Astrophysics Data System (ADS)

    Och, Lawrence M.; Shields-Zhou, Graham A.

    2012-01-01

    transition from dominantly pyrite burial to sulfate burial after the Neoproterozoic. Strong evidence for the oxygenation of the deep marine environment has emerged through elemental approaches over the past few years which were able to show significant increases in redox-sensitive trace-metal (notably Mo) enrichment in marine sediments not only during the GOE but even more pronounced during the inferred NOE. In addition to past studies involving Mo enrichment, which has been extended and further substantiated in the current review, we present new compilations of V and U concentrations in black shales throughout Earth history that confirm such a rise and further support the NOE. With regard to ocean ventilation, we also review other sedimentary redox indicators, such as iron speciation, molybdenum isotopes and the more ambiguous REE patterns. Although the timing and extent of the NOE remain the subjects of debate and speculation, we consider the record of redox-sensitive trace-metals and C and S contents in black shales to indicate delayed ocean ventilation later in the Cambrian on a global scale with regard to rising oxygen levels in the atmosphere which likely rose during the Late Neoproterozoic.

  16. The extended abdominoplasty.

    PubMed

    Shestak, Kenneth C

    2014-10-01

    This article illustrates the author's approach of directly excising adipose tissue excess in the lateral and posterior hip region by extending the lateral extent of the horizontal incision in a full abdominoplasty toward the posterior axillary line to produce a superior contour in this region. It is most applicable in patients with a significant adipose tissue excess in the lateral hip area that produces an outward convexity seen in the frontal, posterior, or oblique view. Such an excess represents a soft tissue "dog ear" composed of skin, and adipose tissue both deep and superficial to the superficial fascial system. PMID:25283456

  17. Extended Wordsearches in Chemistry

    NASA Astrophysics Data System (ADS)

    Cotton, Simon

    1998-04-01

    Students can be encouraged to develop their factual knowledge by use of puzzles. One strategy described here is the extended wordsearch, where the wordsearch element generates a number of words or phrases from which the answers to a series of questions are selected. The wordsearch can be generated with the aid of computer programs, though in order to make them suitable for students with dyslexia or other learning difficulties, a simpler form is more appropriate. These problems can be employed in a variety of contexts, for example, as topic tests and classroom end-of-lesson fillers. An example is provided in the area of calcium chemistry. Sources of suitable software are listed.

  18. Extended conformal algebras

    NASA Astrophysics Data System (ADS)

    Bouwknegt, Peter

    1988-06-01

    We investigate extensions of the Virasoro algebra by a single primary field of integer or halfinteger conformal dimension Δ. We argue that for vanishing structure constant CΔΔΔ, the extended conformal algebra can only be associative for a generic c-value if Δ=1/2, 1, 3/2, 2 or 3. For the other Δ<=5 we compute the finite set of allowed c-values and identify the rational solutions. The case CΔΔΔ≠0 is also briefly discussed. I would like to thank Kareljan Schoutens for discussions and Sander Bais for a careful reading of the manuscript.

  19. Spatially Extended Modelocking

    NASA Technical Reports Server (NTRS)

    Fork, Richard L.; Diffey, William M.; Gamble, Lisa; Keys, Andrew S.

    1999-01-01

    We examine the properties of optical fields that are extended in space over transverse dimensions of several meters or more in terms of both multiple spatial modes and also multiple temporal modes. We focus attention on the task of producing and maintaining well defined phase relationships for the set of spatial and temporal modes. In particular, we address operating regimes where the optical fields are not confined within an optical resonator, but still have well defined phase relations through the use of optical field sensing and correction techniques. Special applications of interest occur in safe beaming of optical power and in approaching optical intensities capable of producing nonlinear phenomena in the vacuum.

  20. Marine Indole Alkaloids.

    PubMed

    Netz, Natalie; Opatz, Till

    2015-08-01

    Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed. PMID:26287214

  1. Marine Indole Alkaloids

    PubMed Central

    Netz, Natalie; Opatz, Till

    2015-01-01

    Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed. PMID:26287214

  2. Optional Extended Year Program. FEEDBACK.

    ERIC Educational Resources Information Center

    Washington, Wanda

    The Optional Extended Year (OEY) program was initiated in Texas in 1995 and was first implemented in the Austin Independent School District (AISD) in 1996. The OEY is designed to add an extended school year and reduce student retention through four school-day options: (1) extended day; (2) extended week; (3) intersessions for year-round schools;…

  3. Integrating parasitology and marine ecology: Seven challenges towards greater synergy

    NASA Astrophysics Data System (ADS)

    Poulin, Robert; Blasco-Costa, Isabel; Randhawa, Haseeb S.

    2016-07-01

    Despite their very different historical origins as scientific disciplines, parasitology and marine ecology have already combined successfully to make important contributions to our understanding of the functioning of natural ecosystems. For example, robust assessments of the contribution of parasites to ecosystem biomass and energetics, and of their impact on community-wide biodiversity and food web structure, have all been made for the first time in marine systems. Nevertheless, for the marriage between parasitology and marine ecology to remain fruitful, several challenges must first be overcome. We discuss seven such challenges on the road to a greater synergy between these disciplines: (1) Raising awareness of parasitism as an ecological force by increasing the proportion of articles about parasites and diseases in marine ecology journals; (2) Making greater use of theory and conceptual frameworks from marine ecology to guide parasitological research; (3) Speeding up or at least maintaining the current rate at which marine parasites are found and described; (4) Elucidating a greater proportion of life cycles in all major groups of marine parasites; (5) Increasing the number of host-parasite model systems on which our knowledge is based; (6) Extending parasitological research offshore and into ocean depths; and (7) Developing, as needed, new epidemiological theory and transmission models for the marine environment. None of these challenges is insurmountable, and addressing just a few of them should guarantee that parasitology and marine ecology will continue to join forces and make further substantial contributions.

  4. Characterizing Marine Soundscapes.

    PubMed

    Erbe, Christine; McCauley, Robert; Gavrilov, Alexander

    2016-01-01

    The study of marine soundscapes is becoming widespread and the amount of data collected is increasing rapidly. Data owners (typically academia, industry, government, and defense) are negotiating data sharing and generating potential for data syntheses, comparative studies, analyses of trends, and large-scale and long-term acoustic ecology research. A problem is the lack of standards and commonly agreed protocols for the recording of marine soundscapes, data analysis, and reporting that make a synthesis and comparison of results difficult. We provide a brief overview of the components in a marine soundscape, the hard- and software tools for recording and analyzing marine soundscapes, and common reporting formats. PMID:26610968

  5. Artificial oxygen transport protein

    SciTech Connect

    Dutton, P. Leslie

    2014-09-30

    This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

  6. Lunar Prospector Extended Mission

    NASA Technical Reports Server (NTRS)

    Folta, David; Beckman, Mark; Lozier, David; Galal, Ken

    1999-01-01

    The National Aeronautics and Space Administration (NASA) selected Lunar Prospector as one of the discovery missions to conduct solar system exploration science investigations. The mission is NASA's first lunar voyage to investigate key science objectives since Apollo and was launched in January 1998. In keeping with discovery program requirements to reduce total mission cost and utilize new technology, Lunar Prospector's mission design and control focused on the use of innovative and proven trajectory analysis programs. As part of this effort, the Ames Research Center and the Goddard Space Flight Center have become partners in the Lunar Prospector trajectory team to provide the trajectory analysis, maneuver planning, orbit determination support, and product generation. At the end of 1998, Lunar Prospector completed its one-year primary mission at 100 km altitude above the lunar surface. On December 19, 1998, Lunar Prospector entered the extended mission phase. Initially the mission orbit was lowered from 100 km to a mean altitude of 40 km. The altitude of Lunar Prospector varied between 25 and 55 km above the mean lunar geode due to lunar potential effects. After one month, the lunar potential model was updated based upon the new tracking data at 40 km. On January 29, 1999, the altitude was lowered again to a mean altitude of 30 km. This altitude varies between 12 and 48 km above the mean lunar geode. Since the minimum altitude is very close to the mean geode, various approaches were employed to get accurate lunar surface elevation including Clementine altimetry and line of sight analysis. Based upon the best available terrain maps, Lunar Prospector will reach altitudes of 8 km above lunar mountains in the southern polar and far side regions. This extended mission phase of six months will enable LP to obtain science data up to 3 orders of magnitude better than at the mission orbit. This paper details the trajectory design and orbit determination planning, and

  7. Lunar Prospector Extended Mission

    NASA Technical Reports Server (NTRS)

    Folta, David; Beckman, Mark; Lozier, David; Galal, Ken

    1999-01-01

    The National Aeronautics and Space Administration (NASA) selected Lunar Prospector (LP) as one of the discovery missions to conduct solar system exploration science investigations. The mission is NASA's first lunar voyage to investigate key science objectives since Apollo and was launched in January 1998. In keeping with discovery program requirements to reduce total mission cost and utilize new technology, Lunar Prospector's mission design and control focused on the use of innovative and proven trajectory analysis programs. As part of this effort, the Ames Research Center and the Goddard Space Flight Center have become partners in the Lunar Prospector trajectory team to provide the trajectory analysis, maneuver planning, orbit determination support, and product generation. At the end of 1998, Lunar Prospector completed its one-year primary mission at 100 km altitude above the lunar surface. On December 19, 1998, Lunar Prospector entered the extended mission phase. Initially the mission orbit was lowered from 100 km to a mean altitude of 40 km. The altitude of Lunar Prospector varied between 25 and 55 km above the mean lunar geode due to lunar potential effects. After one month, the lunar potential model was updated based upon the new tracking data at 40 km. On January 29, 1999, the altitude was lowered again to a mean altitude of 30 km. This altitude varies between 12 and 48 km above the mean lunar geode. Since the minimum altitude is very close to the mean geode, various approaches were employed to get accurate lunar surface elevation including Clementine altimetry and line of sight analysis. Based upon the best available terrain maps, Lunar Prospector will reach altitudes of 8 km above lunar mountains in the southern polar and far side regions. This extended mission phase of six months will enable LP to obtain science data up to 3 orders of magnitude better than at the mission orbit. This paper details the trajectory design and orbit determination planning and

  8. Lunar Prospector Extended Mission

    NASA Astrophysics Data System (ADS)

    Folta, David; Beckman, Mark; Lozier, David; Galal, Ken

    1999-05-01

    The National Aeronautics and Space Administration (NASA) selected Lunar Prospector (LP) as one of the discovery missions to conduct solar system exploration science investigations. The mission is NASA's first lunar voyage to investigate key science objectives since Apollo and was launched in January 1998. In keeping with discovery program requirements to reduce total mission cost and utilize new technology, Lunar Prospector's mission design and control focused on the use of innovative and proven trajectory analysis programs. As part of this effort, the Ames Research Center and the Goddard Space Flight Center have become partners in the Lunar Prospector trajectory team to provide the trajectory analysis, maneuver planning, orbit determination support, and product generation. At the end of 1998, Lunar Prospector completed its one-year primary mission at 100 km altitude above the lunar surface. On December 19, 1998, Lunar Prospector entered the extended mission phase. Initially the mission orbit was lowered from 100 km to a mean altitude of 40 km. The altitude of Lunar Prospector varied between 25 and 55 km above the mean lunar geode due to lunar potential effects. After one month, the lunar potential model was updated based upon the new tracking data at 40 km. On January 29, 1999, the altitude was lowered again to a mean altitude of 30 km. This altitude varies between 12 and 48 km above the mean lunar geode. Since the minimum altitude is very close to the mean geode, various approaches were employed to get accurate lunar surface elevation including Clementine altimetry and line of sight analysis. Based upon the best available terrain maps, Lunar Prospector will reach altitudes of 8 km above lunar mountains in the southern polar and far side regions. This extended mission phase of six months will enable LP to obtain science data up to 3 orders of magnitude better than at the mission orbit. This paper details the trajectory design and orbit determination planning and

  9. Why marine islands are farther apart in the tropics.

    PubMed

    Brown, James H

    2014-06-01

    Species diversity of benthic marine organisms is highest in tropical archipelagoes. I hypothesize this is in large part a consequence of the temperature dependence of development times and dispersal distances of planktonic larvae. Metabolic theory predicts and empirical studies confirm that marine larvae develop faster and consequently have shorter durations in the plankton at higher temperatures. Metabolic theory can be extended to predict that species diversity of benthic marine organisms is highest in tropical archipelagoes, because warm temperatures limit dispersal and gene flow and isolated islands provide favorable conditions for speciation and coexistence. PMID:24823826

  10. Extended Ewald summation technique

    NASA Astrophysics Data System (ADS)

    Kylänpää, Ilkka; Räsänen, Esa

    2016-09-01

    We present a technique to improve the accuracy and to reduce the computational labor in the calculation of long-range interactions in systems with periodic boundary conditions. We extend the well-known Ewald method by using a linear combination of screening Gaussian charge distributions instead of only one. This enables us to find faster converging real-space and reciprocal space summations. The combined simplicity and efficiency of our method is demonstrated, and the scheme is readily applicable to large-scale periodic simulations, classical as well as quantum. Moreover, apart from the required a priori optimization the method is straightforward to include in most routines based on the Ewald method within, e.g., density-functional, molecular dynamics, and quantum Monte Carlo calculations.